In conventional relay wiring, 30 is the main battery service power to what you want to activate, 87 is the relay output terminal to the item being serviced. (in this case, the starter solinoid)

86 is the 'trigger' source (key switch, toggle, what have you, as long as it itself has power to feed down the wire to the relay) and 85 is the ground for the relays internal solinoid circut.

As listed above, both layouts should work fine as the only difference is the inversion of wires from trigger to relay internal solinoid ground. (loosely put, 86 and 85 are the light switch that turn on the 30 to 87 circut)

 

Thanks for the reply Darren.

 

If I can piggyback a question without too severely hijacking the thread, what amp capacity relay is required? I see them cheap all over eBay, but don't know if, say a 30A relay is sufficient.

 

@ Spike: No prob.

If you're actually going to put in a starter relay and this is part of the research, make sure you remember to disconnect the battery as it can get real ugly real quick in that confined area when the main battery cable manages to find its way to ground.

@ Farace:

30 amp is quite adiquate. If you fuse it, go for at least a 20amp fuse, but not any higher than 30amp on a 30amp relay as you want to fuse to pop before the relay melts down.


EDIT: It may not be a wise choice on my part, but for the starter relay I do not use a fuse in the circut. I'm not suggesting or condoning it, but letting it be known that is one circut I literally did not want to fuse as I felt the initial voltage surge on such a high draw circut would be having me change fuses all the time just to start the car. Not saying it's right, just what I've done. All my other self installed relay circuts are indeed fused though.

 

I've added both wiring methods above to the FAQ for ease of future reference.

 

Tifosi- Where is this FAQ youre talking about?

Thanks

 

On the Spider main page.