If you’re planning to use a light bar, you may want to invest in a relay harness. Light bars, of course, are commonly found on ATVs, trucks, tractors, utility vehicles, emergency vehicles and construction equipment. Consisting of a long bar-like fixture, they feature a row of light-emitting bulbs or diodes. Rather than connecting the light bar directly to the vehicle’s battery, however, you can connect it to relay harness.
Overview of Relay Harnesses
Relay harnesses are wiring kits that connect a light bar to the vehicle’s battery. They typically consist of a relay (switch), fuse, wiring and connectors.
You can always build a custom wiring setup for a light bar, but a relay harness offers a simpler solution. Because they feature everything you need to connect a light bar, they promote faster and easier installation. But that’s not the only benefit of using a relay harness.
How the Relay Works
Among the most important components in a relay harness is the relay. The relay works like a switch to control a high-current circuit. When you activate the relay inside the vehicle, a small amount of electricity will travel to the relay. The relay will then close its contacts, at which point electricity will travel from the battery to the light bar via separate, heavy-gauge wiring.
The relay essentially reduces unnecessary wear and tear on components. Light bars, particularly high-wattage light bars, draw a lot of electricity. Running them directly through the dash to the battery can cause them to melt. The relay in a relay harness uses heavy-gauge wiring to prevent damage such as this.
In addition to protecting components from damage, the relay allows for better lighting performance. Voltage drops can occur when running light bars directly to the battery. The relay prevents voltage drops, allowing for maximum brightness and performance.
How the Fuse Works
Another important component in a relay harness is the fuse. It acts as a safeguard against overcurrent and short circuit events.
Most relay harnesses for light bars have an in-line fuse. If an overcurrent or short circuit event occurs, it will interrupt the flow of electricity. A thin conductor within the fuse will break or melt, at which point electricity will no longer be able to travel through the fuse. Without electricity, the wiring and other electrical components will be protected from damage.
In Conclusion
Relay harnesses are more than just accessories; they protect light bars from damage while simultaneously allowing for maximum brightness. The relay acts as a switch to reduce unnecessary wear and tear and components, whereas the fuse acts as a sacrificial device to protect against short circuit and overcurrent events.