How to Wire Off Road Lights?

[bzauche]

You don't always NEED a relay like I don't have one for my rear lights on my rack. Some switches can handle the load for the lights but some cannot and some power needs are beyond the limits of a switch and a relay is needed.

So if I were to run two switches, I'd be more likely to be able to not use a relay?

Solid state wiring (without relays) doesnt make you stupid. If you take everything into consideration, use the right switch and wire thickness, it'll work and be safe. Many trophy trucks dont use relays due to them failing under extensive constant vibration.

You can also run smaller load stuff (like say, an engine mounted small LED light) without relays.... LED stuff doesnt draw a big load.

Electrical... its complicated.

I'm realizing more and more that electrical is probably the most complicated thing I've had to work with...If I were to split up the lights into two sections, running two switches, and some big fat wire, would that work without relays? I think not using a relay would be best for my limited electrical knowledge...

 

[NW-ZJ-SCOTT]

Found this on pirate along time ago.. and saved it to my Photobucket..
It's helped me alot.. Now i have it memorized!

 

[xcm]

I'm realizing more and more that electrical is probably the most complicated thing I've had to work with...If I were to split up the lights into two sections, running two switches, and some big fat wire, would that work without relays? I think not using a relay would be best for my limited electrical knowledge...

Relays arent that difficult, once you get the hang of it.... you got this!

This is the path of electricity, from the battery, thru an inline fuse, thru the relay, to the accessory (light).

Notice my lines are thick? that represents your wire thickness... all the current that the lights use... travel thru this wire, size accordingly. NORMALLY, these two are not connected... and the light is off..

This is the control circuit:

When you Apply 12v to the left terminal, and supply ground to the right terminal, you trip the relay, and current flows thru the circuit above, and lights come on. The 12v at the left terminal, while 12v, has very little Amperage (flow), you could wire that with a tiny wire, as it sees little flow...

 

[xcm]

The image zj scott posted, works 100%, but i prefer to trip the ground side of the control circuit, if for no other reason than NOT having hot switches...

 

[bzauche]

Found this on pirate along time ago.. and saved it to my Photobucket..
It's helped me alot.. Now i have it memorized!

That's the most clear illustration I've seen yet! Certainly making a little more sense now...what's a fuseholder? Just another safety thing? Why does a line have to be run to the fusebox?

The image zj scott posted, works 100%, but i prefer to trip the ground side of the control circuit, if for no other reason than NOT having hot switches...

Gotcha!

I just need to make a list of everything I need...then I think I'll have a better understanding. The problem is, I still don't know exactly what I need! If I were to run 4 lights (2 sets of what ZJ's illustration is basically), I'll need 2 relays, 2 fuseholders, 2 switches (can I use just 1?), and a bunch of wire. Correct?

 

[scoobyxj]

The image zj scott posted, works 100%, but i prefer to trip the ground side of the control circuit, if for no other reason than NOT having hot switches...

?????? How do you not have hot switches? There is voltage there regardless of how you set up the switch.

 

[xcm]

?????? How do you not have hot switches? There is voltage there regardless of how you set up the switch.

switch the ground side of the relay... between pin 86 and ground.

 

[xcm]

That's the most clear illustration I've seen yet! Certainly making a little more sense now...what's a fuseholder? Just another safety thing? Why does a line have to be run to the fusebox?

A fuse holder is something like this:

it holds a fuse =)
I dont like the screw together, cannister type shown in zj scotts image. however the ones i linked to can be awkward once you add a couple.


The line, that goes to the fusebox, is the hot lead for the control circuit, remember when you have that 12v at pin 85, AND ground at pin 86... it directs 12v from 30->87. Take away either, and it'll turn off electrical to the lights.

 

[xcm]

 

[bzauche]

A fuse holder is something like this:

it holds a fuse =)
I dont like the screw together, cannister type shown in zj scotts image. however the ones i linked to can be awkward once you add a couple.


The line, that goes to the fusebox, is the hot lead for the control circuit, remember when you have that 12v at pin 85, AND ground at pin 86... it directs 12v from 30->87. Take away either, and it'll turn off electrical to the lights.

Got it!

PERFECT! I think I understand now. Just for my own sake, I am going to write what I see into words for you to verify. I think that picture helped a ton. Alright, here goes:

So from the battery, I'll have to 12 gauge (just for the sake of having a number) wires, each with a 30A fuse holder and fuse in the middle. Those wires are going to pin 30 of their respective relay. Also at pin 30, is a smaller wire going to pin 86. From each pin 87, I'll have 12 gauge wire running up the the lights, spliced into 2 at the top, for a total of 4 wires/lights. From each pin 85, I'll have a smaller gauge wire running to the switch. Also at the switch is a line for a ground, and a line to the fuse box (where on the fuse box?) Each light is also grounded.

Did I get it?

 

[scoobyxj]

That's the most clear illustration I've seen yet! Certainly making a little more sense now...what's a fuseholder? Just another safety thing? Why does a line have to be run to the fusebox?

A fuse holder holds a fuse. Which is a safety device that will protect the wiring and the vehicle from catching fire if there where to be some sort of short circuit in the wiring. It is a must have!

Gotcha!

I just need to make a list of everything I need...then I think I'll have a better understanding. The problem is, I still don't know exactly what I need! If I were to run 4 lights (2 sets of what ZJ's illustration is basically), I'll need 2 relays, 2 fuseholders, 2 switches (can I use just 1?), and a bunch of wire. Correct?

Here is how to figure what size wiring, fuses, and relays you will need to run for a given application.

Using this calculator. The 12volt.com ohms law calculator. You can determine how many Amps a circuit will draw by the voltage, and the wattage.

I know you said you wanted 4 100watt lights, but realistically 400Watts of light on you roof is beyond over kill. That and the fact I think you will find you almost never use them while driving because of the glare they will produce on the hood. I figured this using 55W lights instead.

220 Watts of bulbs (4 55w lights) / 13.8 volts = 15.9 Amps. We will call it a 20 Amp circuit because 20amp fuses are a common size, and 15.9 is under 20amps with 20amps being enough headroom to provide adequate protection but keep from needlessly blowing fuses.

Now knowing we need at least a 20amp circuit to power those lights we can determine the wire size based on the distance needed to be run using a wire chart. Wire size chart.

You can see that at 25ft for a 20A circuit is calling for 10AWG sized wire, and realistically you would want to go to the next size bigger (numerically lower) because it's right on the edge of what a 10AWG can deliver at that distance. That turns that 10AWG into 8AWG which isn't cheep! What you can do is divide that load up into two, or four wires. If you where to run a wire up for each light you would only need to carry 3.9Amps per wire. We will call it 5Amps for easy math. Now by looking at the chart you can see you only need a 18AWG wire to each bulb. That being said it's always a good idea to go one size higher than you need on your wire size upping that to 16AWG.

You will need a 20A water proof fuse holder. (These usually have 14AWG leads on them.)

A spool of 14AWG wire. (See fuse holder above for why)

A pack of 16-14AWG butt connectors.
A pack of 16-14AWG female push on terminals
A pack of 16-14AWG ring terminals
(I like to use the kind that have the heatshrink tubing built in.)

A standard 30A relay (I prefer to buy the ones with the harness.)

A switch of you're choice.

You can shop around for your items, but I have found that DelCity.net has some hard to beat prices, and hard to find items.

 

[scoobyxj]

Found this on pirate along time ago.. and saved it to my Photobucket..
It's helped me alot.. Now i have it memorized!

i would change one thing with this diagram for simplicity sake.

I would instead run the wire from the fuseblock to the switch to terminal 30 on the relay. As long as you use the correct size wire the fuse on the light side will protect the switch side just as good.

 

[bzauche]

Here is how to figure what size wiring, fuses, and relays you will need to run for a given application.

Using this calculator. The 12volt.com ohms law calculator. You can determine how many Amps a circuit will draw by the voltage, and the wattage.

I know you said you wanted 4 100watt lights, but realistically 400Watts of light on you roof is beyond over kill. That and the fact I think you will find you almost never use them while driving because of the glare they will produce on the hood. I figured this using 55W lights instead.

220 Watts of bulbs (4 55w lights) / 13.8 volts = 15.9 Amps. We will call it a 20 Amp circuit because 20amp fuses are a common size, and 15.9 is under 20amps with 20amps being enough headroom to provide adequate protection but keep from needlessly blowing fuses.

Now knowing we need at least a 20amp circuit to power those lights we can determine the wire size based on the distance needed to be run using a wire chart. Wire size chart.

You can see that at 25ft for a 20A circuit is calling for 10AWG sized wire, and realistically you would want to go to the next size bigger (numerically lower) because it's right on the edge of what a 10AWG can deliver at that distance. That turns that 10AWG into 8AWG which isn't cheep! What you can do is divide that load up into two, or four wires. If you where to run a wire up for each light you would only need to carry 3.9Amps per wire. We will call it 5Amps for easy math. Now by looking at the chart you can see you only need a 18AWG wire to each bulb. That being said it's always a good idea to go one size higher than you need on your wire size upping that to 16AWG.

You will need a 20A water proof fuse holder. (These usually have 14AWG leads on them.)

A spool of 14AWG wire. (See fuse holder above for why)

A pack of 16-14AWG butt connectors.
A pack of 16-14AWG female push on terminals
A pack of 16-14AWG ring terminals
(I like to use the kind that have the heatshrink tubing built in.)

A standard 30A relay (I prefer to buy the ones with the harness.)

A switch of you're choice.

You can shop around for your items, but I have found that DelCity.net has some hard to beat prices, and hard to find items.

Thank you for the great info! So if I decide to run full-length wires from each light to the relay pins 87, I'll only need 14 gauge wire...I think I'll do that!

 

[xcm]

PERFECT! I think I understand now. Just for my own sake, I am going to write what I see into words for you to verify. I think that picture helped a ton. Alright, here goes:

So from the battery, I'll have to 12 gauge (just for the sake of having a number) wires, each with a 30A fuse holder and fuse in the middle. Those wires are going to pin 30 of their respective relay. Also at pin 30, is a smaller wire going to pin 86. From each pin 87, I'll have 12 gauge wire running up the the lights, spliced into 2 at the top, for a total of 4 wires/lights. From each pin 85, I'll have a smaller gauge wire running to the switch. Also at the switch is a line for a ground, and a line to the fuse box (where on the fuse box?) Each light is also grounded.

Did I get it?

Allmost there! the line that goes to the fuse box, in zj scott's method, is not used in mine, i hate wiring a long hot wire, so i switch the ground side, thats where the short jumper wires that go from pin 30 to 85..


Happy holidays.

 

[bzauche]

Allmost there! the line that goes to the fuse box, in zj scott's method, is not used in mine, i hate wiring a long hot wire, so i switch the ground side, thats where the short jumper wires that go from pin 30 to 85..


Happy holidays.

So the short wire from 30 to 86 (did you mean 86?) eliminates the need for a wire to the fuse box altogether?

 

[xcm]

yup, you need 12v at pin 30(feed), and at 85... sorry.

real easy way to do this, is wire up a light at the workbench with an extra battery! you can hear the relay click.

 

[bzauche]

yup, you need 12v at pin 30(feed), and at 85... sorry.

real easy way to do this, is wire up a light at the workbench with an extra battery! you can hear the relay click.

In your diagram you have a small wire going from pin 30 to pin 86, not pin 85...am I missing something?

 

[xcm]

Thats what you call a typo! mspaint ftl.

It goes to 85, 86 is ground.

It looks more difficult than it is, wire something up on the workbench, it'll turn crystal clear.

 

[bzauche]

Thats what you call a typo! mspaint ftl.

It goes to 85, 86 is ground.

It looks more difficult than it is, wire something up on the workbench, it'll turn crystal clear.

Ah, gotcha. So 30 to 85, then 86 is the ground, not 85. I look forward to being able to start on this project! I will update later with some pictures, hopefully. Thank you so much again for the help!

 

[xcm]

Good luck, you got dis!