A channel letter quote usually contains a line that reads something like “aluminum returns, acrylic faces, trim cap, white LEDs, remote power supplies.” If you have not bought an illuminated sign before, that tells you very little. This glossary walks through each part of a channel letter, from the wall outward, so you can read a quote, compare two of them, and know what you are paying for.
The Letter Body
Back
The back is the flat panel in the shape of the letter that sits against the wall or raceway. On a standard front-lit letter it is aluminum, and the LED modules are fixed to it. On a halo-lit letter the back is clear plastic, usually polycarbonate, so light can pass through to the wall.
Return
The return is the side wall of the letter. It is a strip of aluminum bent to follow the letter’s outline and joined to the back, and its width is the letter’s depth. Returns are painted, most often black, white, bronze, or a color matched to the brand or the building. Because you see the returns from every angle except straight on, their color has more effect on the daytime look than most buyers expect.
Depth
Depth is how far the letter stands off its back. Five inches is the common standard for front-lit letters. Shallower letters look sleeker but leave less room for the light to spread evenly across the face, so depth and LED layout are designed together.
Weep Holes
Weep holes are small drain holes at the lowest point of each letter. Outdoor letters are never perfectly sealed, and the holes let rain and condensation out before it reaches the electrical parts. Blocked weep holes are a common cause of early failures.
The Front of the Letter
Face
The face is the front of the letter. On a front-lit letter it is translucent acrylic that diffuses the LED light into an even glow. The color can come from the acrylic itself or from translucent vinyl applied to a white face, which is how exact brand colors, gradients, and printed graphics are achieved. One useful variant is day/night film: the face looks black in daylight and lights up white at night.
On a halo-lit letter the face is solid metal and no light passes through it. The difference between the two styles is covered in front-lit vs. halo-lit channel letters.
Trim Cap
Trim cap is the plastic edging that wraps the perimeter of the face and attaches it to the return. It holds the face on, covers the joint, and gives the letter a thin outline. It comes in a range of colors and a couple of widths. Trimless letters, in which the face sits flush with no visible edging, are also available for a more modern look at a higher price.
The Lighting System
LED Modules
Modules are the small light units inside the letter, each holding a few LEDs, wired together in a chain. They run on low voltage and come in white at several color temperatures as well as red, blue, green, and color-changing versions. Two things separate a good lighting job from a poor one: the quality of the modules and how many are used. Too few, spaced too far apart, produces visible hot spots and dark areas on the face.
Power Supply
LED modules do not run on wall current. A power supply, sometimes called a driver, converts the building’s line voltage to the low voltage the LEDs use. A sign usually has several, each feeding a few letters. They are placed inside the raceway, or behind the wall in a flush-mounted installation. Power supplies tend to wear out before the LEDs do, so where they are located determines how easy the sign is to service.
Wiring and Pass-Throughs
Each letter has a low-voltage lead that runs back to its power supply. On a flush-mounted sign that lead passes through the wall in a sealed sleeve. On a raceway sign it passes straight into the raceway.
Disconnect Switch
An electric sign needs a means of shutting off its power for service. The switch is often on the raceway or near the sign. If your sign has a small toggle on the end of the raceway, that is what it is for.
Photocell or Timer
A photocell switches the sign on at dusk and off at dawn. A timer does the same on a schedule. Either one saves energy and extends the life of the lighting.
Mounting Hardware
- Studs and pattern. Flush-mounted letters are held by threaded studs. Installers work from a full-size paper pattern taped to the wall that marks every hole.
- Standoffs. Spacers that hold halo-lit letters a set distance off the wall.
- Raceway. The aluminum box that carries letters, wiring, and power supplies when letters are not mounted directly to the wall.
- Backer panel. A flat panel behind the letters that hides wiring and provides a clean background.
For how to choose among these, see raceway vs. flush mount channel letters.
The UL Label
Electric signs are built to a safety standard, UL 48, and a sign built to it by a listed shop carries a UL label. Electrical codes call for electric signs to be listed and labeled, and inspectors and landlords look for it. Ask whether the sign will be UL listed before you order, not after it is on the wall.
Why the Parts Matter When You Compare Quotes
Two quotes for “the same sign” can differ by a wide margin because the parts differ. Before comparing prices, check:
- Letter depth, and the material of the backs and returns
- Face material, and whether the color is in the acrylic or applied as vinyl
- LED brand, color, and warranty
- Number and location of power supplies
- Mounting method, and whether a raceway or backer is included
- Whether the sign is UL listed
- Whether permits and installation are included
Our guide to channel letter cost in NYC explains how each of these moves the price.
Frequently Asked Questions
What are channel letters made of? Aluminum backs and returns, acrylic faces, plastic trim cap, and LED lighting. Halo-lit letters use metal faces and clear backs.
What is the standard depth of a channel letter? Five inches is the industry standard for front-lit letters. Signs NYC fabricates depths from 2 to 12 inches.
Can the faces be replaced without replacing the sign? Yes. Faces and trim cap can be remade and swapped onto the existing letters, which is a common refresh after a rebrand or years of sun.
What usually fails first? Power supplies, followed by individual LED modules. Both can be replaced. See channel letter repair and maintenance.
Have a Quote You Want Explained?
Send it over. Signs NYC will walk you through what each line means and where the differences are. Request a quote or call 718-453-8300, and see finished examples on our channel letters page.
