Where Is the Power Supply Placed for Individually Mounted Channel Letters?

The cleanest channel-letter façades often require the most planning behind the wall. When letters are mounted individually, there is no visible raceway connecting them, so a natural question follows: where does the power supply go? In a modern LED system, the power supply affects far more than appearance. Its location influences wiring distance, voltage stability, heat dissipation, waterproofing, service access, installation time, and the number of wall penetrations.

For individually mounted channel letters, the power supply is usually installed remotely in a dry, ventilated, serviceable location behind the façade, above an accessible ceiling, inside a nearby electrical cabinet, or in a suitable outdoor enclosure. Low-voltage wires run from the power supply to each letter through planned wall penetrations. The final position depends on access, distance, environment, electrical load, and local requirements.

A sign can look perfectly simple in a rendering while hiding a difficult installation problem. Imagine opening the wall on installation day and discovering that the proposed power-supply position is blocked by concrete, plumbing, insulation, or a sealed architectural panel. The letters may already be finished, yet the original wiring plan is no longer workable. The best time to decide where the power supply belongs is therefore not when the installer arrives. It is when the wall, mounting method, electrical load, wire exits, and maintenance route are still being engineered.

Where Is the Power Supply Usually Placed?

For individually mounted channel letters, the power supply is normally installed away from the visible letter faces. Common positions include an accessible wall cavity, a service cupboard, a removable ceiling area, a nearby electrical cabinet, or a weather-protected outdoor enclosure. The right position must stay dry, release heat, remain accessible for replacement, and keep the low-voltage cable route reasonably short.

The exterior may show nothing except separate illuminated letters, but the hidden electrical arrangement still needs a clear home. Before production, the sign company and installer should confirm six points:

• Where the building’s AC power is available
• Where the power supply will be fixed
• Whether the location can be opened later
• How far the low-voltage cables must travel
• How each letter’s wire will pass through the wall
• Whether the power supply will be indoors or outdoors

Iduoduo’s installation standard requires the power-supply position to be dry, ventilated, serviceable, free from standing water, protected from continuous exposure, and not permanently sealed inside the building. It also calls for confirmation of the input voltage, number of power supplies, mounting position, controls, wire length, voltage drop, and final electrical connection before production.

Proposed position	When it works well	What commonly goes wrong	What to confirm
Behind an accessible wall	The letters are mounted directly to a storefront with rear access	The cavity is later covered by cabinetry or wall finishes	Access panel, wall depth, cable route and ventilation
Above a removable ceiling	The sign is close to a soffit or suspended ceiling	The supply is buried above fixed plasterboard or insulation	Ceiling access, heat, cable distance and service clearance
Electrical or utility cupboard	A clean, organized service point is available nearby	The cupboard is too far away, producing long low-voltage runs	Cable length, conductor size, circuit labeling and access
Inside a raceway	Rear wall access is limited	The raceway becomes larger or more visible than expected	Raceway size, removable cover, drainage and finish
Behind a backer panel	The wall is uneven or cable exits need to be grouped	The panel is sealed with no service opening	Panel depth, access cover, wiring route and fixing points
Outdoor electrical enclosure	No practical indoor location is available	Heat, rainwater, corrosion or poor cable entry causes failure	Enclosure protection, drainage, shade, ventilation and maintenance

Is It Installed Behind the Wall?

Behind the wall is the most common answer for a clean direct-mounted façade, but the phrase can be misleading. The power supply should not simply be pushed into an unknown cavity and sealed over. It needs a defined mounting surface, a reachable access route and enough room for wiring, terminal connections and replacement.

A suitable arrangement may place the power supply on the interior side of the storefront wall, inside a removable bulkhead, behind a service panel or within an accessible architectural cavity. Low-voltage leads from the letters pass through planned wall holes and connect to labeled branch wiring behind the façade.

The installer should inspect both sides of the wall before the production drawing is approved. A storefront photograph may show a flat aluminum panel outside, while the inside contains steel columns, insulation, pipes, shelving or a concrete beam. Such obstacles can make the proposed power-supply position unusable.

For example, a 12-letter storefront sign may be divided into two electrical groups. One power supply serves the first six letters and another serves the remaining six. Placing both units near the center of the wordmark may shorten the longest cable runs, but the arrangement only works when a service opening exists behind the center area.

A useful site check includes:

• Wall material and total wall depth
• Interior access behind the letter area
• Structural framing or metal studs
• Water pipes, sprinklers and HVAC ducts
• Existing mains power location
• Planned cabinets, displays or wall finishes
• Space needed to remove the power supply later

If the wall is solid concrete, stone or masonry with no usable rear cavity, forcing a behind-wall arrangement may increase drilling, conduit work and interior repairs. A raceway, backer panel or nearby service enclosure may produce a more practical installation.

Which Indoor Spaces Are Suitable?

Indoor placement usually gives the power supply better protection from rain, direct sunlight and severe temperature changes. Suitable positions can include a utility cupboard, electrical room, service corridor, accessible ceiling, removable bulkhead, cabinet or dedicated sign-service compartment.

The nearest available space is not always the best position. A cupboard directly behind the sign may contain cleaning chemicals, water pipes or equipment that generates heat. A stockroom may be accessible on installation day but later become blocked by fixed shelving. A restaurant ceiling may contain steam, grease or high temperatures even though it is technically indoors.

A suitable indoor position should provide:

• A solid surface for fastening the power supply
• Air space around the unit
• Access to input and output terminals
• Enough room to remove the unit without cutting the wall
• Protection from water leaks and condensation
• A clear path for mains and low-voltage cables
• Labels identifying which letters each unit serves

Service access matters because power supplies are replaceable electrical components. The letters may remain in good condition while one supply eventually needs inspection or replacement. A technician should not have to remove several finished wall panels just to reach a unit worth a small fraction of the complete sign.

The low-voltage distance also deserves attention. For early planning, the following ranges are useful, but they are not universal engineering or code limits:

One-way cable distance	Early planning approach
Up to about 3 m	Usually straightforward when the cable and load are correctly matched
About 3–10 m	Calculate voltage drop and review conductor size, branching and supply position
More than about 10 m	Consider moving the supply closer, splitting the load, increasing conductor size or using a suitable 24V system

Current is one reason distance becomes important. A 180 W lighting load draws approximately 15 A at 12V but only 7.5 A at 24V. The lower-current arrangement can reduce voltage-drop pressure, although LED compatibility, cable size, power-supply selection and local requirements still need engineering review.

Can It Be Placed Above a Ceiling?

Yes, an accessible ceiling is often a practical position for indoor channel letters, reception logos, shopping-center signs and letters mounted close to a soffit. The ceiling can conceal the equipment while keeping it relatively close to the sign.

The difference between an accessible ceiling and a closed ceiling is critical. A suspended ceiling with removable tiles normally provides a clear maintenance route. A plasterboard ceiling without an access hatch does not. Once painters and interior contractors finish the surface, a hidden supply may become impossible to replace without cutting and repairing the ceiling.

Before choosing the ceiling space, check:

• Whether a tile or access panel can be removed
• The horizontal and vertical distance to the letters
• Whether ducts or structural members block the route
• Whether insulation will cover the power supply
• Whether water pipes or roof drains run above it
• Whether the area becomes unusually hot
• Whether a technician can work safely at the access point

The power supply should not rest loosely on a ceiling tile. It should be fixed to an appropriate surface or installed in a properly planned enclosure. Wiring also needs support rather than hanging across sharp framing or lying on heat-producing equipment.

For a long reception logo, putting every supply at one end of the ceiling may appear convenient but can create unequal cable lengths. The letters closest to the unit may receive stable voltage while distant sections experience greater loss. Dividing the logo into two balanced zones often produces a cleaner wiring layout and easier fault finding.

Access panels should also be coordinated with the room design. Placing the hatch directly above permanent shelving, a reception counter or decorative feature can make maintenance difficult even though the ceiling is technically accessible.

Is an Outdoor Enclosure Suitable?

An outdoor enclosure can be used when no practical indoor space is available. Common applications include channel letters on canopies, roof structures, detached façades, exterior parapets and elevations with no rear access.

Outdoor placement needs a complete environmental plan. A waterproof-rated power supply does not mean it can be left on the ground, placed in standing water or exposed directly to every weather condition. The enclosure, cable entries, mounting direction, drainage and ventilation all affect reliability. The Iduoduo waterproofing standard specifically notes that outdoor power arrangements must consider the power supply’s own protection, installation box, orientation, ventilation, terminals, cable entries, drainage, sunlight and service access.

The enclosure should normally be:

• Mounted above locations where water can collect
• Positioned so cable entries do not funnel rain inside
• Protected from continuous direct sunlight where practical
• Made from material suitable for the local environment
• Large enough for wiring bends and heat release
• Reachable without removing the entire sign
• Fitted with a serviceable cover
• Installed in the correct orientation

A sealed box is not automatically a cool box. Direct afternoon sunlight can raise the enclosure temperature well above the surrounding air temperature. Packing several heavily loaded supplies into a small enclosure can further increase heat. A shaded position with suitable internal space may perform better than the most visually hidden location.

Cable entries often cause more problems than the enclosure body. Outdoor wiring may require compatible glands, bushings, seals, strain relief and downward cable routing. A drip loop can help water fall away before the cable enters the box. Upward-facing holes and poorly sealed penetrations are more likely to collect or guide water.

The wall opening still requires local waterproofing. Even when the letters and power supply are correctly protected, an unsealed cable hole can allow water into the building. Factory waterproofing and site waterproofing are separate responsibilities.

Is It Ever Installed Inside a Letter?

A power supply can be installed inside certain large letters or custom-built sign structures, but the arrangement is uncommon for ordinary individually mounted channel letters. Most letters already need internal space for LED modules, wiring, light distribution, fasteners and drainage. Adding a power supply may interfere with one or more of those functions.

Internal placement is more realistic when the letter is large and deep enough to provide:

• Adequate clearance around the unit
• A removable service face or back
• A suitable fixing position
• Safe separation from LED wiring
• Acceptable operating temperature
• Weather protection and drainage
• Access after the letter is installed

The smallest letter often determines whether an internal system is practical. A large initial letter may have plenty of room, while narrow lowercase letters do not. Using one different electrical structure for each letter can also make production, installation and maintenance unnecessarily complicated.

Internal power supplies add weight to the letters and can affect mounting hardware. A technician may need a lift to open a high-mounted letter, while a remote supply in an accessible cupboard could be replaced from indoors. For signs mounted 5–10 m above ground, service access can become a significant operating cost.

A central remote system is usually easier to label and test. Several letters can share one correctly sized supply, or the sign can be divided into clear zones. The factory can test each zone, mark the cables and pack the matched supplies separately. Iduoduo’s records may include power-supply models, quantities, wiring groups, wire exits and tested electrical configuration, helping the installer reproduce the factory arrangement on site.

Internal placement may still make sense for a large logo box, oversized symbol or specially engineered self-contained letter. The decision should come from an approved section drawing rather than an assumption made after manufacturing begins.

The final choice is rarely based on hiding the power supply as completely as possible. A good location keeps the exterior clean while allowing the electrical system to run correctly and remain repairable. A position that looks convenient on a rendering can become expensive when the cable run is too long, the ceiling cannot be opened, the enclosure overheats or the wall must be cut apart for service. Confirming the exact position before production protects the sign, the building finish and the installation schedule.

How Are the Letters Connected to Power?

Individually mounted channel letters usually contain low-voltage LED modules connected through separate branch wires. Each letter’s cable passes through the mounting surface and joins a remote 12V or 24V power system behind the wall, above the ceiling, or inside a serviceable enclosure. Larger signs are divided into labeled electrical groups to control load, cable length, voltage drop, maintenance, and fault impact.

The finished façade may show ten completely separate letters, yet the electrical system behind them is normally organized as one coordinated network:

1. Building AC power reaches one or more power supplies.
2. The power supplies convert the building voltage to 12V or 24V DC.
3. Low-voltage circuits run from the supplies toward the sign.
4. Each letter connects to a planned branch.
5. Every branch is identified by voltage, load, polarity, cable, power supply and circuit number.
6. A qualified local electrician completes the building-side connection and verifies the site installation.

Iduoduo configures electrical systems according to LED load, system voltage, cable length, voltage drop, control requirements, installation environment and destination market. Project records can include power-supply models, rated power, quantity, wire specifications, branch numbers, wiring diagrams and test results.

How Do Wires Pass Through the Wall?

Each individually mounted letter normally has one or more low-voltage leads exiting from its rear panel. The leads pass through preplanned holes in the façade and connect to branch wiring on the hidden side of the wall.

The wire exit is not a minor production detail. Its position affects drilling, letter alignment, waterproofing, cable visibility and installation time. A wire placed only 30–50 mm away from the usable wall cavity may still create a serious problem when the drilling point hits a steel stud, concrete beam, window frame or concealed pipe.

Before production, the drawing should identify:

• The wire exit position for every letter
• The distance from the exit to the letter edge
• The required cable length outside the letter
• The positive and negative conductors
• Any separate front-lit and halo-lit circuits
• The fixing holes or stud positions
• The corresponding location on the installation template
• The branch or power-supply number

A typical front-lit letter may need one two-core low-voltage cable. A front-and-halo-lit letter may need separate circuits when the two lighting effects must be switched or dimmed independently. RGB or RGBW systems require additional channel wires or compatible control cables.

The installer should not need to open every letter to identify the leads. Cable labels can follow a simple pattern:

Cable label	Meaning
L1-A	Letter 1, Circuit A
L2-A	Letter 2, Circuit A
L3-B	Letter 3, Circuit B
LOGO-C	Logo, Circuit C
F-LIGHT	Front illumination
H-LIGHT	Halo illumination

The same labels should appear on the wiring diagram, cables, power supplies and packing list. Clear identification becomes particularly valuable when a long company name contains repeated letters. Without labels, an installer may have several identical-looking cables entering the same ceiling space.

Most sign LED modules use parallel or branch-style low-voltage wiring so each lighting group receives the specified operating voltage. A long chain from one letter to the next is generally less desirable because the first connection may carry excessive current and the last letters may experience greater voltage loss. The Iduoduo electrical standard calls for control of polarity, wire color, branch layout, connector load and end-of-line voltage drop.

A practical hidden-wiring route may look like this:

Building AC circuit → disconnect or control device → power supply → low-voltage distribution point → labeled letter branches → individual letter leads

The power supply converts the building input into the voltage required by the LEDs. A letter marked “24V DC” must not be connected directly to a 120V or 230V building circuit. The 24V marking refers to the output side of the power supply, not the mains input.

Do All Letters Share One Power Supply?

Several letters can share one power supply, but the decision must come from the calculated LED load and cable layout. Letter count alone is not enough.

A compact five-letter sign may operate correctly from one supply. A twelve-letter storefront sign may need two, three or more supplies because of higher power, longer cable runs, separate lighting effects or limited space at the installation point.

One power supply offers a simple arrangement:

• Fewer components
• Fewer mains connections
• Lower equipment count
• One central service point
• Easier initial labeling

However, one large central supply may also create:

• Longer low-voltage cables
• Higher current on the main output
• Greater voltage-drop risk
• A larger affected area if the supply fails
• More wires entering one terminal area
• More difficult fault isolation

Multiple power supplies allow the sign to be divided into practical zones. A long wordmark could be separated into left and right groups. A logo and company name could use different supplies. Front lighting and halo lighting could also remain independent.

A simple zoning example:

Electrical group	Connected elements	Calculated LED load	Selected supply arrangement
Group A	Letters 1–5	150 W	One supply with suitable reserve
Group B	Letters 6–10	145 W	One supply with suitable reserve
Group C	Logo	72 W	Separate supply
Group D	Halo lighting	90 W	Separate controlled supply

The values above are illustrative. Actual loads must come from the approved LED layout and component specifications.

Multiple supplies are particularly useful when:

• The sign is several meters wide
• Letter groups are far apart
• Separate switching is required
• Front and halo lighting operate independently
• Different colors use different controls
• One section must remain illuminated if another supply fails
• Service access is available at more than one position
• Cable lengths would otherwise become excessive

More supplies do not automatically create a better system. Every additional unit needs mounting space, mains input, low-voltage terminals, labels, ventilation and service access. More connection points also mean more places to inspect during installation.

Outputs from separate power supplies should not be joined together casually. The Iduoduo electrical guidance states that different supply outputs must not be paralleled unless the power supplies and system design specifically permit it. Each branch should remain connected to its assigned unit.

How Are Electrical Loads Divided?

Electrical grouping begins with the LED layout inside each letter. Engineering staff record the module type, quantity and rated consumption, then calculate the load for every letter or logo element.

A practical calculation follows five steps:

1. Count the LED modules or measure the LED strip length.
2. Calculate the power used by each letter.
3. Add the loads assigned to each electrical branch.
4. Include controllers or other powered devices where applicable.
5. Select a power supply with suitable reserve capacity.

Power supplies should not operate continuously at their rated maximum. Iduoduo’s engineering reference normally allows about 20%–30% power reserve, adjusted according to the power-supply model, ambient temperature, outdoor exposure, daily operating time, LED load, control equipment and cable length.

Consider an individually mounted sign with a calculated LED load of 320 W.

Calculation	Result
Actual LED load	320 W
Capacity with 20% reserve	384 W
Capacity with 25% reserve	400 W
Capacity with 30% reserve	416 W

A possible arrangement could use two 200 W supplies, with approximately 160 W connected to each unit. The final choice depends on the actual power-supply ratings, available installation space, environmental conditions, certifications and circuit layout.

Electrical groups may be divided by:

• Letter position
• Logo area
• Left and right sides
• Upper and lower rows
• Front illumination
• Halo illumination
• White and colored lighting
• RGB or RGBW zones
• Product segments
• Separate storefront areas

Every branch should identify:

• System voltage
• Connected letters
• Calculated wattage
• Assigned power supply
• Wire type or size
• Polarity
• Connector type
• Circuit number

A useful circuit schedule might read:

Circuit	Letters	Voltage	LED load	Power supply	Control
A	A–E	24V DC	138 W	PSU-1	Main switch
B	F–J	24V DC	142 W	PSU-2	Main switch
C	Logo	24V DC	65 W	PSU-3	Separate switch
D	Halo light	24V DC	84 W	PSU-4	Dimmer

Circuit grouping should also consider the effect of a failure. Placing an entire long façade on one supply means one failed component may darken the complete sign. Dividing the letters into two balanced groups limits the affected area and usually makes troubleshooting easier.

The largest letter does not always need its own supply. A large, open letter may use fewer LED modules than a smaller, dense logo. Power must be calculated from the actual lighting arrangement rather than letter height or total sign width.

How Does Wire Length Affect Voltage?

Low-voltage LED systems are sensitive to cable length. A longer cable has more electrical resistance. Higher current and smaller conductors increase the voltage lost before power reaches the letters.

The effect can be easy to miss during quoting. A power supply may have adequate wattage, yet the final letter still appears dim because the cable between the supply and the sign is too long or too small.

Possible symptoms include:

• Letters farthest from the supply appear dimmer
• One side of the wordmark is brighter than the other
• White LEDs show a slight color shift
• RGB colors do not match across the sign
• Controllers restart or respond unreliably
• Connectors become unusually warm
• Lighting flickers when several zones switch on
• A supply appears overloaded even though the calculated wattage seems acceptable

The relationship between power, voltage and current helps explain the problem:

Current = Power ÷ Voltage

For the same 240 W lighting load:

System voltage	Approximate current
12V DC	20 A
24V DC	10 A

The 24V system carries half the current for the same power. Lower current can reduce the load on cables, terminals and connectors and may help manage voltage drop over longer routes. LED modules, supplies, dimmers and controllers must all match the selected voltage. A 12V LED system cannot be connected to a 24V supply.

Iduoduo’s project facts identify 12V systems as common for smaller channel letters and shorter runs, while 24V systems can suit larger letters, longer routes and projects requiring lower line current. The final selection depends on the approved components rather than a universal size rule.

When cable distance becomes a concern, engineers can consider:

• Moving the power supply closer to the letters
• Dividing one long branch into several shorter branches
• Increasing conductor size
• Using a suitable 24V system
• Reducing the load on each circuit
• Feeding large sections from more than one point
• Improving connector capacity
• Avoiding long letter-to-letter daisy chains

Wire size cannot be selected from wattage alone. The calculation also needs:

• Current
• Operating voltage
• One-way cable length
• Indoor or outdoor use
• Ambient temperature
• Number of cables grouped together
• Installation method
• Connector rating
• Local electrical requirements

A common site mistake is moving the power supply after the sign has already been engineered. For example, the drawing may place a supply 2 m from the letters, but the installer later moves it 12 m away to an electrical room. The original cable size and grouping may no longer be suitable.

Any major change in power-supply position should trigger a review of:

• Cable length
• Cable size
• Circuit load
• Voltage at the farthest letter
• Branch arrangement
• Connector capacity
• Supply quantity

The Iduoduo electrical standard lists larger wire, shorter routes, additional circuits, closer power-supply placement, reduced branch load and suitable 24V systems among the available methods for controlling voltage drop.

How Are Wall Penetrations Protected?

A wall penetration must protect both the electrical cable and the building envelope. The cable should not rub against sharp metal, sit under excessive tension, allow water to follow it indoors, or pass through a hole larger than necessary without proper sealing.

Protection depends on the façade material.

Mounting surface	Main issue to check
Aluminum composite panel	Sharp cut edges and unsupported panel skin
Sheet metal	Abrasion, burrs and corrosion at the opening
Masonry	Rough hole surfaces and water entry
Concrete	Long drilling route and concealed reinforcement
Stone cladding	Panel joints, support system and cracking risk
Render or stucco	Surface damage and waterproof-layer continuity
Timber	Moisture movement and cable protection
Curtain wall	Drainage paths, glazing system and specialist approval

Cable openings may require suitable sleeves, bushings, grommets, glands, conduits or sealants according to the wall system and local installation method. The factory can prepare the letter leads and indicate exit positions, but the installer must select the final wall-sealing detail for the actual building.

For outdoor installations, attention should be given to:

• Downward cable routing where practical
• Drip loops before enclosure entries
• Compatible exterior sealants
• Weather-resistant connectors
• Sealed wire exits on the letter back
• Protection from standing water
• Strain relief
• Drainage around the sign
• Separation between mains and low-voltage wiring

Connector quality is equally important. Iduoduo’s electrical reference lists soldered joints, crimp terminals, plug connectors, screw terminals, waterproof connectors and quick-disconnect fittings. Selection depends on voltage, current, pulling force, waterproofing, maintenance and installation convenience.

A connector should not be chosen simply because it fits the cable. It must also carry the branch current, remain secure during shipping and installation, resist the intended environment and allow practical servicing.

Production inspection should cover:

• Correct polarity
• Wire gauge
• Wire color
• Insulation
• Connector rating
• Secure crimping or soldering
• Pull protection
• Waterproofing
• Branch identification
• Cable fixation
• Wire exit length
• Wire exit position

After assembly, illuminated products should be checked for output, polarity, function, flicker, controls, power-supply temperature and wiring stability. Iduoduo performs a 100% lighting inspection and a 72-hour pre-shipment electrical stability test, observing the supplies, LEDs, wiring, controllers, brightness, color, flicker and abnormal temperature rise.

Factory testing confirms the prepared sign system, but it cannot verify a building circuit that has not yet been connected. The local qualified electrician remains responsible for the AC supply, breaker, grounding, high-voltage wiring, final connection and local inspection.

A reliable connection plan therefore needs more than a bag of wires and power supplies. It needs a circuit schedule, labeled cables, defined wire exits, matched voltage, calculated load, power reserve, suitable conductor sizes, protected penetrations and a clear division between factory-prepared low-voltage work and site electrical work.

Which Site Conditions Affect Placement?

Power-supply placement depends on rear access, wall construction, cable distance, moisture, heat, maintenance clearance, available AC power and local electrical rules. A position may look convenient on an elevation drawing but fail during installation because of concrete, pipes, sealed ceilings, hot cavities or inaccessible finishes. The location should be confirmed from site measurements and interior access—not from the storefront photograph alone.

Before approving the production drawing, record the following site information:

Site item	Information required	Why it affects the power supply
Wall construction	Material, depth, framing and internal cavity	Determines whether cables and supplies can sit behind the façade
Rear access	Open, removable, limited or completely sealed	Determines installation and future replacement access
AC power point	Position, input voltage and circuit arrangement	Determines the high-voltage route to the power supply
Sign-to-supply distance	Horizontal and vertical distance in meters	Affects cable size, voltage drop and circuit grouping
Indoor conditions	Heat, humidity, dust, grease and water pipes	Affects reliability, ventilation and enclosure selection
Outdoor exposure	Rain, sunlight, salt, snow and standing water	Affects power-supply protection and installation method
Maintenance route	Access door, ceiling tile, hatch or cabinet	Determines whether a failed unit can be replaced
Mounting method	Direct mount, raceway or backer panel	Changes the available space and number of wall penetrations
Local requirements	Permit, grounding, disconnect and inspection	Affects the final electrical installation

Iduoduo’s installation standard requires the power supply to be mounted in a dry, ventilated and serviceable location. It should not sit in standing water, remain under continuous sun, become permanently sealed or be placed an unreasonable distance from the sign. Input voltage, power-supply quantity, switches, controls, wiring distance and access space should be confirmed before production.

Is There Access Behind the Façade?

Rear access is one of the first conditions to check for individually mounted channel letters. The clean exterior appearance usually depends on low-voltage wires passing directly through the façade. Those wires still need somewhere to go, and the power supplies must be mounted where an installer can connect and later service them.

Rear-access conditions usually fall into three groups:

Rear-access condition	Typical arrangement	Main concern
Full access	Open interior wall, service room or accessible bulkhead	Usually suitable for direct mounting
Limited access	Suspended ceiling, narrow cavity or removable cabinet	Cable route and service opening need precise planning
No rear access	Solid wall, sealed façade, glass system or inaccessible tenancy	Raceway, backer panel or external enclosure may be more practical

Full access means the installer can reach the rear side of the complete letter area. Each letter lead can pass through the wall and connect to clearly labeled branch circuits. Power supplies may be distributed near the left and right sides of a long wordmark, helping keep low-voltage routes shorter.

Limited access does not automatically prevent direct mounting. It does, however, require more accurate drawings. A ceiling tile 1 m above the sign may provide access, while a narrow gap behind fixed cabinets may not. The installer needs enough room to position tools, secure the supply, connect terminals and remove the unit later.

No rear access changes the project more significantly. Common examples include:

• Solid reinforced concrete walls
• Thick masonry without an internal cavity
• Stone façades with restricted drilling
• Sealed architectural panels
• Glass curtain walls
• Façades backed by another occupied unit
• Exterior walls with permanent interior finishes
• Parapets without a service route

In these situations, trying to hide everything behind the wall can create unnecessary drilling, exposed interior conduit or extensive repair work. A raceway can centralize wiring and power supplies behind the letters. A backer panel can create a controlled cable space. A separate outdoor enclosure may also work when indoor access is impossible.

The site survey should measure more than the overall sign area. Record:

• Distance from the letter backs to the accessible space
• Position and size of any access hatch
• Maximum opening available for replacing the power supply
• Distance from the power-supply position to the farthest letter
• Location of structural columns and framing
• Position of AC power
• Space occupied by ducts, pipes or insulation
• Future cabinets, displays or ceiling finishes

Access should be checked from the technician’s position, not only from the drawing. A power supply may be visible through a small hatch but still impossible to remove because the opening is narrower than the unit.

Which Wall Types Need Special Planning?

Wall material affects drilling, anchoring, cable routing, water sealing and access. The same channel-letter set may require a completely different power arrangement when moved from an aluminum storefront to concrete, stone or glass.

Wall type	Hidden issue	Likely effect on placement
Framed drywall	Studs, insulation and concealed cables	Supply may fit in the cavity, but access and fastening need confirmation
Aluminum composite panel	Thin surface with supporting rails behind it	Wires can pass through, but power supplies need a solid mounting surface
Solid concrete	No usable cavity and difficult cable routing	Raceway or indoor surface conduit may be required
Brick or block	Rough drilling route and possible hollow sections	Penetrations, anchors and sealing need site selection
Stone cladding	Panel joints, brackets and cracking risk	Drilling positions require coordination with the façade contractor
Timber wall	Moisture movement and combustible construction	Cable and power-supply mounting require appropriate protection
Curtain wall	Internal drainage and pressure-equalized chambers	Ordinary drilling may damage the façade system
Glass	No conventional hidden wire route	Backer panels, stand-offs or adjacent structural areas are often needed
Decorative slat wall	Finish may not provide structural support	Cables and fixings must reach the supporting wall behind it

A framed wall can appear ideal because it contains a cavity. In practice, the cavity may contain insulation, electrical cables, steel studs or fire barriers. The power supply should not be left loose inside the wall or covered by insulation. It needs a secure mounting position and a service opening.

Aluminum composite panels are common on commercial storefronts. The visible panel may be only a thin outer skin fixed to rails or framing. Channel letters and power supplies cannot rely on the panel surface alone for structural support. The installer should identify the framing and the internal service space before drilling.

Solid concrete often leads to a different arrangement. Low-voltage wires may need to pass through drilled channels, enter from the side or run through a surface-mounted structure. When the interior concrete face is visible and cannot be altered, a raceway may reduce installation work despite adding a visible structure behind the letters.

Stone and tile façades need careful drilling positions. A wire exit shown at the center of a letter may land close to a stone edge or support bracket. Moving the exit during installation can interfere with internal LEDs, mounting studs or letter backs. Stone joints, panel thickness and support locations should therefore be shared before the final shop drawing.

Curtain walls require the highest level of façade coordination. Internal chambers may manage air pressure and water drainage. An uncontrolled hole can damage the system even when the cable itself is sealed. The curtain-wall contractor or specialist installer should approve the penetration area and connection method.

Iduoduo’s installation requirements call for checks behind the drilling area, including electrical lines, water pipes, framing, curtain-wall structures, stone joints, glazing, power points, stud positions and anchoring depth.

Is the Location Dry and Ventilated?

A power supply generates heat while converting building AC power to the 12V or 24V DC used by the LEDs. Heat and moisture are two of the most common site conditions affecting reliability.

An indoor location should not automatically be treated as dry. Possible sources of moisture include:

• Roof leaks
• Condensation on HVAC pipes
• Fire-sprinkler lines
• Plumbing above the ceiling
• Humid kitchens or wash areas
• Exterior-wall condensation
• Wet cleaning around floor-level cabinets
• Water entering through unsealed wall holes

An outdoor location presents additional concerns:

• Direct rain
• Wind-driven water
• Standing water
• Continuous sunlight
• Salt air
• Snow or ice
• Dust and insects
• Corrosive industrial conditions

The selected area should be inspected during normal building operation. A ceiling cavity may feel dry during construction but later receive condensation from an air-conditioning duct. A cabinet may look cool while empty but become hot after other electrical equipment is installed.

Ventilation requirements become more important when several power supplies share one enclosure. The units should not be stacked tightly unless the approved installation method allows the arrangement. Enough internal space should remain for:

• Air movement
• Cable bends
• Terminal access
• Separation between connections
• Heat release
• Replacement of one unit without removing all others

Iduoduo’s troubleshooting reference lists long-term full loading, insufficient ventilation, sealed spaces, high ambient temperature, stacked supplies, abnormal input, short circuits, dust and grease as possible causes of power-supply overheating.

A practical site risk check can be organized as follows:

Condition	Lower-risk position	Higher-risk position
Water	Dry service cabinet above floor level	Floor-level box near drainage or cleaning water
Ventilation	Open service space with reasonable air movement	Small sealed cavity filled with insulation
Sun exposure	Shaded exterior enclosure	Metal box facing continuous afternoon sun
Equipment spacing	Units securely mounted with working space	Several supplies stacked together
Contamination	Clean electrical area	Kitchen grease, heavy dust or workshop debris
Temperature	Stable indoor utility area	Roof void or unventilated exterior cabinet
Cable entry	Protected, downward-oriented entry	Upward-facing opening collecting water

Outdoor power supplies need protection suited to the environment, but a protected unit should still not be placed directly on a surface where water collects. The enclosure design should consider mounting orientation, cable entries, ventilation, terminals, drainage, sunlight and maintenance.

Water can also enter through the installation holes rather than through the sign. Cable holes, stud holes, raceway fasteners and backer-panel fixings should be sealed using materials compatible with the wall, cable and local climate. An illuminated letter can remain watertight while an unsealed wall penetration allows water into the building.

Can the Power Supply Be Serviced?

Power supplies are replaceable electrical components. Their location should allow a technician to inspect terminals, check output voltage, read the model label and replace the unit without dismantling the whole sign or cutting finished walls.

A serviceable position normally provides:

• A removable panel, hatch, tile or enclosure cover
• Enough opening width to remove the supply
• A safe position for tools and testing equipment
• Visible labels for input and output circuits
• Access to terminals without pulling cables excessively
• Enough cable length for reconnection
• A dry working area
• A route not blocked by permanent furniture or displays

Maintenance access often becomes harder after a store opens. A ceiling hatch may later sit above a fixed checkout counter. A wall panel may become covered by display shelving. A utility cabinet may be filled with stock. The sign plan should therefore consider the completed commercial space rather than only the empty construction site.

Access arrangements can be rated during the site survey:

Access level	Example	Maintenance effect
Good	Labeled electrical cabinet at reachable height	Routine inspection and replacement
Acceptable	Removable ceiling tile with clear working space	Ladder access may be needed
Restricted	Small hatch behind movable furniture	Longer service time
Poor	Fixed wall panel or sealed plasterboard ceiling	Cutting and repair may be required
Unacceptable	Supply permanently buried in the wall	Replacement may require major demolition

Service labels are especially important when several supplies are used. A long wordmark might have four supplies serving different letter groups. Labeling the supplies as PSU-1, PSU-2, PSU-3 and PSU-4 is useful only when the wiring diagram also shows which letters belong to each group.

Useful records include:

• Power-supply manufacturer and model
• Input voltage range
• Output voltage
• Rated power
• Connected load
• Letters served
• Cable route
• Branch number
• Controller or dimmer assignment
• Installation position
• Access method
• Testing date

Power-supply maintenance should include checks for abnormal temperature, sound, flicker, moisture, terminal condition, cable condition, ventilation, corrosion, service-box condition and labeling. Replacement units should match the required input, output, wattage, operating environment and requested certification.

A location should be rejected when the only replacement method involves removing several channel letters from the exterior. For signs installed high above ground, exterior removal may require a lift, road control or temporary closure. An accessible indoor supply position can significantly reduce future service work.

Do Local Codes Affect the Location?

Local electrical and building requirements can affect where the power supply is mounted, how AC power reaches it, which enclosure is used and who is allowed to complete the final connection.

The sign factory can prepare the low-voltage LED system, match power supplies, label wires, position wire exits and test the sign. The building-side electrical work remains site-specific.

Local electrical review may cover:

• Building AC voltage
• Circuit and breaker capacity
• Disconnecting method
• Grounding
• High-voltage cable type
• Junction boxes
• Separation of mains and low-voltage wiring
• Power-supply mounting
• Outdoor enclosure selection
• Accessibility
• Wall penetrations
• Fire-rated walls
• Permits
• Inspection and final acceptance

The power supply may accept a broad input range, but the model label must still be checked against the actual building voltage. The installer should also confirm grounding, plug or hardwired connection, switch, timer, photocell, dimmer and control arrangement.

Certification should be discussed early. A recognized power supply or electrical component does not automatically make the complete installed sign certified. The final system also includes the building circuit, breaker, grounding, mains wiring, enclosures, mounting method and local connection.

Iduoduo’s documented responsibility covers the low-voltage LED system, power-supply matching, controllers, dimmers, wire exits, internal wiring, polarity, testing, labels and agreed electrical records. A qualified local electrician remains responsible for building AC input, breakers, distribution, grounding, wall wiring, junction boxes, high-voltage connections, power-supply fixing, local permits and final inspection.

Before production, the local sign company or electrician should answer the following questions:

• Is the building supply 110V, 120V, 220V, 230V or another value?
• Will the sign be hardwired or connected through an approved plug?
• Is a dedicated sign circuit available?
• Where is the circuit isolated?
• Is grounding available at the proposed supply position?
• Must the supply sit inside a listed or project-approved enclosure?
• Is the power supply accessible under local rules?
• Are wall penetrations permitted in the proposed area?
• Does the property manager require a specific mounting method?
• Who will arrange the permit and final inspection?

Site conditions can change the recommended sign structure even after the visual design is approved. Direct-mounted letters may suit a framed storefront with full rear access. The same letters may need a raceway on concrete, a backer panel on slatted walls or a separate enclosure on a roof-mounted façade.

The safest approach is to confirm the hidden conditions before the letters enter production. Wall photographs, interior photographs, section drawings, measured cable distances, AC power location and the proposed service opening provide far more value than an exterior elevation alone. A clear site record allows the power supplies, wire exits, circuits and mounting structure to be engineered around the actual building instead of being corrected during installation.

What Should Be Confirmed Before Production?

Before individually mounted channel letters enter production, confirm the building power, input voltage, LED operating voltage, power-supply location, service access, cable distance, electrical grouping, wire exits, mounting method, wall construction, controls, certification needs and final installation responsibility. Every decision should appear in the approved drawing. Leaving electrical details for installation day often leads to extra drilling, visible cables, delayed opening dates or costly rework.

A complete pre-production record should answer the following questions:

Item	Information to approve	Risk when left unclear
Building supply	Voltage, frequency, grounding and circuit location	Wrong power supply or unavailable connection point
LED system	12V or 24V DC	Incompatible LEDs, controllers or power supplies
Power-supply position	Exact room, cabinet, ceiling or enclosure	Excessive cable distance or no maintenance access
Electrical load	Wattage by letter and circuit	Overloaded supply, heat or unstable lighting
Power-supply quantity	Unit rating, number and reserve	Uneven load or single-point failure
Wire exits	Position, direction, length and labels	Incorrect drilling or exposed wiring
Mounting method	Direct mount, raceway or backer panel	Wrong letter backs, templates or wiring route
Wall condition	Material, depth, cavity and rear access	Installation cannot follow the approved layout
Controls	Switch, timer, photocell, dimmer, RGB or RGBW	Missing control parts or incorrect wiring
Documentation	Elevation, section, electrical and mounting drawings	Installer must guess how parts connect
Responsibility	Factory work and local electrical work	Gaps between product supply and site installation
Destination market	Country, plug, component documents and local review	Incorrect components or delayed approval

Iduoduo’s channel-letter project requirements include the logo, size, lighting method, letter depth, indoor or outdoor location, LED color or CCT, voltage, power-supply certification, mounting method, raceway or backboard, wire exits, wall type, weather-protection level, destination country, packaging and project schedule.

Where Is Primary Power Available?

The first electrical question is not how many power supplies are needed. It is where usable building AC power is located.

A note saying “power is available” gives too little information. The installation team needs the exact point from which the sign circuit will be connected. It may be inside an electrical cupboard, above a suspended ceiling, behind the storefront wall, near a roof parapet or inside a landlord-controlled service area.

Record the following details before approving the sign drawings:

• Exact AC connection point
• Distance from the connection point to the proposed power-supply position
• Available input voltage
• Supply frequency
• Grounding availability
• Dedicated or shared circuit
• Circuit and breaker information
• Existing switch or isolator position
• Timer, photocell or building-control connection
• Hardwired or plug-connected arrangement
• Person responsible for the final connection
• Access restrictions imposed by the property manager

The AC power point and the LED power supplies do not have to be in the same place. Building AC may travel to a serviceable enclosure close to the sign, where the power supplies convert it to low-voltage DC. The low-voltage cables then run from the supplies to the individual letters.

Moving the power supplies closer to the building electrical cupboard may shorten the AC route but lengthen the 12V or 24V cable route. Moving them closer to the letters may improve low-voltage performance but require more site-side electrical work. The final position should balance both routes rather than minimizing only one.

Consider a storefront where the building circuit is 14 m from the letter area. Placing every power supply in the distant electrical room may create long low-voltage runs. A more practical arrangement may extend the approved AC circuit to an accessible cabinet 2 m behind the sign, then distribute shorter low-voltage branches to the letters. The final arrangement must be reviewed by the local electrician.

A site photograph should mark both the sign position and the available power point. Interior photographs are equally important. An exterior elevation cannot reveal whether the intended route crosses a concrete beam, fire-rated wall, tenant boundary, ventilation duct or inaccessible ceiling.

The following record is useful for production approval:

Primary-power record	Example entry
Destination	United States
Building input	120V AC, 60Hz
Connection method	Hardwired
Circuit location	Electrical cupboard behind sales area
Proposed supply location	Accessible ceiling above storefront
AC route	Approximately 6 m
Control	Existing timer
Final connection	Local licensed electrician

The values above are only an example. The actual building conditions must be documented for each location.

For multi-store projects, do not assume every location has the same electrical arrangement. One branch may have 120V AC with ceiling access, while another has 230V AC, a solid concrete wall and no rear service space. The visual channel-letter standard can remain consistent, but the electrical and mounting package may need separate versions.

Which Input Voltage Is Required?

Three electrical values are often mixed together during early discussions:

• Building AC input voltage
• Power-supply DC output voltage
• LED operating voltage

The building may provide 120V, 220V, 230V or another AC input. The power supply converts the building input to the low-voltage DC required by the letters, commonly 12V or 24V. A channel letter marked 24V DC must never be connected directly to a 120V or 230V building circuit.

Before production, approve:

• Building input voltage
• Input frequency, commonly 50Hz or 60Hz
• Power-supply input range
• DC output voltage
• LED operating voltage
• Dimmer or controller voltage
• Grounding requirement
• Plug type or hardwired arrangement
• Indoor or outdoor power-supply model
• Requested component certification or documentation

Some power supplies support a broad input range such as 100V–240V AC, but compatibility must be checked against the label and specification of the actual model. One previous project using a wide-input supply does not prove that every available unit can operate worldwide.

Every low-voltage part must match the same system voltage:

Component	Required confirmation
LED modules	12V or 24V
Power-supply output	Must match the LEDs
Dimmer	Must support the selected voltage and load
RGB controller	Must match LED voltage and channel arrangement
RGBW controller	Must support the required four-channel system
Connectors	Must carry the branch current
Cables	Must suit current, length and environment
Labels	Must state voltage and polarity clearly

A 12V supply connected to 24V modules may produce weak or incomplete lighting. A 24V supply connected to 12V modules can damage the LEDs. Mixing 12V and 24V parts within an unlabeled shipment creates an avoidable installation risk.

For repeat orders, confirm voltage again even when the logo, size and finish remain unchanged. A chain brand may reorder the same letters for the United States, Europe, the United Kingdom and Australia. The physical letter construction may remain similar, but input power, plugs, power-supply documents and installation methods can differ.

Iduoduo configures sign electrical systems according to LED load, 12V or 24V operation, cable length, voltage drop, controls, installation environment and destination market. Available arrangements include 110V–240V input power supplies, project-specific plugs, hardwiring and market-related component documents when specified. Certified components do not automatically certify the complete installed sign.

How Many Power Supplies Are Needed?

Power-supply quantity should be calculated from the approved LED layout, not estimated from the overall sign width or number of letters.

Two sets of letters with the same overall width can use different amounts of power. A dense logo with wide illuminated areas may contain far more LED modules than a thin wordmark. Front-lit, halo-lit and front-and-halo-lit letters also have different electrical loads.

The calculation normally follows five steps:

1. Record the LED model and rated consumption.
2. Count the modules or calculate the LED strip length in every letter.
3. Add the load for each proposed electrical group.
4. Include controllers and other powered accessories where applicable.
5. Select power supplies with a reasonable operating reserve.

Iduoduo’s engineering reference commonly allows around 20%–30% power reserve, adjusted according to the supply model, ambient temperature, outdoor exposure, operating hours, LED load, control system and cable length. A supply should not be planned to operate continuously at its rated maximum.

An illustrative calculation may look like the following:

Letter group	Calculated LED load
Letters A–D	92 W
Letters E–H	104 W
Letters I–L	86 W
Logo symbol	58 W
Total LED load	340 W

With a 25% planning reserve:

340 W × 1.25 = 425 W

A possible arrangement could divide the sign across three supplies rather than using one central unit:

Power supply	Connected area	Connected load	Rated capacity	Approximate use
PSU-1	Letters A–D	92 W	120 W	77%
PSU-2	Letters E–H	104 W	150 W	69%
PSU-3	Letters I–L and logo	144 W	200 W	72%

The figures are an example of the grouping process, not a universal specification. Final unit sizes depend on available models, operating temperature, requested certification, enclosure conditions, wiring distance and installation layout.

Several smaller supplies can provide practical advantages:

• Shorter low-voltage cable runs
• Lower voltage-drop pressure
• Easier left-and-right zoning
• Separate control of a logo and wordmark
• Separate front and halo lighting
• Faster fault isolation
• Less sign area affected by one failed unit
• Easier replacement when service spaces are distributed

Additional supplies also create extra work:

• More AC connections
• More low-voltage branches
• More labels
• More mounting space
• More heat inside an enclosure
• More commissioning checks
• Higher component cost

The best quantity is not necessarily the fewest or the most. It is the number that gives balanced loading, manageable wiring and practical maintenance.

Each supply should be identified on the drawing and on the physical unit. A notation such as “four power supplies included” is not enough. The installer needs to know which letters connect to PSU-1, PSU-2, PSU-3 and PSU-4.

The project record should include:

• Power-supply manufacturer and model
• Input range
• DC output
• Rated wattage
• Quantity
• Connected letter group
• Calculated load
• Reserve
• Installation position
• Controller assignment
• Cable and branch reference

Iduoduo’s electrical records can preserve LED voltage, power-supply model, rated power, quantity, input voltage, plug, controller, wire specification, electrical branches, wiring diagrams, test records and requested certification documents.

Where Should Wire Exits Be Placed?

Wire exits determine where the installer drills, how the letters align and whether the cable can reach the hidden service area. Their positions must be approved before the backs, LEDs, templates and mounting hardware are completed.

For each letter, confirm:

• Rear, side or bottom wire exit
• Horizontal and vertical location
• Distance from the letter edge
• Cable length outside the letter
• Cable type and number of conductors
• Positive and negative identification
• Separate circuits for front and halo illumination
• RGB or RGBW control wires
• Corresponding hole on the installation template
• Power-supply or branch number
• Indoor or outdoor sealing requirement

Rear exits are common for individually mounted letters because they allow cables to pass directly through the façade. A side or bottom exit may be required when the letters connect to a raceway, backer panel, exposed conduit or nearby service box.

The wall structure must be considered before the exit position is frozen. A visually convenient location may align with:

• Steel framing
• Reinforced concrete
• A stone panel edge
• Curtain-wall mullions
• Window framing
• Electrical cables
• Plumbing
• Fire barriers
• Structural brackets
• Drainage channels

Moving a wire exit after manufacturing may require changes to the letter back, LED arrangement, cable length, waterproofing and drilling template. A small drawing correction made early is far less expensive than opening completed letters at the job site.

For repeated letters, cable labels prevent confusion. A sign containing several identical “A,” “E” or “O” letters may have different wire lengths or branch assignments. Label each unit by position rather than letter shape alone.

Letter position	Product label	Wire label	Circuit
First letter	L01	L01-A	PSU-1
Second letter	L02	L02-A	PSU-1
Center logo	G01	G01-B	PSU-2
Final letter	L10	L10-C	PSU-3

The same references should appear on:

• Elevation drawing
• Mounting template
• Wiring diagram
• Physical cables
• Power supplies
• Packing list
• Installation guide

Outdoor wire exits also require a sealing plan. The cable should not pass over a sharp metal edge, remain under tension or create a direct water path into the wall. Final sleeves, glands, sealants, conduits or façade-specific waterproof details are selected by the local installation team according to the actual wall.

Which Drawings and Responsibilities Must Be Approved?

Production should begin from a frozen approval package rather than an image, quotation and message history spread across several communication channels.

The minimum drawing set for individually mounted channel letters normally includes:

Drawing	Information it should show
Overall elevation	Total size, letter height, spacing, logo position and baseline
Product section	Face, return, back, depth, LEDs and mounting structure
Mounting drawing	Studs, screws, brackets, raceway or backer panel
Wire-exit drawing	Exit position, direction, cable length and labels
Electrical drawing	Voltage, supplies, branches, loads and controls
Site interface drawing	Wall type, penetrations, access and power position
Installation template	Full-scale or segmented drilling pattern
Access drawing	Power-supply location and service method

The approved specification should also state:

• Letter type and lighting method
• Face and return materials
• Letter depth
• Indoor or outdoor use
• LED color or color temperature
• 12V or 24V operation
• Input voltage
• Power-supply model and quantity
• Electrical groups
• Cable and connector arrangement
• Dimmer, timer, photocell or controller
• Mounting method
• Raceway or backer-panel requirements
• Wire-exit positions
• Wall material
• Waterproofing level
• Destination country
• Component-document requirements
• Packaging arrangement
• Required delivery date

Iduoduo converts approved visual and architectural information into production-ready signage through manufacturability review, shop drawings, sections, electrical drawings, mounting drawings, BOMs, finish schedules, revision control, samples and first-article approval. Approved results are transferred into the final production, QC, mounting and packaging records.

The final approved version should carry a revision number and date. Changes to size, depth, mounting, voltage, wire exits or power-supply position after approval may affect several production steps at once.

A clear responsibility boundary is equally important.

Iduoduo can prepare and confirm:

• Internal LED layout
• Low-voltage operating system
• Power-supply matching
• Electrical grouping
• Controllers and dimmers
• Internal wiring
• Cable polarity
• Wire exits
• Letter labels
• Mounting preparation
• Templates
• Factory testing
• Electrical records
• Packing of power supplies and accessories

The local sign company, contractor or qualified electrician should confirm and complete:

• Building AC supply
• Circuit and breaker suitability
• Grounding
• High-voltage wiring
• Junction boxes
• Disconnecting method
• Power-supply fixing at the site
• Wall drilling and penetrations
• Façade sealing
• Structural anchoring
• Local permit
• Inspection
• Final acceptance

Certified power supplies or components do not automatically certify the complete sign installation. Building power, grounding, high-voltage wiring, permits and local inspection remain the responsibility of qualified local electricians.

Before releasing the production order, conduct one final cross-check:

• Does the approved voltage match the destination?
• Does every LED component match the DC system?
• Is every supply assigned to a letter group?
• Is the connected load within the planned capacity?
• Is the power-supply position accessible?
• Are measured cable distances available?
• Are wire exits dimensioned?
• Does the template match the final drawing?
• Does the mounting method match the wall?
• Are separate lighting zones identified?
• Are all cables and supplies labeled?
• Are outdoor penetrations assigned to the installer?
• Is final AC work assigned to a qualified electrician?
• Has the final revision been formally approved?

Production can then proceed using one consistent set of drawings, loads, labels and installation assumptions. Iduoduo performs electrical and functional checks followed by a 72-hour pre-shipment stability test for illuminated signs, recording power-supply operation, wiring, LEDs, controls, flicker, temperature rise, color and brightness.

A few minutes spent confirming the electrical package before production can prevent hours of drilling changes, cable replacement and troubleshooting later. The goal is simple: every letter arrives with a known position, every wire has a destination, every power supply has an accessible home, and the installer can reproduce the factory-tested arrangement without guessing.

What Should Be Confirmed Before Production?

Before individually mounted channel letters enter production, the electrical and installation plan should be specific enough for the factory, sign company, installer and electrician to work from the same information. A logo file and overall dimensions are not enough. The approved package should show where AC power is available, where each power supply will sit, how far the low-voltage cables will run, which letters belong to each circuit, where every wire exits, and how the equipment will remain accessible after the storefront is finished.

Most installation problems do not start with the LED modules. They start with one missing site detail:

• The proposed supply position is behind a concrete beam.
• The ceiling shown as accessible is later sealed with plasterboard.
• A 12V system is shipped for a 24V project.
• The power supply is moved farther away without recalculating cable size.
• Wire exits do not match the usable wall cavity.
• Front and halo lighting are combined even though separate control is required.
• A raceway is added after production, but the letter backs were prepared for direct mounting.
• The factory drawing and installer drawing use different revisions.

A useful approval package should answer four practical questions for every electrical item:

Question	Required answer
What is it?	Component model, voltage, wattage, cable or connector type
Where does it go?	Letter, circuit, enclosure, ceiling zone or wall position
How is it reached?	Wire route, service hatch, removable cover or access panel
Who completes it?	Factory, sign installer, electrical contractor or property team

The project should not be released because everyone “understands the general arrangement.” Production should begin when the arrangement can be measured, labeled, tested, packed and reproduced on site.

Iduoduo’s engineering process covers LED layout, power capacity, wiring, mounting holes, wire exits, backboards, raceways, waterproofing and installation preparation. Approved information is transferred into shop drawings, electrical drawings, mounting specifications, production files, QC records and packing requirements.

Where Is Primary Power Available?

The first point to confirm is the actual building AC connection location. “There is power behind the wall” is not precise enough. The site team should identify the room, cabinet, ceiling area, junction point or circuit from which the sign will receive power.

Mark the power position on an interior photograph or site plan. Include dimensions from fixed architectural references rather than temporary objects. A note such as “power is near the door” can become useless after shelving, ceilings and finishes are installed.

The primary-power record should include:

• Building input voltage
• Frequency
• Dedicated or shared circuit
• Approximate circuit capacity
• Breaker location
• Grounding availability
• Isolation or disconnect point
• Existing switch, timer or photocell
• Hardwired or plug-connected arrangement
• Distance to the planned power-supply position
• Access restrictions
• Final connection responsibility

A practical record may look like the following:

Primary-power item	Example project entry
Building input	120V AC, 60Hz
Sign circuit	Dedicated circuit
Breaker location	Rear electrical cupboard
Proposed supply position	Accessible ceiling above storefront
AC route	Approximately 7 m
Sign control	Existing time switch
Connection method	Hardwired
Final connection	Local licensed electrician
Rear access	Removable ceiling tiles
Access height	Approximately 3.2 m above floor

The figures are illustrative. Every store requires its own site record.

The AC connection and the LED power supplies do not always occupy the same location. The building circuit may terminate in an electrical cupboard while the LED supplies sit closer to the letters in an accessible ceiling or service enclosure. AC wiring then runs from the cupboard to the supply position, and low-voltage wiring continues from the supplies to the letters.

Choosing the location requires balancing two distances:

• The AC route from the building circuit to the power supplies
• The DC route from the power supplies to the channel letters

Placing the supplies beside the electrical panel may simplify the AC work but create a 15 m low-voltage run. Moving them to a service space 2 m behind the letters may shorten the DC route and reduce voltage-drop pressure, although the electrician must extend the approved AC circuit farther.

Consider a 7 m-wide storefront wordmark. The electrical room is 18 m away, but a removable ceiling area is available directly behind the sign. Keeping all supplies in the electrical room may create long DC circuits and more cable. Installing the supplies in the ceiling area may be more practical, provided the location is dry, ventilated, securely mounted and reachable.

The installer should also confirm whether the proposed route crosses:

• Fire-rated walls
• Tenant boundaries
• Structural beams
• Mechanical rooms
• Restricted landlord areas
• Wet-service zones
• Fixed ceilings
• Security shutters
• Curtain-wall chambers
• Outdoor-to-indoor transitions

A route crossing a fire-rated partition may require a site-specific penetration and sealing method. A route entering another tenancy may be unacceptable even when the physical distance is short. Such conditions cannot be solved from the sign elevation alone.

For a chain-store rollout, electrical details should be recorded store by store. The logo may remain identical, but the installation package may vary.

Store condition	Possible project response
Rear access and nearby AC	Individually mounted letters with remote indoor supplies
Solid concrete wall	Raceway or surface-routing review
Glass storefront	Backer panel or adjacent structural mounting area
Sealed ceiling	Dedicated accessible electrical enclosure
Long DC route	Relocate supplies, divide circuits or review 24V operation
Outdoor-only access	Protected and serviceable exterior enclosure

The final AC circuit, breaker, grounding and mains connection remain site responsibilities. The factory can prepare the matched low-voltage sign system, but it cannot verify an unseen building circuit.

Which Input Voltage Is Required?

The approved documents should separate three values that are often confused:

1. Building AC input voltage
2. Power-supply DC output voltage
3. LED operating voltage

A building may provide 120V, 220V or 230V AC. The power supply converts the building input to low-voltage DC, commonly 12V or 24V for channel-letter lighting. The LED modules must match the DC output.

A 24V channel-letter set must not be connected directly to 230V building power. The 24V value belongs to the output side of the power supply, not the building circuit.

Before production, confirm the following:

Electrical item	Information required
Building power	AC voltage and frequency
Power-supply input	Approved input range
Power-supply output	12V DC or 24V DC
LED modules	Matching operating voltage
Dimmer	Voltage and load compatibility
RGB/RGBW controller	Voltage, channels and control method
Connectors	Current capacity and environmental suitability
Plug	Type required for the destination
Grounding	Building and enclosure requirements
Component documents	Certification or test documents requested

Every powered component should match the selected system. A 24V supply, 12V LED modules and 12V dimmer do not form a compatible package even when the connectors physically fit.

Voltage confirmation should cover more than the country name. Commercial buildings may contain several electrical systems, and renovation projects may not follow the most common national arrangement. The site electrician should confirm the actual circuit rather than relying only on assumptions such as “United States means 120V” or “Europe means 230V.”

Frequency should also be recorded where relevant. Many modern supplies can accept both 50Hz and 60Hz, but compatibility should be verified from the actual product label and technical specification.

A basic electrical approval schedule can prevent mixed specifications:

Item code	Input	Output	Connected equipment	Quantity
PSU-01	120V AC	24V DC	Letters L01–L05	1
PSU-02	120V AC	24V DC	Letters L06–L10	1
PSU-03	120V AC	24V DC	Logo G01	1
DIM-01	24V DC	24V DC	Halo-light circuit	1

A multi-country rollout needs separate electrical versions even when the visible sign remains unchanged.

Market version	Possible changes to confirm
United States	Input, component documentation, hardwiring and local sign requirements
United Kingdom	Input, plug or hardwiring, isolation and local installation
European Union	Input, requested component documentation and local acceptance
Australia	Input, plug or hardwiring and installer requirements
Middle East	Input, heat exposure, enclosure and local power conditions

A broad-input power supply may support several markets, but the approved model must be checked. Do not assume every supply available in the factory accepts the same input range.

The sign package should carry clear labels showing:

• Power-supply input
• DC output
• LED voltage
• Polarity
• Circuit number
• Connected letters
• Controller assignment

Voltage should also be confirmed again for repeat orders. A saved drawing may belong to a previous country, store or power arrangement. Reusing the old file without checking the destination can result in compatible letters but incompatible electrical accessories.

Iduoduo supports project-specific voltage, power-supply, plug, controller, dimming and wiring configurations. Destination-market requirements are confirmed as part of the electrical and installation review rather than treated as one universal arrangement.

How Many Power Supplies Are Needed?

The number of power supplies should come from the final LED layout and circuit plan. Overall sign width, letter height and letter count provide only rough context.

A wide letter does not always consume more power than a smaller logo. Electrical load depends on:

• Illuminated area
• Stroke width
• Letter depth
• LED module type
• Number of modules
• Module wattage
• Front-lit or halo-lit construction
• Required brightness
• Single-color or RGB/RGBW lighting
• Cable length
• Daily operating time
• Ambient temperature
• Power-supply enclosure conditions

The basic calculation begins with the LED load.

For example:

Sign section	LED quantity	Rated power per LED	Calculated load
Letters L01–L04	46 modules	1.2 W	55.2 W
Letters L05–L08	58 modules	1.2 W	69.6 W
Letters L09–L12	52 modules	1.2 W	62.4 W
Logo G01	38 modules	1.2 W	45.6 W
Total	194 modules	—	232.8 W

The table is an example only. Actual consumption should follow the approved LED specification.

A working reserve is then added. Iduoduo’s project engineering commonly considers a reserve of around 20%–30%, adjusted for the power-supply model, temperature, outdoor exposure, working hours, control equipment and cable conditions.

Using a 25% reserve:

232.8 W × 1.25 = 291 W

The project could use one larger supply, two balanced supplies or several smaller units. The most practical answer depends on circuit distance, available models, enclosure size and service access.

One possible arrangement:

Supply	Connected section	Calculated load	Rated capacity	Approximate loading
PSU-1	Letters L01–L06	91 W	150 W	61%
PSU-2	Letters L07–L12	96 W	150 W	64%
PSU-3	Logo G01	45.6 W	75 W	61%

Another arrangement may use two units:

Supply	Connected section	Calculated load	Rated capacity	Approximate loading
PSU-1	Letters L01–L06	91 W	150 W	61%
PSU-2	Letters L07–L12 and logo	141.6 W	200 W	71%

Neither arrangement is automatically superior. The second uses fewer supplies. The first isolates the logo and may reduce cable length or simplify separate control.

The electrical grouping should answer the following:

• Which letters connect to each supply?
• What is the calculated load on each unit?
• What reserve remains?
• Where will each unit be mounted?
• How long is the farthest DC cable?
• Does one supply operate a separate visual element?
• Will one failure darken the entire sign?
• Can every unit be accessed for replacement?
• Is there enough enclosure space and ventilation?
• Are the terminals suitable for the number of branches?

One large central supply may appear economical, but it can create practical drawbacks:

• More current leaving one unit
• More branches in one terminal area
• Longer cable routes
• Greater voltage-drop pressure
• A larger dark area after one failure
• A larger enclosure
• More difficult cable identification

Several smaller supplies can offer:

• Shorter branches
• Easier left-and-right zoning
• Separate logo control
• Separate front and halo circuits
• Faster fault isolation
• Less sign area affected by one failure
• Better fit in distributed service spaces

However, every extra supply needs:

• AC input
• Mounting space
• Ventilation
• Low-voltage terminals
• Labels
• Wiring
• Testing
• Packing control
• Installation time

The supply count should therefore be optimized, not minimized blindly.

Power supplies should also be assigned according to physical sign zones. A circuit plan that groups alternating letters may balance wattage on paper but create confusing wiring behind the façade. Grouping adjacent letters usually produces shorter and clearer routes.

Compare two plans for a 12-letter sign:

Plan	Circuit arrangement	Installation effect
Plan A	Odd letters on PSU-1, even letters on PSU-2	Cables cross the full sign and are harder to trace
Plan B	Left six letters on PSU-1, right six on PSU-2	Shorter routes and clearer service zones

Plan B is often more practical, provided both loads remain within the approved capacity.

Separate lighting effects need special attention. Front-and-halo-lit letters may use:

• One combined circuit when both effects always operate together
• Two circuits when front and halo lighting switch separately
• Two dimming channels when brightness requires independent adjustment
• Additional controller channels for RGB or RGBW effects

The decision affects cable quantity, connectors, wire exits, supplies and controllers. It should be made before the letter backs and internal wiring are completed.

Each supply should carry a permanent reference matching the documents:

• PSU-1: Letters L01–L05
• PSU-2: Letters L06–L10
• PSU-3: Logo G01
• PSU-4: Halo circuit H01

The same references should appear on the electrical drawing, physical units, cables, test records and packing list.

Where Should Wire Exits Be Placed?

Wire exits should be treated as measured installation interfaces. They are not simply holes placed somewhere behind the letters.

For each letter or logo element, approve:

• Exit direction
• Horizontal position
• Vertical position
• Distance from the outer edge
• Cable length outside the product
• Number of conductors
• Cable identification
• Polarity
• Circuit assignment
• Indoor or outdoor sealing requirement
• Matching position on the installation template

A rear wire exit is common for individually mounted channel letters because the cable passes directly through the façade. Side or bottom exits may be needed for raceway-mounted letters, backer panels, surface conduit or limited wall access.

The exit should align with usable space behind the wall. A hole can be geometrically centered in the letter but still land on:

• A metal stud
• Concrete reinforcement
• A stone bracket
• A curtain-wall mullion
• A window frame
• A fire barrier
• An existing electrical cable
• A water pipe
• A structural beam
• A drainage chamber

Moving an exit 50 mm before production may solve the conflict. Moving it after production may require opening the letter, relocating LED modules, replacing the rear panel, extending the cable and changing the installation template.

A wire-exit schedule should use measured references:

Product ID	Exit direction	Horizontal reference	Vertical reference	Cable length	Circuit
L01	Rear	85 mm from left edge	120 mm from bottom	500 mm	A
L02	Rear	Centerline	110 mm from bottom	500 mm	A
L03	Rear	70 mm from right edge	125 mm from bottom	650 mm	A
G01	Rear, two circuits	See drawing	See drawing	800 mm	B/C

The values are illustrative and should follow the approved product drawings.

Cable length outside the letter also needs attention. A lead that is too short may not reach the hidden branch connection. A lead that is excessively long may be difficult to manage inside a shallow cavity. The required length should come from the wall depth, connection location and installer’s preferred method.

Repeated letters need position-based labeling. A sign reading “COFFEE HOUSE” contains repeated letters, but their wire lengths, stud patterns or circuit groups may differ.

Use labels such as:

• L01-C
• L02-O
• L03-F
• L04-F
• L05-E
• L06-E

Do not rely only on the visible character.

The label should remain understandable after unpacking. A useful system links four items:

Physical item	Matching reference
Letter	L05
Cable	L05-A
Template	L05 position
Circuit drawing	L05 connected to PSU-1

Outdoor wire exits require coordination between factory preparation and site sealing. The factory can prepare the cable, rear-panel exit and product-side protection. The installer must protect the actual building penetration according to the wall system and local conditions.

The installer may need to confirm:

• Sleeve or conduit requirement
• Grommet or bushing
• Exterior sealant
• Cable gland
• Drip loop
• Penetration angle
• Wall waterproofing layer
• Fire-rated sealing
• Corrosion protection
• Strain relief

Wire exits also change when the mounting method changes.

Mounting method	Typical wire approach
Direct mount	Rear wire exits through the façade
Raceway mount	Wires enter the raceway behind the letters
Backer panel	Wires route behind or through the panel
Surface conduit	Side or bottom exits may be required
Glass-area installation	Wires may route through an adjacent frame or opaque panel

Changing from direct mount to raceway mount after production can leave cables in the wrong positions and letter backs prepared for the wrong fixing method. Mounting and wiring should be approved together.

Which Drawings and Responsibilities Must Be Approved?

Production should follow one controlled approval package. Email notes, messaging screenshots and old drawings should not compete with the final production file.

The minimum document package normally includes:

Document	Information required
Overall elevation	Sign size, letter heights, spacing, alignment and logo position
Product section	Face, return, back, depth, LED position and wall relationship
Mounting drawing	Studs, screws, brackets, raceway or backer panel
Wire-exit drawing	Exit coordinates, direction, cable length and labels
Electrical drawing	Input, output, circuits, loads, supplies and controls
Site interface drawing	Wall material, access, penetrations and power location
Installation template	Drilling and positioning pattern
Power-supply layout	Equipment location, spacing and service access
Packing schedule	Letter, supply, cable and accessory identification

The elevation should show more than the overall width. It should include:

• Individual letter heights
• Word spacing
• Baseline
• Logo-to-letter spacing
• Mounting-center references
• Orientation
• Drawing scale
• Final revision number

The product section should show:

• Face material
• Return material
• Letter depth
• Rear panel
• LED position
• Cable exit
• Mounting studs or brackets
• Wall spacing
• Halo-light stand-off distance where applicable
• Drainage or weather-protection details where applicable

The electrical drawing should identify:

• Building input requirement
• LED voltage
• Power-supply model
• Power-supply quantity
• Rated wattage
• Calculated connected load
• Circuit groups
• Cable references
• Polarity
• Dimmers or controllers
• Separate lighting effects
• Supply location
• Maximum planned cable distance

A clear electrical schedule may look like the following:

Circuit	Connected products	DC voltage	Calculated load	Power supply	Control	Position
A	L01–L05	24V	82 W	PSU-1, 120 W	Main switch	Left ceiling zone
B	L06–L10	24V	88 W	PSU-2, 120 W	Main switch	Right ceiling zone
C	G01 logo	24V	54 W	PSU-3, 100 W	Separate switch	Center access panel
D	Halo lighting	24V	71 W	PSU-4, 120 W	Dimmer	Center access panel

The mounting drawing should correspond exactly with the wire-exit drawing. A template cannot be considered approved when its drilling holes belong to a different letter revision.

Version control is essential. The final files should include:

• Project number
• Drawing title
• Revision number
• Revision date
• Changes made
• Approval status
• Approved dimensions
• Approved electrical version
• Approved mounting version

A practical revision record might show:

Revision	Change	Effect
Rev A	Initial direct-mount proposal	Rear exits and individual studs
Rev B	Power supplies moved to ceiling	Cable lengths and circuit grouping updated
Rev C	Halo lighting added	Additional circuits and dimmer required
Rev D	Final approved version	Released for production

Production should use Rev D only. Earlier drawings should be marked superseded so they cannot be mistaken for current files.

For larger projects, sample approval may also be required. Iduoduo supports material samples, color samples, lighting samples, full-size sections, pre-production samples, first-article approval, first-store validation and pilot production. Approved results can be transferred into final drawings, BOMs, process requirements, QC checklists and frozen production versions.

The responsibility split should be written plainly.

Iduoduo can prepare:

• Manufacturability review
• Letter structure
• LED layout
• Low-voltage system
• Power-supply matching
• Circuit grouping
• Internal wiring
• Cable labels
• Wire exits
• Controllers and dimmers
• Raceway or backer-panel preparation
• Mounting templates
• Product testing
• Packing identification
• Electrical and installation records

The local sign company or installer should confirm:

• Final site dimensions
• Wall construction
• Structural support
• Rear access
• Drilling areas
• Equipment access
• Cable routes
• Mounting hardware suitability
• Façade sealing
• Lifting and access equipment
• Property restrictions
• Local installation method

The qualified local electrician should confirm:

• Building AC voltage
• Circuit suitability
• Breaker
• Grounding
• High-voltage wiring
• Junction boxes
• Disconnecting arrangement
• Power-supply mounting
• Final connections
• Local permits
• Inspection
• Final acceptance

Certified power supplies or electrical components do not automatically certify the completed installation. The final sign system includes the building circuit, grounding, mains wiring, enclosure, mounting and site connection.

Before releasing production, run a final approval check:

Final check	Approved?
Destination voltage confirmed	Yes / No
LED voltage confirmed	Yes / No
Power-supply models confirmed	Yes / No
Supply quantities calculated	Yes / No
Loads and reserves recorded	Yes / No
Supply positions measured	Yes / No
Service access confirmed	Yes / No
Cable distances measured	Yes / No
Wire exits dimensioned	Yes / No
Circuits labeled	Yes / No
Mounting method frozen	Yes / No
Wall material confirmed	Yes / No
Template matches final drawing	Yes / No
Controls confirmed	Yes / No
Outdoor sealing responsibilities assigned	Yes / No
AC work assigned to an electrician	Yes / No
Final revision approved	Yes / No

A production release should not contain unresolved notes such as “installer to decide later” for details that affect letter construction. Some site matters must remain with the local installer, but factory-sensitive items—wire exits, cable lengths, circuit groups, mounting preparation and supply specifications—need an approved basis.

Iduoduo carries out a 100% lighting inspection and 72-hour pre-shipment testing for illuminated products, checking LED performance, power-supply stability, wiring, connectors, brightness, color and related electrical functions. Factory testing verifies the manufactured sign package; the local team still needs to verify the building circuit and final installation.

A well-prepared project reaches the site with no mystery cables and no unassigned components. Every letter has an ID, every wire has a circuit, every power supply has a location, every drawing has a revision, and every installation responsibility has an owner.

Plan Your Individually Mounted Channel Letters with Iduoduo

A reliable channel-letter project starts with the information hidden behind the finished façade. Send Iduoduo your logo or vector drawing, required dimensions, installation photos, wall type, mounting height, destination country, available voltage, proposed power-supply position and preferred mounting method. The engineering team can review the letter structure, LED arrangement, electrical grouping, wire exits, mounting pattern and access requirements before production begins.

When some site details are still uncertain, photos, marked-up drawings or a short installation note are usually enough to begin a practical review. Iduoduo can identify the points that still need confirmation and prepare a proposal covering the product structure, power supplies, templates, accessories, packaging and installation interfaces.

Contact Iduoduo with the available project information to request a custom channel-letter quotation. Confirming the electrical and mounting details early helps the completed sign arrive ready for a clearer, faster and more predictable local installation.