How to add 30 amps worth of switched 12V power?

[CorvallisBMW]

As part of my turbo setup I'm in need of extra power for the gauges, gauge lights, intercooler fan, and intercooler sprayer. The IC stuff technically doesn't need to be switched 12V, but the gauges do. Rather than adding 4 separate circuits with 4 in-line fuses, I purchased a small distribution block and 6-circuit fuse block. This way I can keep all my new circuits/fuses in 1 place (probably in the glove box area) and simplify some wiring. My question is, what's the best way to feed this distribution block with roughly 30A worth of switched 12V power? Is there a good source for that much amperage already, or should I consider pulling straight off the factory distribution block on the firewall (where the battery cable comes in) and putting in a relay to make it "switched"? Thanks for the help!

[Gregs///M]

I suggest you pull your new power from the distribution block on the firewall using a minimum of 4AWG cable. Alternatively, you may take it directly from the battery which is the best place but more difficult.

For your switched sources, you will have to use relays for any HEAVY electrical load systems.

Don't forget to add a fuse coming from the dist block or battery.

Good luck

[golde30]

30A for gauges? pretty overkil, but definately want to pull power from dist block and just give it a relay switched 12v signal to power it on and off. Car stereo circuits in most cars run off shared circuit with many other lights and whatnot and only have 10A. 4AWG as mentioned above would be rite for real 30A draw, but in reality you wont be pulling that much power, so 10AWG is going to be more than enough.

[CorvallisBMW]

I say 30A because that's the total power going through fuse block, so the feed needs to be able to hand that much.

My thought is to do it like this: firewall distribution block -> 30A fuse -> relay -> distribute in to fuse block -> fuse block -> separate out in to 4 circuits for various needs

[golde30]

The fuse block will not draw 30A all by itself, that's just the max rating before it melts. But yah your method seems sound to me.

[barbierij]

How about a starter solenoid / relay for a garden tractor? or one of these http://www.hifisoundconnection.com/S...3CvxoCQVHw_wcB