Relay questions

[Urch]

Can someone explain in detail why we need relays to operate aftermarket lights.

 

[TMyers]

Some aftermarket lights use a lot of power or several amps. A switch and wiring would have to be heavy duty to carry this extra amp load. The relay acts as a "Go Between" where as the light duty switch and wiring only have to power the relay. Then, the relay powers on the lights using a heavier gauge wire supporting the required amp load.

 

[CincyCuda68]

Some aftermarket lights use a lot of power or several amps. A switch and wiring would have to be heavy duty to carry this extra amp load. The relay acts as a "Go Between" where as the light duty switch and wiring only have to power the relay. Then, the relay powers on the lights using a heavier gauge wire supporting the required amp load.

Well said!

 

[muddy12]

Also, with a relay, you have the option to “ground trigger” the relay. Then you don’t have to. Worry about running “constant hot” wires into the cab.


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[Dennis Gulau]

Technically, you don't need to use a relay, but if you don't, you need to use a switch and wires that will reliably carry the amps needed for the lights.