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Wiring up my light bar... need help Please!

2K views 20 replies 5 participants last post by  axia 
#1 ·
Just to let you know, I already tried searching for this, to no avail.

So I'm wiring up my light bar and basically what I have is an over the windwheild bar with 5 lights, each with a possitive red wire and a negitive black wire...

Okay, so how do I hook these up? Does each possitive wire need a possitive feed from a power source, or is there a way I can hook them up sequentially? like power to neg, pow to neg, pow to neg, for all 5 of them? Then just ground the last one? And power the first one? Also, do I need inline fuses? Relays?

Thanks!
Max
 
#2 ·
You cannot hook them up in series + to - + to - or they will be very dim from a 12v DC power source (for instance (4) 12 volt lights wired in series would get about 3 volts each) the lights must all be wired in parallel (seperate feed from 12v power source) wired to a relay with a contact rating high enough to handle the amperage draw from all your lights.............
 
#4 ·
James04TJ said:
What is the wattage of the lights? You do not need a total of 10 wires down to your battery but you need to ensure that you are using a large enough conductor. Let's hear what wattage the lights are and we can go from there.
I beleive that they are only 55 watt cheapies from wal-mart or discount auto parts... but whatever

thank you for your responses so far. How do I know what size relay I need.
Also, I have a powerful amp and a small set of hella driving lamps on my bumper that are both already hooked directly up to my battery... seems like adding five more lights would be ........ sketchy....
 
#5 ·
(5) 55watt lights will draw about 23 amps with the vehicle off and about 20 amps with the engine on. You can use a standard 30 amp relay to control the circuit using 8AWG wire to supply the lights and relay. The switch that controls the relay can be run with 14 or 16AWG wire.

If you need more detail let me know.
 
#7 ·
kbtriumph said:
Please be sure to use in-line fuses to the switch and relay or you may end up with a TJ torch.
Correct. A 25A fuse would be appropriate for the load. Since you stated that you already have a set of lights on your bumper I will assume that they are operated via a relay. If that is the case you can use the same power feed that is already in place to provide current to the second switch. This will allow you to have a total of 3 wires into your dash instead of 4 and is completely acceptable. If your switch power is not currently fused a 3A fuse would be appropriate since each relay draws about 300MA.

Since it sounds like you have several things already on your battery you may want to consider and axillary fuse block such as those available from Bosch or from any high-end audio shop. I am not sure how large of an audio amp you have installed but if it is more than 100watts I would ensure that you are not running it anywhere near clipping while operating all of your lights since you will be close to maxing out your alternator.
 
#8 ·
First off, thank you so much for all the info.

James04TJ said:
Since you stated that you already have a set of lights on your bumper I will assume that they are operated via a relay.
They're not hooked up to any relay, they came with one so that you could only turn them on when the head lights were on, but now I have them directly wired.

The amp is above 100 watts, its a 600 watt.

But I'll never run it heavily when the lights are all on.

I'd like to hook up my 5 new lights to a seperate circuit. So is all I need some 8 gauge, a relay, an inline fuse and a switch? ( I already have 14 gauge). Also, where do I Ground the lights to?
 
#10 ·
Depending on the lights and light bar the lights may be able to get an acceptable ground throught the chassis ground (ie: no need to do anything since they may ground through the mount. Otherwise you will want to ground them out to the battery or a solid point on the chassis.

Sorry this isn't great but I am at work and did this in about 5min with paint.

 
#15 ·
axia said:
where do you find these relays? And what does a relay actually do / how does it work?
You should be able to find a 30 amp automotive relay at just about any auto parts store or radio shack. It should run you anywhere from $3-$7 and will look like this:


A 70 amp relay may be a little harder to find but you should be able to get one at a real auto parts store such as NAPA.

A relay is nothing more than a large switch that is remotely controlled. In this pic (sorry about that quality, all I have is paint) you can see the coiled line. This represents a coil (electro-magnet). When you energize the coil (throw the switch in your cab) the magnet pulls the switch portion of the relay onto the contact that allows current to pass from the battery to your lights. When you turn the switch in your cab off the magnetic coil within the relay is no longer energized and a spring returns the relay's switch contact to an open position.



Make any sense?
 
#17 ·
Those are fuses... There are several types of inline fuse holders but the type pictured is preferred.


Another option since it sounds like you already have a few accessories under the hood is to just install an auxiliary fuse block. Stu has a good write-up on his website about installing an auxiliary fuse block. http://www.stu-offroad.com/misc/fuseblock.htm I use the same one that he showcases in his install.

If you can't find one of those you can get something like this at a car audio shop:
 
#20 ·
Well if you are looking to run a single wire up the bar to supply all of the lights I would use a min of 8AWG if not 6AWG. 12 is VERY small and there is no way it will be able to safely handle that much current. If you use a stranded conductor rather than a solid you should not have any problems with being able to have it bend. I'm not sure what light bar you have but everyone that I have seen should be able to fit 4AWG.
 
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