12V LED Sign Power Supply, Outdoor IP67, UL Listed, 60 to 150 W

This is the part that turns the 120 V line power of a building into the 12 V DC that LED channel letters and signs run on. It is a constant-voltage LED driver in a sealed metal case rated IP67: dust-tight, and protected against water even if it is briefly submerged. The supply is UL listed. Sign makers also call it an LED driver, a sign power supply or, loosely, a sign transformer.

Choose 60 W, 100 W or 150 W. At 12 V that is 5 A, about 8.3 A and 12.5 A of output.

Size it so the LEDs use no more than about 80 percent of the rating. A supply that runs below its limit stays cooler and lasts longer. In practice:

• Up to 48 W of LEDs: 60 W supply.
• Up to 80 W of LEDs: 100 W supply.
• Up to 120 W of LEDs: 150 W supply.
• More than that: split the sign across two or more supplies.

To find the LED load, read the label on the old power supply, or count the LED modules and multiply by the watts per module.

The input is 100 to 130 V AC and is hard-wired, so a licensed electrician connects it. It does not run on 277 V circuits. The 12 V output goes to the sign's positive and negative leads; low-voltage wire from the power supply to the letters is sold separately.

Mount the supply where it stays dry and you can reach it later: inside a raceway, behind the wall or in a weatherproof box. Even with an IP67 case, a spot out of standing water makes service easier and keeps connections dry.

Connect the letters in parallel: each letter's positive lead to the positive output and each negative lead to the negative. Keep the 12 V runs as short as you can. On long runs the far letters can look dimmer, so use heavier wire or a second supply closer to them.

It replaces most 12 V channel letter power supplies. Before you order, check the label on your old unit: it should say 12 V DC output. If it says 24 V, or if your sign is glass neon with a high-voltage neon transformer, this supply is not the right replacement. Send us a photo of the label if you are not sure.

Start with the label on the supply you are replacing. Note the output volts and the watts (or amps; amps times 12 gives watts at 12 V). The output must say 12 V DC.

If you are powering new LEDs, add up their watts: modules times watts per module. Divide by 0.8 and pick the next size up. Example: 70 W of LEDs divided by 0.8 is about 88 W, so choose the 100 W supply. Anything over 120 W of LEDs goes on two supplies.

Then decide where it will live: inside the raceway, behind the wall or in a weatherproof box near the sign, with room for the electrician to work. Add enough 18 AWG low-voltage wire to reach the letters if the old wire will not be reused.