No, I think we're in agreement. The two things I was commenting on were something about less power draw (which is why I cited current, since power is consumed mostly at the load and not in the wiring, one would hope), and the consideration for a failure that could cause property damage or physical harm.

Oh, and it isn't necessarily twice the wiring through the firewall. One wire (fused) carrying 12 volts to every switch, plus one wire for each relay coil. Or, you could have two circuits, one for positive-switched circuits, the other for negative-switched. Assuming chassis ground (no wire through firewall), only the one positive wire is added. Right? I'm drawing this in my head, LOL.

"less power draw" I believe he was referring to in the event of a short. But I do agree that some things you don't want to turn on in the event of a short. So consideration of what you are powering makes sense in which side of the control circuit you switch and whether you add a fuse or not to the control circuit.

Exactly. And good points. In fact, if you tap the positive side 12V source from under the dash to power the control circuits there are no additional wires necessary. But you still have the whole short thing to worry about. So I think a good way to do it, based on your observations, would be to switch the positive side of things you don't want to turn on when shorted, but feed that 12V from behind the dash (and make sure you tap a fused feed), and switch the negative side of things that aren't critical. Kind of like designing an intentional failure point into the circuit. Sounds like a win/win to me.

Mark, you are right about some things should not be controlled via the Gnd and gave the perfect example. As said earlier I was speaking of the switches that actuate relays for lights. The current draw from relay coils at 12v is under an Amp and a 24 awg wire will handle that with ease, but if you short the positive side you will surely burn the wire along with the fuse. If the gnd side shorts the device will turn on and the most likely wont blow. Wiring and component rating is a always a balance between worst case and some acceptable risk.

A great diagram, Helped me a lot. Thought I would share. Appreciate you posting it!

Glad you got some use out of it. My time wasn't wasted. And thanks.

Drawing it in your head! lol I love it! I do that all the time! Good to know I'm not the only one Mark :thumbsup::beer:

If you really want to mount the switches above the rearview, you can make a pod yourself if you don't mind working with fiberglass.

When are you going to start selling your work?

I do... sorta... lol

The handmade versions are available but you need to message me.

I'm in the process of having patent work completed as well as molds and production. It just takes time due to the cost... which is fairly high. :eek2: