Switched 12v Power question

[Rian_Colorado]

Hello all!

So it appears to me that switched 12v power for the Ron Francis wiring harness setup runs through the keyed ignition switch. (orange and dark grey wires coming off the ignition switch) In my mind, that means that 100% of all load on the ACC must transit through the ignition switch. Des anyone know what the amp load limit is with that switch? (In other words, what's the sum acc amp limit of a typical Coupe?). I'll be running a heater etc....
The reason I ask is that I've swapped the keyed ignition for a toggle switch, and I want to make sure I don't overload the switch. I'm fine adding a relay or 2, but I would need to know the amp ratings for the relay{s} too.....

Always a learning opportunity with this project!
Rian

[TTimmy]

I believe my coupe came with a 30 amp ignition switch. You are correct that the accessory runs through that switch.

If you are concerned about the capacity of your toggle you could easily introduce relay in order to offload the current from your toggle switch as you suggest. High quality 40 and 80 amp relays are pretty reasonably priced and offer cheap insurance!

[edwardb]

Actually, both ACC (BRN-ACC-FEED) and IGN (ORG-IGN-FEED) switched power go through the ignition switch. +12V for each is from the the BAT (RED-IGN SW -> SOL) connection. I can't tell you how much current actually goes through each or what the switch is rated at. 30 amps for each is probably a reasonable estimate. But a conservative approach would be to add up the ratings of the fused circuits powered by each in the fuse panel. That would mean 40 amps for the ACC circuits and 50 amps for the IGN circuits.

[Rian_Colorado]

Thanks guys! -

Paul that's kind of my question/concern as well. With both elements of switched power flowing through the ignition switch, that means that it's possible that you could have like 90amps going through the ignition switch the way RF and FF have it set up? I can't imagine that the included ignition switch is rated for anything near that (though I haven't been able to find any documentation on the switch/specs). Even 1 40a relay would be beyond the capacity of the switch.....

RR

[edwardb]

Thanks guys! -

Paul that's kind of my question/concern as well. With both elements of switched power flowing through the ignition switch, that means that it's possible that you could have like 90amps going through the ignition switch the way RF and FF have it set up? I can't imagine that the included ignition switch is rated for anything near that (though I haven't been able to find any documentation on the switch/specs). Even 1 40a relay would be beyond the capacity of the switch.....

RR

Given the fact that ACC and IGN are switched ON/OFF separately in various positions of the switch, I think it's fair to guess they're separate connections inside the switch. That would mean the max fuse panel of 40 and 50 amps are flowing through separate paths. I don't think the current draw is additive.

[GT_Rich]

I just encountered all this about two months ago. I am building this as a race car. I wanted a push button start and a toggle switch to power everything. My solution is explained in the YouTube link below. From RFW, both ACC and IGN circuits are fed to the fuse panel with 10 gauge wire from the ignition switch. 10 gauge is generally accepted to be 30 amp limited. Furthermore, the ignition switch is supplied power for these circuits with a single 8 gauge wire. 8 gauge is going to typically be 50 amp max, so the sum of these two circuits should be limited to that.

Of course, there are no fuses on these runs and you'll draw what you draw up to the combined fuse limit in the panel. With my approach, everything is on switched relays, each feed is separately fused, and everything is contained in one tidy, sealed box.

https://youtu.be/_OmAz4ZyQgc

[Rian_Colorado]

After chewing on this for a few hours, I went with adding 2 40a relays (one for each circuit). Like Rich, I wanted a toggle and push button. Rich's solution is very elegant for sure, but I don't have room under that panel with the vintage AC system! Don't think my wiring will be QUITE as pretty as that....lol. Another few days and I SHOULD have the in cabin wiring done (hopes and dreams!)

Rian

[Windsorpower]

I just encountered all this about two months ago. I am building this as a race car. I wanted a push button start and a toggle switch to power everything. My solution is explained in the YouTube link below. From RFW, both ACC and IGN circuits are fed to the fuse panel with 10 gauge wire from the ignition switch. 10 gauge is generally accepted to be 30 amp limited. Furthermore, the ignition switch is supplied power for these circuits with a single 8 gauge wire. 8 gauge is going to typically be 50 amp max, so the sum of these two circuits should be limited to that.

Of course, there are no fuses on these runs and you'll draw what you draw up to the combined fuse limit in the panel. With my approach, everything is on switched relays, each feed is separately fused, and everything is contained in one tidy, sealed box.

https://youtu.be/_OmAz4ZyQgc

Digging up an older post hoping for some clarification. Rich, I’d like to use that Eaton box to get rid of the clunky ignition switch in a roadster I’m building. In your video, you mention feeding the relay box with a 4 gauge wire direct from the battery. What happens to the 8 gauge red wire that normally carries power to the ignition switch?

[Windsorpower]

Digging up an older post hoping for some clarification. Rich, I’d like to use that Eaton box to get rid of the clunky ignition switch in a roadster I’m building. In your video, you mention feeding the relay box with a 4 gauge wire direct from the battery. What happens to the 8 gauge red wire that normally carries power to the ignition switch?

Longacre racing makes toggle switches rated for 40 amps. I’m thinking of using these to ditch the ugly starter switch.