Off road light wiring
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Senior Member
Joined: Apr 2014
Posts: 366
Likes: 13
Off road light wiring
Hey guys and gals. Here's what I got:
-Custom built bumper light bar with 4 tabs for lights
-4 100 watt halogen 6 1/4" lamps
-25' of 10 gauge wire
-20' of 14 gauge wire
-1 30 amp rocker switch
-2 30 amp relays
-3 inline fuses
-All wire connectors, quick disconnects, and quick splices I can ever need
10 gauge is used between lights, relays and battery.
14 gauge will be used between switch and relays, the ground of switch, and the 12v power to switch.
Couple of issues and questions have arisen:
1) I am running 4 lights at 100 watts a piece to equal 400 watts. 30 amp switch is rated at 360 watts, but since I am using relays to separate it all out and to take the load off of the switch, I will be ok running both relays to just that one switch correct?
2) 100 watts / 12v = 8.33 amps per light. Therefore roughly 16.66 amps per relay, so running a 20 amp fuse between relay and battery per relay will be about the right size fuse correct?
3) Coming off of the switch, I know where I'm grounding it, and I know how I'm getting it to relay, but where is the best place to draw the +12v power to the switch from? Can I run a fused line directly from the battery? Or do I splice into hot cigarette lighter wire? Or is there a better wire to splice into?
4) Where have you guys put the switches? Looking for best possible place.
Thanks for reading and any help is greatly appreciate. I want all ideas, criticism, and changes.
Some pics, including my rough sketch of my wiring.
-Custom built bumper light bar with 4 tabs for lights
-4 100 watt halogen 6 1/4" lamps
-25' of 10 gauge wire
-20' of 14 gauge wire
-1 30 amp rocker switch
-2 30 amp relays
-3 inline fuses
-All wire connectors, quick disconnects, and quick splices I can ever need
10 gauge is used between lights, relays and battery.
14 gauge will be used between switch and relays, the ground of switch, and the 12v power to switch.
Couple of issues and questions have arisen:
1) I am running 4 lights at 100 watts a piece to equal 400 watts. 30 amp switch is rated at 360 watts, but since I am using relays to separate it all out and to take the load off of the switch, I will be ok running both relays to just that one switch correct?
2) 100 watts / 12v = 8.33 amps per light. Therefore roughly 16.66 amps per relay, so running a 20 amp fuse between relay and battery per relay will be about the right size fuse correct?
3) Coming off of the switch, I know where I'm grounding it, and I know how I'm getting it to relay, but where is the best place to draw the +12v power to the switch from? Can I run a fused line directly from the battery? Or do I splice into hot cigarette lighter wire? Or is there a better wire to splice into?
4) Where have you guys put the switches? Looking for best possible place.
Thanks for reading and any help is greatly appreciate. I want all ideas, criticism, and changes.
Some pics, including my rough sketch of my wiring.
Oklahoma
Joined: Dec 2010
Posts: 212
Likes: 5
From: Oklahoma
I did this on my truck. Yes I wired it straight from the switch to the battery, with a fuse of course by the battery. Grounded the lights at the brush guard. I didn't need to use any relays though, but I only had two. How I did it was run the wire under the hood along the wheel well, take it through the hole where the other wiring goes into the cab. I drilled a switch on the plastic under the steering wheel. i can upload a picture if needed. Grounded the switch there if yours lights up when on. Then took the wire from the switch back through that hole, to engine bay along the top and straight to the battery with a fuse. As long as you have the correct gauge wire and fuses, you should be good to go straight to battery, I always have.
Thread Starter
Senior Member
Joined: Apr 2014
Posts: 366
Likes: 13
I did this on my truck. Yes I wired it straight from the switch to the battery, with a fuse of course by the battery. Grounded the lights at the brush guard. I didn't need to use any relays though, but I only had two. How I did it was run the wire under the hood along the wheel well, take it through the hole where the other wiring goes into the cab. I drilled a switch on the plastic under the steering wheel. i can upload a picture if needed. Grounded the switch there if yours lights up when on. Then took the wire from the switch back through that hole, to engine bay along the top and straight to the battery with a fuse. As long as you have the correct gauge wire and fuses, you should be good to go straight to battery, I always have.
Anyone else?
Last edited by Bossgame; Aug 5, 2014 at 11:33 PM.
Thread Starter
Senior Member
Joined: Apr 2014
Posts: 366
Likes: 13
Well got it all done. Thanks to redeye for the reply. I did wire the +12v straight from the wire with an inline fuse. Came out perfect and to my surprise, worked great with the first flip of the switch. Got all good grounds, and hoping I put the relays in a spot that won't get wet when it rains, but I guess well see. They are on top of the washer fluid reservoir, stuck on with 3m double side tape. Zip tied in case the 3m tape fails.
Lights = $40
Light bar = $100
Wire, connectors, switch, relays, and fuses = $30
Pretty happy about $170 total cost, and the knowledge I gained doing it all.
Took me about 4 hours.
I love where I mounted the switch and how factory it looks. Lights are very bright, easily adjustable, and good quality.
I know a lot of you were interested in this (sarcasm), but if anyone is here's some pics. If any of you are thinking of doing it yourself feel free to ask any questions.
*all connections behind the grill and lights are done with quick disconnects or quick splices. They are wrapped in electrical tape as my attempt to keep rain and/or moisture out.
Lights = $40
Light bar = $100
Wire, connectors, switch, relays, and fuses = $30
Pretty happy about $170 total cost, and the knowledge I gained doing it all.
Took me about 4 hours.
I love where I mounted the switch and how factory it looks. Lights are very bright, easily adjustable, and good quality.
I know a lot of you were interested in this (sarcasm), but if anyone is here's some pics. If any of you are thinking of doing it yourself feel free to ask any questions.
*all connections behind the grill and lights are done with quick disconnects or quick splices. They are wrapped in electrical tape as my attempt to keep rain and/or moisture out.
Last edited by Bossgame; Aug 10, 2014 at 11:21 PM.
Senior Member
Joined: Jun 2009
Posts: 736
Likes: 65
From: Edmonton, AB
Responded below. I see you've done most of your install already and it looks good. Hopefully the answers below will help but you had most of it on 
.
I'm not personally a fan of T-Taps as I see you've used... also, try and protect those +12V's from the relays... Tape them, do something. If they touch any of your chassis pop goes your fuse.
.I'm not personally a fan of T-Taps as I see you've used... also, try and protect those +12V's from the relays... Tape them, do something. If they touch any of your chassis pop goes your fuse
.1) I am running 4 lights at 100 watts a piece to equal 400 watts. 30 amp switch is rated at 360 watts, but since I am using relays to separate it all out and to take the load off of the switch, I will be ok running both relays to just that one switch correct?
You are correct. The switch is low current, and the relays use low current to energize (both should be lower than what the switch requires so there should be no issue here).
2) 100 watts / 12v = 8.33 amps per light. Therefore roughly 16.66 amps per relay, so running a 20 amp fuse between relay and battery per relay will be about the right size fuse correct?
Yep, 20 amps should be fine. I always recommend, fuse as close to the battery as possible (in case of an accident and the wire becomes crushed, the fuse blows if wire crimped anywhere up to battery preventing a possible fire - and load protection of course). You did this so you're fine.
3) Coming off of the switch, I know where I'm grounding it, and I know how I'm getting it to relay, but where is the best place to draw the +12v power to the switch from? Can I run a fused line directly from the battery? Or do I splice into hot cigarette lighter wire? Or is there a better wire to splice into?
You can go directly from the battery or cigarette lighter (remember, it's very low current as you have the relays triggering for the high current) so the load will be so minimal it won't matter. The only thing to keep in mind is if you go direct to the battery or cigarette lighter, those are both ALWAYS HOT. So if you turn the key off and leave your lights on, your battery is draining nicely. A better spot would be to tie into the ignition or accessory wire under the dash that way if the key is off, so are the lights.
4) Where have you guys put the switches? Looking for best possible place.
I have factory fog lights but what I did was added 3 micro switches between my park assist and cigarette lighter. One for Daytime Running Lights (Canada eh?), second to flip my daytime running lights to fogs or standard headlights, third to allow foglights to turn on with highbeams (I can control this independently though with my standard foglight switch).
You are correct. The switch is low current, and the relays use low current to energize (both should be lower than what the switch requires so there should be no issue here).
2) 100 watts / 12v = 8.33 amps per light. Therefore roughly 16.66 amps per relay, so running a 20 amp fuse between relay and battery per relay will be about the right size fuse correct?
Yep, 20 amps should be fine. I always recommend, fuse as close to the battery as possible (in case of an accident and the wire becomes crushed, the fuse blows if wire crimped anywhere up to battery preventing a possible fire - and load protection of course). You did this so you're fine.
3) Coming off of the switch, I know where I'm grounding it, and I know how I'm getting it to relay, but where is the best place to draw the +12v power to the switch from? Can I run a fused line directly from the battery? Or do I splice into hot cigarette lighter wire? Or is there a better wire to splice into?
You can go directly from the battery or cigarette lighter (remember, it's very low current as you have the relays triggering for the high current) so the load will be so minimal it won't matter. The only thing to keep in mind is if you go direct to the battery or cigarette lighter, those are both ALWAYS HOT. So if you turn the key off and leave your lights on, your battery is draining nicely. A better spot would be to tie into the ignition or accessory wire under the dash that way if the key is off, so are the lights.
4) Where have you guys put the switches? Looking for best possible place.
I have factory fog lights but what I did was added 3 micro switches between my park assist and cigarette lighter. One for Daytime Running Lights (Canada eh?), second to flip my daytime running lights to fogs or standard headlights, third to allow foglights to turn on with highbeams (I can control this independently though with my standard foglight switch).
Last edited by homer; Aug 11, 2014 at 12:49 AM.
Thread Starter
Senior Member
Joined: Apr 2014
Posts: 366
Likes: 13
Responded below. I see you've done most of your install already and it looks good. Hopefully the answers below will help but you had most of it on . I'm not personally a fan of T-Taps as I see you've used... also, try and protect those +12V's from the relays... Tape them, do something. If they touch any of your chassis pop goes your fuse .
. I'm not personally a fan of T-Taps as I see you've used... also, try and protect those +12V's from the relays... Tape them, do something. If they touch any of your chassis pop goes your fuse .What don't you like about the t-taps? How do you do it?
Glad to hear I did most of it right! Hah