LED modules are one of the most popular lighting solutions for illuminated signage and light boxes because they are bright, efficient, and easy to install. However, one important rule installers must follow is not exceeding the maximum number of LED modules connected in a single series. Many modules are designed for a maximum of 20 modules per string to prevent voltage drop and uneven brightness.
This guide explains how to correctly wire your LED light box while keeping each string below the 20-module limit.
Why the 20-Module Limit Matters
LED modules typically operate on 12V DC power supplies. When too many modules are connected in a single chain:
- Voltage drops along the cable
- The last modules appear dimmer
- Modules may flicker or fail
- The power supply can be overloaded
To avoid these issues, manufacturers specify a maximum number of modules per series string, often 20 modules.
If you need more modules, simply create multiple strings connected in parallel to the same power supply.
Basic Wiring Concept
The safest way to wire LED modules in a light box is:
- Connect modules in series up to 20 modules
- Start a new string after 20 modules
- Connect each string in parallel to the power supply
This keeps voltage stable and ensures even brightness across the sign.