Wiring roof lights

[1Jesusfreak]

If there is already a thread on this please let me know. What I would like to know is if I can run 4 6" KC lights off of one switch, and if so how do I go about doing it. I ask this because when I got my Cherokee it already had four lights on top wired in a series and I would like to leave it that way if I can. I really don't want to have two switches. If anyone could help I would very much appreciate it. Thanks

 

[Toyotanut]

it's going to depend on the the rating of the switch if you will be able to use one switch or two.

 

[TreeClimber]

You need to use a relay.

The switch powers the relay.
When the relay is powered, it then powers the lights.
I'm *guessing* the current lights are already wired thru a relay. If it was my rig, I'd use the existing switch to power two simple relays, one for each pair of lights.

But then again, if it was my rig, I would NOT have 4 big lights.

Are you planning on running the BAJA 500 at night? Why so much candlepower?

edit... You ain't plannin' on running 8 lights are ya? The 4 existing, and another 4 KCs?

edit2... You can get pulled over (and a ticket) for leaving un-covered KCs on a roof, even though they're OFF. Spotlights higher than the headlamps are illegal, except when used off-highway. So make sure you get some KC covers ( ) to repel the local police.

 

[1Jesusfreak]

TreeClimber the lights were on the rig and wired together when I got it. They are not hooked up at this time.
I was trying to avoid seperating the wires, but will if I have to. Now that I understand how they work. Can I leave the lights the way they are and run two relays in a series or just put in a 70amp relay? ( if I understand this, one relay will not work for the 4 lights)
As for the candlepower I don't see real well at night and would really hate to mis a turn on some trail if ya know what I mean.
My lights are all covered but thanks I did know that could happen.

 

[ain'tstuckjustresting]

If they are just standard 55w H3 bulbs a standard 30amp relay should run 4 lights pretty easy. If they are 100w or 150w I'd use a 30amp relay per pair and use 1 switch to latch both relays.

 

[ain'tstuckjustresting]

Also, If you do run all 4 lights together. Wire them in parallel not series. Too much voltage drop across 4 lights.

 

[1Jesusfreak]

ain'tstuck, not sure what they are rated. If 55w H3 is what they come with, I don't think they have been changed. Not sure how to tell?
Thanks for all the help. I see now that it is really not that difficult.

 

[ain'tstuckjustresting]

Just pull the bulbs out. They are marked. KC uses the big sealed beam lights that are 100w. You can also get the small bulbs that go in from behind in 55, 100, or KC makes a 150w version. My old daylighters came w/ 55w H3's and my Comp daylighters were sealed beam 100w.:awesomework:

Now I have Hella's that came with 55w and swapped in some 100w bulbs.

 

[1Jesusfreak]

Thanks I will check them tomorrow.Ya I got the big sealed beam lights, I'm thinking 100w
ain'tstuck, is it possible to use a higher amp relay? with lights wired they way they are?

 

[Travis1]

So, how big is the wire going from the relay to the lights?

 

[ChopTop84]

100 watt bulbs draw roughly 9 amps (give or take a little) on a 12v system. So 4 lights, times 9 amps equals 36 amps. I've burned up some of those 30 amp relays by running them too close to their rating for a long period of time, so yeah, I would run at LEAST two relays (18 amps per pair of lights).

The relay itself requires hardly any power to turn on, so pretty much any switch you like, you could use. Lighted, rocker, toggle, whatever, and you can daisy chain multiple relays off one switch.

I really, REALLY *REALLY* like pre-wired relay harness plugs. You can get them for pretty cheap online. I would recommend the double relay harness such as this one from parts-express: Click me!. I have nothing to do with them, I just have one of their catalogs, and it had that double relay pre-wire harness. Then use the newer style heat shrink, water tight butt connectors and you've got almost a factory looking setup!

As for wire size, it all depends on distance, and amperage. From the battery to the relays, I would run a pretty decent size FUSED supply wire, prolly in the 8 gauge range, and then run either a 10 or 12 up to the lights.

If you need more fuse circuits, but dont want a pile of wires going to your battery, you can get a blueseas circuit block from west marine. Gives you like 6 additional circuits up to 30 amps each, with a total combined draw of about 100 amps. I have one of these in my superduty to run all my radios and strobe lights and stuff. Used a #4 wire to the blueseas box direct from the battery, then each piece of equipment gets its own fused circuit.

 

[1Jesusfreak]

Nothing at this time. That is why I'm trying to get all the info I can before hand. But it will be 10 or 12 gauge.

 

[1Jesusfreak]

Thanks ChopTop84, that is the kind of info I was looking.(along with what I have already been given) The more the better. What do you think about running the lights in a parallel instead of the series like TreeClimber said. He is right about the voltage drop. I want to only have to do this one time and I want it to be the right way.

 

[ChopTop84]

Thanks ChopTop84, that is the kind of info I was looking.(along with what I have already been given) The more the better. What do you think about running the lights in a parallel instead of the series like ani'tstuck said. He is right about the voltage drop. I want to only have to do this one and I want it to be the right way.

No, parallel is the correct way to wire them, this way, each light gets a full 12v. It will require running 4 hots up to your lightbar, one for each light. If you wired them in series, then you would effectively be supplying each light with only 6 volts if done in pairs, or 3 volts if all 4 lights were in series.

I can draw you up a schematic pretty fast if you want. Im no stranger to electricity.

 

[TreeClimber]

It will require running 4 hots up to your lightbar, one for each light.

What?

You only need to run 1 hot to the lightbar, and each lamp T-s off of that hot.

You only need to run 1 ground wire to the lightbar, and each lamp T-s off to that common ground.

Make sure to adequately protect the wires from the environment. (Wire tape, shrink tube, etc)

 

[ChopTop84]

What?

You only need to run 1 hot to the lightbar, and each lamp T-s off of that hot.

You only need to run 1 ground wire to the lightbar, and each lamp T-s off to that common ground.

Make sure to adequately protect the wires from the environment. (Wire tape, shrink tube, etc)

You could do it that way too, but I hope your running some decent sized wire. Also, if he's running two relays (2 lights per relay) then he's looking at at least 2 hots up to the bar.

You could run two relays into one big wire, but what if one relay fails, and all the power goes thru the other relay? You would never know until that relay started smoking from over current.

No, the right way is going to require more than one hot wire up to the light bar. Also, even the ground wire will need to be rated for the current, so its gonna be either a very big single, or a couple of smaller ones.

Ive spent years wiring boats that have to meet USCG and ABYC wiring standards, so I transfer those same standards to automotive wiring because, really, they are good standards, and your less likely to burn your rig to the ground from bad wiring (which, by the way, most burned rigs I have ever dealt with, came from bad wiring).

 

[1Jesusfreak]

Now Now lets all play nice Just when I thought I was getting a handle on this, you guys go and mess my head all up. So if the lights are of low watt then I can run all four off of one relay? ( do you both agree) and if they are not then I will have to split the wires and make up two pairs? (do you both agree). And either way I can still run all four from one switch? (agree)

 

[ChopTop84]

Now Now lets all play nice Just when I thought I was getting a handle on this, you guys go and mess my head all up. So if the lights are of low watt then I can run all four off of one relay? ( do you both agree) and if they are not then I will have to split the wires and make up two pairs? (do you both agree). And either way I can still run all four from one switch? (agree)

If they are say, 50 watt bulbs, thats 200 watts total draw, or about 18 amps (give or take). You could run that all on one 30 amp relay, and off of one wire, and off of one switch. Probably 10 gauge wire just because of distance and voltage drop. Ground wire needs to be 10 gauge also. Fuses should be within 15 inches of the main power source, and you fuse to protect the wiring, not the load. The wiring for the switch to the relay can be your typical 18gauge wiring, but the load wires need to be beefy.

 

[ain'tstuckjustresting]

Pretty much:awesomework:

 

[1Jesusfreak]

Thanks ChopTop84 I will take that schematic that you talked about before. I should be able to do it with that in front of me. Sorry if I am making this harder than it should be, as you tell this is not one of my strong points this is all new to me. I will pm you my email address. Remember I will require lots of detail.