Offroad Lighting Wiring

[xcm]

I understand the benefit of moving the switch from a hot to a grounded wire, but how does it cut down on wire used? If you're running the switch to the cab it seems that the same amount of wire is used, whether its switched hot or ground.

On switched hot, you need to run 2 positive wires to your relay. granted one can be from your dash panel hot, but you still need 2 hot wires. With switched ground, you only need 1.
The other benefit, is if you happen to knick a wire, or it comes loose, etc, its much better for this wire to be a ground than a hot, a ground wire wont start a fire, it'll only turn your accessory on.

 

[Breezio69]

Ill take I pic of mine and post it up, its got two relays, one for each set of lights on my roof rack and I wired them superbly.. Haha, but seriously, I'm also not a wire genius and I was surprised how simple it was

 

[jonesinxj]

On switched hot, you need to run 2 positive wires to your relay. granted one can be from your dash panel hot, but you still need 2 hot wires. With switched ground, you only need 1.
The other benefit, is if you happen to knick a wire, or it comes loose, etc, its much better for this wire to be a ground than a hot, a ground wire wont start a fire, it'll only turn your accessory on.

So with a switched ground you will still ground your switch and then just run 1 wire to your relay correct?

 

[magimerlin]

Yes

 

[jeeperjohn]

I understand the benefit of moving the switch from a hot to a grounded wire, but how does it cut down on wire used? If you're running the switch to the cab it seems that the same amount of wire is used, whether its switched hot or ground.

Because instead or running a hot wire from a hot source to the switch to the relay, you only need to run from the battery to the relay and from the relay to the load. You only run one small gage ground wire to the switch.

 

[jonesinxj]

Ok I'm about to change everything over this weekend, can I still daisy chain my common grounds for the switches and then run seperate lines to each ground terminal on my relays?

Sorry for the noob questions

 

[magimerlin]

Yes that would work just fine. As long as each switch has its own ground wire going to the load (outgoing) a common incoming ground to the switch group will be fine.

 

[jonesinxj]

Thank you!!! Just the information I was hoping for!

 

[Forceful Llama]

So on the relay you would run a wire from the 30 to the 86 terminals on the relay?

 

[xcm]

For switched ground, yes. its just a small jumper that patches into the hot feed from the battery, and patches it to 86.

You want +12v on both 30, and 86. 30 Needs to be fed with a thicker wire, because it carries the load of the light or whatever. The patch cable only needs a smaller wire, as it doesnt flow much.

It really helps to make a headlight harness, or just a simple project on the work bench. Once it clicks in your head, it really clicks....

 

[xcm]

This may help visualize why one needs more wiring than the other, on switched ground, you can ground in numerous places, like the dash, or any part of the body. For switched hot, you gotta run a wire from your switch to a 12v source, which is either the fuse block, or back to the engine bay.

It also demonstrates why switching the ground is safer... Your switch wire, wether it hot or ground, has to go thru accross the engine bay, and thru the firewall.

If its a hot wire, it can easily chafe or get nicked and short out. The fuse SHOULD protect in this scenario, but defective fuses are not unheard of, especially if you shop at harbor freight...

If you run a switched ground, and the wire gets chafed and contacts the firewall or other metal parts, your light comes on, and stays on. No big deal, and it even tells you that youve got a short, safely. MUCH SAFER than a shorted out 12v wire.... The less 12v HOT wires or switches inside the cab, the better, especially if you dont run the wires as securely as you should.

Hope the mspaints help.

 

[xcm]

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