Correct wiring for a utility light

[CJAKE7]

There is probably a thread for this but could not find it. I want to wire a utility light mounted on my rear bumper for night time trailer hookups. The light is a mini six bulb LED bar light. Not sure of wattage. I have a 20 amp Lighted Daystar Rocker Switch(20 amp). My question is do I need a relay - if so how is that wired(where do I get the feed from, size?, type?). If I don't need a relay, can I just tap into the fuse box and run power through the switch to my light. I am unfamiliar with relays and when they are needed and not needed.

 

[PaRenegade]

The nice thing about LED's are they use less amps and produce more light. You might be talking about 3 amps or so for your light, so no relay is needed. I don't recommend tapping into the fuse panel for anything other than a radio memory power source. I'd run a new, fused, hot wire and ground wire(14ga. min.) from the battery. Your switch is plenty adequate for this light.

 

[Lumpy Grits]

Use a cigarette lighter for the powder source and use LED bulbs.
Have it wired directly to the battery on a 20amp fuse. Run 12 gauge stranded wire to the outlet mounted at the back of your Jeep.
Good luck,
LG

 

[052]

I just finished mounting a set of Rough Country 2 inch LEDs on the rear of my CJ5 . The wiring that came with mine had a relay and in-line fuse. I ran mine through a carling switch mounted under the dash. They work great.

 

[SCSEAJAYSEVEN]

Use a cigarette lighter for the powder source and use LED bulbs.
Have it wired directly to the battery on a 20amp fuse. Run 12 gauge stranded wire to the outlet mounted at the back of your Jeep.
Good luck,
LG

Like what was stated above, the light "might" draw 3 amps. No need to use a large gauge wire, a 18ga. or even a 16ga. wire is plenty. I would use a fused (3 or 5 amp) dedicated wire to the lamp from the battery or other known "hot" source through a switch for your lamp. No need for "overkill" in this situation...

 

[CJAKE7]

Thanks for the feedback guys. I know very little about wiring - just basic AC house wiring. Can anyone give me a little theory on the difference between getting my feed from the fuse box vs. the cigarette lighter? Also, do I T off the lighter or use the direct line and no longer have a cigarette lighter.

 

[PaRenegade]

Well the reason I made that comment is because the main supply wire to the fuse box was designed for a known amperage load, plus a little more for a safety factor. Your light load would probably be fine in this case since it's so small. But in general, it's better to get a direct source for power right from the battery so you eliminate any excess connections / failure points, or overload the panel. Remember, loose connections can build heat.
It also seems that if you have to run wires to the fuse panel, it's not much further to run to the battery. And remember, distance builds resistance and each wire gauge has it's limitations not just for amperage but for distance too, which varies with the amperage.
Using a cig. lighter would be fine to create a power port. In fact I did this very thing on my build. I ran two 8 ga. wires to the rear of my Jeep (+&-) to a waterproof box, added a fuse and a relay (so I could control it by a switch inside), and then went with some 12ga. to a weatherproof cig. lighter/power port mounted to my spare tire carrier. It's like creating an outside electrical receptical but for 12v in a vehicle.

 

[Lumpy Grits]

Like what was stated above, the light "might" draw 3 amps. No need to use a large gauge wire, a 18ga. or even a 16ga. wire is plenty. I would use a fused (3 or 5 amp) dedicated wire to the lamp from the battery or other known "hot" source through a switch for your lamp. No need for "overkill" in this situation...

Not 'overkill' to have your wiring match the load capability of the outlet
Never know what you might run in the outlet 'down-the-road'
LG

 

[Lumpy Grits]

Thanks for the feedback guys. I know very little about wiring - just basic AC house wiring. Can anyone give me a little theory on the difference between getting my feed from the fuse box vs. the cigarette lighter? Also, do I T off the lighter or use the direct line and no longer have a cigarette lighter.

Battery IS your power source. You can access it with engine off.
KISS in wiring and you still have full powder rating of the cig outlet.
LG

 

[Jimbos76cj]

Only issue running a 20 amp fuse and 12 ga wire for a light that only requires 3 amps is your allowing more heat to be created if there is a ground short. if you want to run 12 ga what ever floats your goat but your fuse should only be a little bit bigger then the amp draw of the item being used so if it ground shorts itwill quickly pop. If over kill was awesome for fuses we would all have a fuse box full of 30 amp fuses.

 

[Lumpy Grits]

If you fuse at the battery-it's not an issue if the outlet is grounded where it mounts. Assuming you have proper gnds through out your jeep.
You will also have less voltage loss and resistance(heat)with the larger ga. stranded wire.
LG