Wiring question: Where to tap into the ignition?

[smitty]

Hiya,

I need to tap into 12v ignition from somewhere, but I dont want to splice onto any old ignition wire...

Here's why:

Ive made up some bus bars/distribution blocks/whatever you want to call them (how-to coming soon!) for easy electrical accessory installation, but as it could potentially be running up to six different things, I want to make sure that the existing ignition wire can handle all the power.

Where's the best spot for me to tap into? Or will any old wire be good enough?

Ground is already done so this is the only thing holding me up.

And yes, i've already made provision for an in-line fuse, 10amp, for safety.

 

[Macca]

10 amp isn't too much current draw you could use the igniting wire from the back of the igniting barrel.

Alternatively you could run a power wire from your battery into the car to a relay (terminal 30) and from the relay (terminal 87) to your distribution block then use a wire spliced from the ignition wire mentioned earlier as the switching wire on the relay(terminal 85), and earth the other side of the switching circuit of the relay(terminal 86) to your car body.

 

[unclepaulie]

radio power or cig lighter power?

 

[Macca]

Nah, both of those are accessories not ignition, you may be able to find an ignition feed at the back of the radio but why worry about that when the back of your ignition switch is easier to get to?

 

[smitty]

Will the radio or cig be able to handle up to six things running from it?

 

[sanchez]

Mate it's not the radio or cig you have to worry about, it'll be the wiring feeding these circuits. What you'll have to work out is what you want to hang off your'distribution point as the effective circuit will be paralleled from your originating source wire ( from ignition switch) and as such this wire will need to be able to cope with all distributed circuits. I also imagine you will be providing a fused circuit from your distribution point as well. Just a thought.

 

[Macca]

You would be far better off running a new wire and using a relay like I said above, here is a picture of how to do the wiring:

 

[naughtika]

I'd go with Macca's suggestion..

do it once, do it right.. and safe!

 

[smitty]

That's sort of what I was getting at: what wiring can handle the additional load. All this distribution block will be for is an easy point to wire ebc/gauges from, rather than splicing wires every time I install something I can just plug it into one of the terminals.

Mate it's not the radio or cig you have to worry about, it'll be the wiring feeding these circuits. What you'll have to work out is what you want to hang off your'distribution point as the effective circuit will be paralleled from your originating source wire ( from ignition switch) and as such this wire will need to be able to cope with all distributed circuits. I also imagine you will be providing a fused circuit from your distribution point as well. Just a thought.