This is such a basic electrical question, I'm almost embarrassed to ask, but haven't found a clear answer...

I'm going to install Hella Black Magics. I'm using 10 AWG stranded copper. That is admittedly overkill. This WON'T be wired into the OEM harness, but will be on demand from a separate switch with separate wiring. So the question....

Can I "share" the power lead that will be feeding the relay (feeding #30) with the power lead that will be feeding the switch in the car? In other words, what I had planned on doing is running TWO power wires....one to the relay and one to the switch. (The switch will then have a trigger wire that runs to the relay to engage power to the lights by 'throwing' the relay open). Both would have inline fuses (15 for the relay power, 2 for the switch power).

That approach seems needlessly complex. I'd think given the size of the wire I'm using, there will basically be no issue with resistance or surge. The stock wire that Hella provides looks woefully small to me. Maybe 18 AWG. But I don't know if I'm missing something about how this works.

Anyhow, easy enough to run two power wires, separately fused, but seems silly. Can anyone with experience advise? Thanks in advance. John

 

Yes.
The switch is only closing a low a relay coil.
Added an electric fan to the boys truck for A/C. Did exactly that.

 

Awesome. Thanks so much!

 

concur

you CAN do that.
the purpose of the relay is to keep the full AMP load the lamps pull, away from the switch allowing use of a lower AMP feed but since the 'control' side of the relay won't pull much juice the higher feed won't hurt anything.

I've wired extra lights and air horns this way