Quick answer
Measure the letter, select a module that suits its depth and stroke, dry-fit the layout, wire to the manufacturer’s diagram, calculate the power supply from the connected load, and test with the actual face before closing the letter. Spacing must be proven by the illuminated result — not copied blindly from another job.
Before starting: specification and safety
Confirm the module voltage, output, colour temperature, IP rating, maximum modules per run and fixing instructions. Match the power supply output voltage exactly. Keep the mains and low-voltage sides clearly identified throughout fabrication.
Electrical safety
Isolate electrical supplies before inspection or connection. Mains-side installation, earthing, protection and final connection must be completed by a competent person in accordance with applicable requirements. Refer to HSE electrical safety guidance.
Nine professional installation steps
- 1
Record the letter geometry
Measure return depth, stroke width and the space around clips, studs, joins and cable entries. Mark areas where a module body or lens cannot sit flat. Photograph complex letters before starting.
- 2
Prepare the mounting surface
Remove dust, swarf, grease and release residue. The surface must be clean, dry and compatible with the module fixing method. Follow the module manufacturer’s preparation and fixing instructions.
- 3
Dry-fit the layout
Place modules without committing to the final fixing. Begin with the narrow strokes and tight curves, then work into the broader sections. Keep the optical pattern consistent and avoid sharp cable bends.
- 4
Fix modules in a repeatable pattern
Maintain consistent orientation and spacing. Do not force a nominal grid through a curve if it creates dark edges; the illuminated face is the performance target, not perfect-looking rows inside the letter.
- 5
Complete the low-voltage wiring
Maintain positive and negative polarity throughout. Use cable and connectors suitable for the current and environment, protect conductors from sharp metal edges and follow the module supplier’s maximum-run guidance.
- 6
Calculate and position the power supply
Multiply module quantity by watts per module, then select a compatible constant-voltage power supply with suitable capacity. Position it so it remains ventilated, protected and accessible for inspection or replacement.
- 7
Test electrically before fitting the face
With the supply isolated, inspect polarity, terminations and cable restraint. Then energise safely and confirm that every module operates correctly and the measured low-voltage supply is appropriate.
- 8
Inspect face uniformity
Fit or temporarily hold the production face in place. View from normal distance in controlled light and check for hotspots, dark corners, edge shadow and colour mismatch. Adjust the layout before final closure.
- 9
Document the completed installation
Record the module model, colour temperature, quantity, power-supply model, layout photographs and test result. Good records make later extensions and service work faster and more accurate.
Module spacing and hotspot control
Module spacing is a system result. Return depth, lens angle, lumen output, face opacity, internal surface and stroke width all affect the distance at which individual light sources blend into an even face.
Start with the supplier guidance, but test the shallowest, narrowest and widest parts of the job. Corners and stroke ends often need attention because light cannot arrive from beyond the edge. Adding modules everywhere can increase heat and power without correcting poor geometry; repositioning can be more effective.
Use the same face material in the test. A layout that looks even through one acrylic can show hotspots or appear dim through another.
Related: How to choose the right LED module for channel letters.
Wiring, polarity and power-supply planning
Maintain polarity
Mark positive and negative conductors consistently. Reversed connections can stop a string from operating and complicate fault finding.
Respect run limits
Do not extend a module chain beyond the manufacturer’s stated maximum. Divide the load into suitable branches.
Protect cable routes
Use protected entries and prevent insulation from bearing against sharp letter returns, screws or moving panels.
Keep access
Place the power supply and junctions where they can be inspected, tested and replaced without dismantling the complete sign.
For the load calculation and design headroom, use the LED sign power-supply sizing guide.
Final quality-control test
| Check | Pass condition | If it fails |
|---|---|---|
| All modules operate | No dead or intermittent modules | Isolate and inspect polarity, connection and local damage |
| Face uniformity | No unacceptable hotspots, shadows or dark ends | Reposition modules or revise spacing in the affected geometry |
| Colour consistency | No visible colour shift between sections | Check variant, production batch and replacement module |
| Supply condition | Correct output voltage and normal operation | Recheck load, cable run and power-supply specification |
| Serviceability | Supply and key connections remain accessible | Revise mounting before the sign is installed |
Glowfy K2 PRO and K8 PRO installation options
Both modules use Philips 2835 LED chips, operate at 12V DC and have a 170° beam angle, IP68 construction, CE and RoHS documentation and a five-year warranty. Their different output levels give the fabricator two specification points to test against the letter geometry.
Compare these specifications with other selection criteria in the professional LED module comparison guide.
GL K2 PRO
0.72W and 70 lm per module. Test it where controlled output and compact layouts are priorities.
View current K2 PRO specificationGL K8 PRO
1.2W and 120 lm per module. Test it where higher useful output is required.
View current K8 PRO specificationAlways confirm the selected colour-temperature variant and current product instructions before installation.
Common installation mistakes
Copying spacing from another product without testing the optics and output.
Final-fixing every module before viewing the production face.
Mixing colour temperatures or batches within the same illuminated sign.
Exceeding the supplier’s maximum modules per run.
Sizing the power supply from guesswork rather than the connected wattage.
Leaving cable against sharp metal edges or without suitable restraint.
Making the power supply inaccessible after installation.
Treating an IP-rated module as a substitute for good drainage and enclosure design.
Frequently asked questions
How far apart should LED modules be in channel letters?
There is no universal spacing. It depends on the module optics, output, letter depth, stroke width and face material. Start with the product guidance, then prove the layout in a representative test letter.
Should channel-letter LED modules be wired in series or parallel?
Most 12V constant-voltage sign modules are supplied in strings and connected to the power supply according to the manufacturer’s parallel wiring diagram. Maintain polarity and never exceed the stated maximum modules per run.
How much spare capacity should an LED power supply have?
Calculate the total connected module wattage and follow the power-supply manufacturer’s loading guidance. A common design approach is to avoid operating continuously at maximum rated load; Glowfy’s sizing guide explains the calculation.
Can I install LED modules before testing the sign face?
Dry-fitting and illuminating a sample before final fixing is strongly recommended. The face material, return depth and internal finish can change the visible result even when the module specification is unchanged.
What should I check before closing a channel letter?
Confirm polarity, supply voltage, secure connections, operation of every module, cable restraint, power-supply access and even face illumination. Photograph and record the final layout for future service work.
Build the test letter before the production run
Browse Glowfy LED modules or speak with the Birmingham team for product guidance backed by 15 years of signage experience.