Young_ford_fanatic

Hello.. I recently got some 100 watt cheapo offroad lights:
and wanted to know if I ran some heavy duty switches (12 volt 20 amp) with one switch to each light and some 14 guage wire if I could wire them like this: battery to switch then switch to light.

Really just want to know what the dangers of this would be and why it wouldnt work if it wont and what would be a better way if there is one.
Thanks!
-Joe

elricfate

As I stated in another thread just a minute ago, you should wire them as

Switch -> Relay -> Light
..................|
..................12V Source

The switch should trigger the relay, the relay should get power directly from a fused battery connection and feed it through the relay to the light. That way your switch is not handling the load for the light, it's only triggering the relay which is designed for handling standing electrical loads.

Young_ford_fanatic

I know my setup wouldnt be ideal but would it work? or could I wire it from a connection in the fusebox instead? I really dont want to use a relay but will if I absolutely have to

techrep

iTrader: (1)

It would work until your wire got hot and melts your switch and burns up your dash or melts your fuse box. suggest you follow Elricfate's advice..

jp360cj

Just curious, why are not wanting to use a relay? It will actually be more work work to wire each light directly to it's own switch than it will be to wiring both lights to a single relay and switch. We can help walk you through how to wire up the relay. Also, using the relay, you can power the switch from the interior fuse panel and only have to run 1 wire through the firewall (vs 4 wires through the firewall). What year/model truck are you working with?

Young_ford_fanatic

I have 4 switches mounted already Im mounting them overhead and using a relay just seems like too much of a headache because im keeping the 4 switches (the look pretty sweet) and then four relays just seems like a lot of unnecessary work if I could just get away with going from battery to switch to light

jp360cj

Using relays will not only be safer, it will actually be less overall.

Here's why:
You will have a very long wire run to the lights if you wire straight to overhead switches. This will cause you to need larger wire to minimize voltage drop to the lights. Then you'll need to run a minimum of 8 wires into the head liner (1 in and 1 out for each switch). If you use the relays, they can be mounted in the engine bay. The load carrying wires will go from the battery, through a fuse, then to the relay, then straight to the lights (or whatever component you are wiring). To get power to the switches, you can pull from the interior fuse box (this will give you the option of always hot, or only hot when the key is on). This 1 wire can power all the overhead switches. Then you just need a wire from each switch to relay, which can also be a small diameter wire. So as few a 5 smaller diameter wires vs 8 the other way. You would only have 4 wires to pass through the firewall with the relays, vs. 8 without. And you'll still have 3 empty switches that can be used later. Since you don't need to worry about sizing the wire to the switches according to the load on the relay, you can do all the overhead wiring now, and just cap the wire in an easily accessible location. When you want to add more lighting, just add a relay and hook up a couple wires.

Young_ford_fanatic

Ok I guess I will have to do it a better way, as my name implies I am young... and still stupid so Im still learning as much as I can and was hoping I could do it without all the complications of relays and fuses but I guess theres no way around it. Now its just a matter of not screwing it all up(because I probably will) so I am still open to all the advice you are willing to give, if it helps the switches I will be using are these:

Lethal Weapon

Please use relays!!!!
A 300 watt light bar can melt a heavy 12 gauge wire!
Below is a link to a great video and is very informative.
I can't stress on safety enough...and doing it right.

Watts/volts= amps
300/12= 25 amps..... even big 12 gauge wiring is only rated for 20 amps.

When you use a relay... all the main load is thru the relay & internal coil & contacts. Then the rest of the wiring has only milliamperes running through them.

(Plus use "trigger wires" as your power in and use a smaller gauge wire without risk of burning up your wires, switch.... or even worse: your truck.

Bubbabiker

For high wattage applications you can run dual relays (one for each lamp) to minimize the stresses on the relay themselves. Something that I learned back in the 1970's running modified Cibie Super Oscars.