Aux switch wire gauge

[FKN Slayer]

Do I need to run 10 gauge wire from 5 lights ( 250 total watts ) to the 40 amp aux switch or does the switch already have heavier wire running to the battery? I'm assuming the switch to the battery requires heavier wire. The lights have 14 gauge wire, so I'm trying to determine how heavy a wire I need to tap into and wire to the aux switch.

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[Kevin_D]

You don't have to worry about any wiring from the battery to the switch: it's already wired to provide 40A.
And each lamp will only draw about 4A (based on 5 lights at 250W total,) so you can wire the lights with 14ga. (each light) or 12ga. (for a pair.)
If you want to centralize a terminal strip from the switch to a common point for the lights, a 12ga. would work, but I'd use 10ga. from the Aux. Switch to the terminal block.

Kevin

 

[FKN Slayer]

You don't have to worry about any wiring from the battery to the switch: it's already wired to provide 40A.
And each lamp will only draw about 4A (based on 5 lights at 250W total,) so you can wire the lights with 14ga. (each light) or 12ga. (for a pair.)
If you want to centralize a terminal strip from the switch to a common point for the lights, a 12ga. would work, but I'd use 10ga. from the Aux. Switch to the terminal block.

Kevin

OK, so I should be fine using 12 gauge wire and t taps to connect the lights and run that wire straight to the aux switch wire and tap the ground wire the same way? Obviously, running the ground wire to a proper grounding spot.

 

[ShadowsPapa]

Unless you actually PULL 40 amps, 12 is a lot of wire.
250 watts will be under 20 amps because you'll be running about 13.8 volts unless running with engine off. System voltage is rarely under 13 volts.
Even with engine off and the battery at under 40% (or 12 volts) you'll be pulling only 20 amps. And for what distance? Too few leave out the distance calculation. It depends on distance for the final voltage drop and gauge calculations. I've run heaver loads than that on 14 gauge wire.
A 4 head lamp halogen system from years ago runs on 18 gauge from the switch to the lamps.

 

[FKN Slayer]

Unless you actually PULL 40 amps, 12 is a lot of wire.
250 watts will be under 20 amps because you'll be running about 13.8 volts unless running with engine off. System voltage is rarely under 13 volts.
Even with engine off and the battery at under 40% (or 12 volts) you'll be pulling only 20 amps. And for what distance? Too few leave out the distance calculation. It depends on distance for the final voltage drop and gauge calculations. I've run heaver loads than that on 14 gauge wire.
A 4 head lamp halogen system from years ago runs on 18 gauge from the switch to the lamps.

It should be 16' or under. I am going to route it between the bed and cab and come up from the bottom into the engine compartment. I've been searching forums and have seen guys running as low as 8 gauge to the battery for 2 100 watt lights. So that was giving me a range of 8 to 18 gauge and just adding to my confusion. Thanks for the info.

 

[Hootbro]

FWIW, they use a metric wire gauge system on our Gladiator.

0.75mm would equal a 19 AWG but 18 AWG size would be more standard.

3.0 mm falls in between 12 AWG and 14 AWG. I would always error on the larger 12 AWG.

 

[ShadowsPapa]

FWIW, they use a metric wire gauge system on our Gladiator.

0.75mm would equal a 19 AWG but 18 AWG size would be more standard.

3.0 mm falls in between 12 AWG and 14 AWG. I would always error on the larger 12 AWG.

Park, turn and DRL on these are .75 which I find ironic as it's a lot heaver than was used for standard lamps in the past. Normally they would be 16 gauge at best. 14 was not common in older lighting.
On the other hand, that could explain a few things LOL.

Bigger wire means lower voltage drop over the distance. These are regulated for a reason so I'd never use smaller than factory, even to the point of using larger than factory wiring where there is sensing involved.

The wire provided on the aux switches is also short - there's no distance involved.
After seeing what Oracle used, and the wire used for the lower power aux switches, I used 16 gauge going back to my LED backup lights.

 

[Hootbro]

After seeing what Oracle used, and the wire used for the lower power aux switches, I used 16 gauge going back to my LED backup lights.

Given they are LED's I would be surprise if they draw more than 1 amp per side.

 

[Kevin_D]

It should be 16' or under. I am going to route it between the bed and cab and come up from the bottom into the engine compartment. I've been searching forums and have seen guys running as low as 8 gauge to the battery for 2 100 watt lights. So that was giving me a range of 8 to 18 gauge and just adding to my confusion. Thanks for the info.

Keep in mind that smaller gauge number means a bigger wire.

Kevin

 

[FKN Slayer]

Keep in mind that smaller gauge number means a bigger wire.

Kevin

Yeah, that's why I thought 8 gauge was a little ridiculous for 200 watts of lights.

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