Best place to get power for driving lights?

[HotWheelsBurban]

Hi all, going to put driving lights on Rawhide ('97 Chevy Silverado crew cab) and I'm wondering where would be the best place to get juice for the lights. The power wire has a 15amp fuse in it, but the wires themselves are like 18 gauge. Lights are small halogen, like a lot of people used before LEDs became a thing.
I don't think I want to hook them directly to the battery, even with the fuse protection. Is there a place in the fuse block for adding accessories? Maybe these sound like dumb questions, but my knowledge of this kinda stuff is very limited.....
Thanks in advance!

 

[shovelbill]

Hi all, going to put driving lights on Rawhide ('97 Chevy Silverado crew cab) and I'm wondering where would be the best place to get juice for the lights. The power wire has a 15amp fuse in it, but the wires themselves are like 18 gauge. Lights are small halogen, like a lot of people used before LEDs became a thing.
I don't think I want to hook them directly to the battery, even with the fuse protection. Is there a place in the fuse block for adding accessories? Maybe these sound like dumb questions, but my knowledge of this kinda stuff is very limited.....
Thanks in advance!

Hi...I'm glad you are going with halogen instead of the Star Trek LED things, lol. I can't stand them. Either way, 18 gauge isn't ideal, no matter what, IMO, and for any light set I put in, I use a relay harness. I had an old KC harness kickin' around and used that to power my 6" round Cibie fog lamps.

I think it was like this one:

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Yes, I grabbed power from the hot block on the wall.

What lights do you have...bulbs? I think I have a set of Cibie Airport 135s in my stash if you may want to upgrade later. They're really good little lamps. I use one on my daily rider bike as an auxiliary high beam. I have them in amber too.

 

[HotWheelsBurban]

They're halogen bulbs; the lights are a set I got at Northern Tool for $28. So I don't expect them to be perfect, but they're what I can afford now. I got some hardware to bolt them under the bumper today. The main point is to get more lighting on the front of this truck, so we can see the road ahead.
I'm guessing these don't draw more than 15 amps because that's the fuse in the holder.

 

[shovelbill]

They're halogen bulbs; the lights are a set I got at Northern Tool for $28. So I don't expect them to be perfect, but they're what I can afford now. I got some hardware to bolt them under the bumper today. The main point is to get more lighting on the front of this truck, so we can see the road ahead.
I'm guessing these don't draw more than 15 amps because that's the fuse in the holder.

Mount them up. I'd still use a harness to get the most out of them, and you can always change the lamps if those don't do what you want them to do. Those may be 55-watt H3 bulbs, so 15 amps will do. Just hook them up the way they come and 'see' how they do at night before investing any more into that system. The bus bar is convenient and straightforward.

 

[GoToGuy]

What's the bulb wattage? Get out " Ohms Law " do the math and check chart for recommend wire size. Double check your kit supplied correct size wire. Could always add relay that gets power from acc side. So has power key on or acc on. Good luck.

 

[Erik the Awful]

For halogen lights, I recommend using a relay. You can use the 18ga wire on the control side of the relay, and 12ga on the power side. It's acceptable to tap off the battery with a fused wire, or you can install an underhood fuse block to run accessories. I have a maxi-fuse block robbed from an RX-7 on WCJr.

There are charts for max amperage per wire gauge, but I've found a lot of bogus info lately from wire companies trying to sell you stupid big wire, i.e. 4ga wire for a 20 amp draw.

 

[HotWheelsBurban]

For halogen lights, I recommend using a relay. You can use the 18ga wire on the control side of the relay, and 12ga on the power side. It's acceptable to tap off the battery with a fused wire, or you can install an underhood fuse block to run accessories. I have a maxi-fuse block robbed from an RX-7 on WCJr.

There are charts for max amperage per wire gauge, but I've found a lot of bogus info lately from wire companies trying to sell you stupid big wire, i.e. 4ga wire for a 20 amp draw.

What sort of relay would you recommend? You know way more than I do about electrical stuff, so I defer to your judgement!
I think the ground wires are the only ones that are 18ga. The wires between the lights and the power leads look a little bigger, so they're probably 16ga. Not the greatest setup, but it's what came with them, and I don't want to have to redo all of it.....

 

[Nad_Yvalhosert]

A generic 50A, 4 pin relay would be fine. One that has an eyelet to attach to fender would be better.
Most have a schematic on the case, a low Amp coil circuit that the switch powers up, and a high Amp side.

Low amp: Route the power from an ignition fed fuse tap, through the switch, to the relay.
High amp: Route the power from the stud on the fuse box and put in a 30A maxi fuse.

Make sure there's good grounds, one for the relay, and a better one for the lights. Dielectric grease is your friend with ground eyelets. Spread the love.

 

[Nad_Yvalhosert]

Auxiliary driving lights.

I drive my truck in the dark fairly often, and in nasty weather. It’s a wt model with the sealed beam headlights. I have replaced them with units from headlight revolution and 55/100watt h4 bulbs. I have also ran a wire harness so that the headlights draw power directly from the battery instead...

www.gmt400.com

Post #4 has a good description of the relay post numbers and function. Thanks go to @Frank Enstein

 

[Erik the Awful]

What Dan said. The standard auto relays work fine. There are two terminals on the low-amp control side, and three terminals on the high-amp load side. I've wired stuff up for years, but I still have to put on my reading glasses and carefully check the terminal numbers against the wiring diagram every time I wire something up. I have also run into relays that use the same socket, but the terminals are different! Always check your relay's diagram.

In the pic below, terminals 85 & 86 are your low-amperage control circuit. Your switch will be on this circuit and 18 gauge wire is perfect.
Terminals 30 and 87 are your high-amperage load circuit. I'd use 12 gauge wire here.
Terminal 87a is used when you want the relay to open a normally closed circuit, also 12 gauge in the circumstances you'd use it.
For fun, wire power to terminal 30, jump terminal 87a to terminal 85, and ground terminal 86. Congratulations! You've just made a buzzer from a relay.

Relays are not polarity sensitive, so it's up to you how to run power and ground. The standard is to use terminals 30 and 85 for (+) and 86, 87, and 87a as (-) even though the diagram below shows 86 as power and 85 as ground.

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I'd suggest running a single 12 ga wire through a 20a fuse to terminal 30 and a 3" 18 ga jumper wire from terminal 30 to terminal 85. Run from terminal 86 with 18 ga wire to your switch, and from the other side of the switch to ground. Run 18 ga wire from terminal 87 to your driving lights, and then ground the other side of the lights, and you're done.

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