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Front lightbar wiring question

#1
Okay well I just finished my front bumper for my 99 ford f-150. Now I have 4 procomp 7 inch lights with 100 watt bulbs in them that I need to mount. I was thinking of running power to the light switch from the battery with a 20 amp fuse in between. Then running power from the light switch to a relay. Then run a wire with power from the relay to the 4 lights. Should I run 1 wire then split it in to the 4 lights or should I run 1 relay for every 2 lights? Let me know what you guys think or how you have yours wired. Thanks ahad of time for your help.

Roger
 

DesertGuy1

Well-Known Member
#2
As the saying goes, there are alot of ways to skin that cat. Personally, I don't like running high amperage through a switch, especially for any length of time (such as off-road lights). I favor relays, although I'm sure an argument is there not to run them in a "race-specific" car. However, an electrical system built right, relays should not be an issue in either case.

Below is an option that could be considered to wire them with the following exception... I would swap the wires on 30 and 87 on the relay. That way 87A would not be "live" when the lights are off. Or simply find and use a 4 pole relay.

Since you are using 100w lights, that is "roughly" an 8.33amp draw, so paired up would be 16.66 - which would be a 20amp circuit. The simple Bosch style relays are 30amp, spending more money can get you higher amp relays but not necessary. So that being said, I ran two circuits - each 20amps and powering a pair of lights. Keep in mind, you can have the same switch power both relays (you would just "jump" the wire from 85 on one relay to 85 on the other). The above cct's are how I ran them in my car, as below.





...and as always, this opinion is worth what you paid for it.
 
#3
Wow! Thanks for the info! I searched all over the internet for exactly this and could find anything. You hit it right on the nail. Really, really, really appreciate this. I think I will just use this set up with the 2 toggle switches. Once again, Thanks. I'll let you know how it turns out.

Roger
 
#6
Hey DesertGuy1 well I wired up my lights today and everything came out perfect. Never really wired up any lights before but the help you posted was perfect. I will see if I can get a pic up this weekend so you can check out my finished product.

Roger
 

DesertGuy1

Well-Known Member
#7
What progam do you use for drawing?
I use Adobe Flash CS3. It is not really designed for schematics, but seems to work well and its a program I know... so it wins by default.

I wired up my lights today and everything came out perfect.
Roger, glad to hear the above helped out... probably saved a little coin in the process. Post a pic when you get a chance, everyone likes pictures.


Steve
 

johnnyweb

Well-Known Member
#8
Fore a daily driver more stock type vehicle i like the idea of the relay as you can power the toggle switch from low amperage source. For a race only vehicle i see them as one more thing to go wrong. In a race application i ellimminate the relay from the system and run a heavy duty toggle switch with the right amount of amprage rating and replace the fuse with a self resetting circuit breaker. Also i hate the flat blade style connectors on relays, prone to falling of off or corrosion. But thats just my 2 cents.
 

osborne

Well-Known Member
#9
desertguy1, I was just working on my light bar and getting ready to wire. (which i've never done before). this just answered my ?'s, except- I have 5 hids, would i still wire them the same? can I put more on each circuit? thanks for the help and great diagrams.

aaron
 

Zambo

Well-Known Member
#10
Fore a daily driver more stock type vehicle i like the idea of the relay as you can power the toggle switch from low amperage source. For a race only vehicle i see them as one more thing to go wrong. In a race application i ellimminate the relay from the system and run a heavy duty toggle switch with the right amount of amprage rating and replace the fuse with a self resetting circuit breaker. Also i hate the flat blade style connectors on relays, prone to falling of off or corrosion. But thats just my 2 cents.
I agree. We run 50A triple sealed switches in the racetruck with no relays. In my own truck however, I do run relays. Actually have 4 LaPaz HIDs on one relay with a 30A fuze, works fine. I'd bet you could run 5 no problem but I'd use a 40A relay/fuze.
 
#11
desertguy1, I was just working on my light bar and getting ready to wire. (which i've never done before). this just answered my ?'s, except- I have 5 hids, would i still wire them the same? can I put more on each circuit? thanks for the help and great diagrams.

aaron
I'm not derestguy, but I think I can answer your question, mostly.
If you lights are 100w, pulling 8.33amps, then three would pull 24.9 amps, 4.9 amps over a standard 20amp relay.
You could just run one switch to two relays, then it should work fine.
 

DesertGuy1

Well-Known Member
#12
Aaron, one thing that I learned by doing my wiring is there are a number of ways to accomplish the same thing. You can buy different components to handle different loads... it just depends on how much you want to spend to what you want to accomplish, IMHO.

I am in the process of converting all of my lights over to HID and will keep the same lights (inner/outer) on their circuits. From what I understand, I could put all four lights on a single circuit, but since I want to have the flexibility of different lighting options, I will keep it how I have it. A good friend has 5 HIDS and has them with three on one circuit and two on the other, if that helps at all. That way he can run different options when needed.

When I did my wiring, I wanted a measure of "overkill" in regards to a safety margin in the wiring harnesses. I figured just because it "could" be done a certain way doesn't mean it "should" be done that way.


Steve
 

loufish

Well-Known Member
#13
By splitting up the lights on two separate circuts you add some survivabilty...A front nurf taking out and grounding say one light means not losing all 4 lights.
 

johnnyweb

Well-Known Member
#14
I agree i would not wire all 5 lights on one circuit. split them up in to two separate circuits so if one circuit has a problem you still have the other lights working on the other circuit. Last years Vegas to Reno i drove a truck for a fried of mine and we lost like 6 out of 8 0f the lights early in the night and it made for some interesting racing that night. I kept telling my self man we are going way to fast for the visabilty we have. Thank God for the Gps and a great co driver i had other wise im sure we would not have been able to run the pace we did with minimal lighting. Since then he has rewired his lights.
 
#15
Hey DesertGuy1 I finally managed to get a pic of my bumper on here. Well here is my finished product! Let me know what you think! Wiring great, lights work perfect! Ran the dual relays with dual switches since im on the road most of the time. Will do some real testing on the upcoming night race!

Thanks again!

Roger
 

Attachments

#18
Hi Desert Guy, if you can help, I would appreciate it. I am wiring some Hella Rallye 4000s and have the correct Hella wiring harness. The switch has two wires, both of which are green. One goes to the relay and the other is loose. I believe the loose wire goes to the headlights if I want to trigger the lights when the headlights come on, but I am not 100% sure on that. Since I don't want them to trigger with the headlights, but want to use the switch, can I just cut this wire? If so, that would mean the switch only has a single wire going to it. Will the switch still work, or does it need to be grounded or powered (there is no light in the switch)? I have the harness attached to the battery and the lights plugged in and grounded, but I am getting nothing.
 

_

Well-Known Member
#19
Craig, Desert Guy isn't around much anymore. So, I'll attempt to answer your question.

If you look at Desert Guy's drawing, you will note Pin-30 of the relay is +12V battery (fused.) Pin-87 is the output of the relay (when the relay is activated) and is to be wired to the lights.

Pin 85 and 86 activate the relay. In Desert Guy's drawing, Pin-86 is attached to chassis ground, and Pin-85 is supplied +12V via a toggle switch. Wiring in this manner will activate the relay any time the toggle switch is "ON."

An option to eliminate the need to source a second +12V for the Toggle Switch, is to eliminate the chassis ground wire from jump Pin-86 of the relay. Then Jump from Pin-30 of the relay to Pin-86 of the relay. Next, supply one leg of the toggle switch with Chassis Ground, and wire the other leg of the toggle switch to Pin-85 of the relay. Wiring in this manner will activate the relay any time the toggle switch is "ON."

(Basically, to activate the relay, you must have +12V on either Pin-85 or Pin-86, and the apposing pin (pin-85 or pin-86) must be wire to chassis ground.)
 

_

Well-Known Member
#20
Oops, I guess DesertGuy1 is still around, I just noticed a post from him from 2-days ago, Tuesday.

Sorry DesertGuy-1......!!!
 
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