Installing a 30 amp relay by Richard Cook
	After all the talk on CJU about failing ignition switches I thought I’d make my odds a bit better by cutting the load running through mine by about half. I picked up a 30 amp relay designed for a heavy duty lighting system. This is a pretty compact unit but a bit more complex than some relays. You can get relays with three wires as ground is through the case. In all cases you are going to have two large wires for the switched load. You want these to run from your battery terminal to the load itself, in this case the ignition side of the wiring harness. This keeps the load for this system out of your switch requiring only a low amp load to control the relay. In this case we have a control wire from the switch to turn on the relay and we need a ground wire for this circuit. What happens in a relay is that a low current circuit initiates a magnet that pulls the two heavy duty contacts together. This particular relay has a ground terminal, a terminal to the ignition switch to complete the magnetic circuit, a wire from the battery, (in this case this is the red wire from my circuit breaker), and this one has two terminals for the heavy load to connect to. Most relays come with simple directions indicating terminal numbers for each function. The first picture shows the relay I bought at Kragen auto parts. I’ve seen this unit at several stores. I mounted and grounded the relay on the speedometer mounting screw. You will need a number of spade terminals; I ran out and had to reuse some from old test wires. The second picture shows the relay out of the box next to the ground wire I have just made. The ground wire is only for the control circuit so 14-16 gage wire is fine. I then made up a red heavy 10 gage for the main power from the circuit breaker to the relay operating circuit. I used another little 14-16 gage wire for the control circuit from ignition switch to relay. The wire that went to the ignition switch from the hot while on European style connector block just needed to be removed from the switch and plugged in to the load output side of the relay. The third picture shows the relay mounted and the control wire to the switch as well as a clear shot of the heavy duty wire from the breaker. The last picture fades back a bit so you can see the power wires attaching to the circuit breaker which is that box on the right.