jaythenewguytojeepn

My question is....can I hook up a rear light bar and a front light bar with 2 different switches to the same relay???

TheNerd

Only if you want them to come on at the same time... and only if you are pulling under 35A. Think of the relay AS the switch, you just have the physical switch located remotely. You will need to have 1 relay for each independent circuit that you want to control with one exception:

IF you want to control your lights in an "OR" fashion (either the fronts are on OR the rears are on....all the time) then you can use a 5-prong relay that has an 87 and 87a pins. One of which is always hot when the switch is ON, the other is always hot when the switch is off. You would still want to control On/OFF of the rack lights, however, which would end up meaning a 2nd relay.... so you are right back to where you started. 1 Circuit; 1 Relay.

jaythenewguytojeepn

Lol..thanks for the input time to buy more relays ..thank u

getandistr

Do you even need a relay? I've wired lights before and I just use a switch and a fuse.

jakbob

unless you like to run thick wiring yes. lights can pull a lot of current. then you need to get a bigger switch to handle the amperage that you are pulling. a relay lets you control a lot of current, with a trigger. and there will be no fires.

mainly you dont want your truck to catch on fire due to faulty wiring right? then wire it with a relay.

jaythenewguytojeepn

I am hooking up 440 watts on one light bar and 110 watts on the rear light bar...

jaythenewguytojeepn

That's why I want the relay I was checking if I could run to different switches to two different light bars using the same relays...iam running AWG 12 g

jakbob

so then use the following formula. you know your jeep is a 12v system, and we will just make front and back diff circuits.

current draw = volts / watts

front 440w/12v=36.6 amps
back 110w/12v=9.16 amps

you definitely need to use relays. if you wire them together you will need to find a 50 amp relay.

TheNerd

440W! As stated below (er.... above) that is about 37A. Most automotive relays are 30A or 35A, which is going to put you in a bind. If you are REALLY going to pull 440W off 1 relay (if you can find one) then you will want way more the 12ga. wire (that power puts you in the 8ga range for a single circuit)

Alternatively, you can wire it up with one switch going to 2 relays (sort of the opposite of your original questions). You would then have (2) 220W circuits for your front lights that could operate on 12ga. wire. You would still want (2) fuses (1 fuse per circuit)... just to re-iterate (no cutting corners!).

jaythenewguytojeepn

Sorry...its 330 watts front 110 in the rear ...total 440..I have 2 40 amp relays. And 2 35 amp toggles for the switches ....so can I hook up both relays to one set of lights and one switch????

Marcucco

The switches for the relays don't carry much power. The relay is actually the switch for the lights, and the toggle is the switch that turns on the switch.
Since the relay is the switch between the battery and the lights, you need to supply enough amperage and have heavy enough wires between the 3. (battery relay and lamps).

The toggle and it's wiring only require a couple of amps tops. There's no harm in bigger wires but your fuse needs to match the draw of the trigger side of the relay and it needs to be on it's own circuit, separate from the lamps.

TheNerd

- Technically yes, but I don't think that is what you want to do.

I am going to assume you want to operate your front and rear lights independently. If that is the case, you will need 1 relay for the front power circuit, and 1 relay for the rear power circuit (you existing 40A relay should be fine for 1 full circuit; the 12ga. wire is smaller that I would use (for the front), but it *should* be ok). The general rule of thumb when wiring is to use twice the wire gague rating (amperage wise) you think you need and the smallest fuse that will handle your intended load.

As mentioned you toggle switches are WAY overkill. The current draw to initiate a relay is generally REALLY low. But, if you have a 3-way switch (On-Off-On), then you can wire 2 circuits (in this case, the front lights and the rear lights) to the 1 switch. If you only have 2-way switches (on-off), then you need 1-Switch & 1-Relay for each the front and rear light circuits.

jaythenewguytojeepn

What if I hooked up both relays to one light bar..by Ying off the wires to the lights and to the switch....

TheNerd

???.... Just do this, but size the wires accordingly:

Marcucco

You would need separate relays if you wanted to turn one set on and not the other.
If you're only ever going to run them all at once, go with one relay, just be sure the relay, fuse and wire match the draw of the lights.