This is a guide on how to wire an LED light bar without a relay.
If you are wiring an LED light bar/off-road light from scratch you may want to avoid the hassle of connecting a relay as well when you install it. Since LED light bars are essentially their own circuit a relay is used to safely operate that circuit using the circuit connected to your power source.
However, this is not strictly necessary in all cases and it can be safe to wire a light bar without a relay as long as you check your current specifications.
That is why this article provides you with the information to determine if it is safe to do so. Furthermore, it includes steps required to install the light bar without a relay.
If you have not yet purchased a Light bar, have a look at our review of the best LED light bars for the money.
What is a Relay?
A relay is an electromagnetic switch that can open and close circuits (or switch between circuits). The switch is made up of an electrical coil that becomes magnetized when current is passed through it. This will magnetically pull a switch into a closed position.
Relays act as a bridge between high-powered circuits and low current circuits so that a low-powered circuit can control the power to a high-powered circuit. A relay protects the low-powered circuit from receiving too much current and damaging the wire and other electrical components in that circuit.
Therefore, in the context of wiring an LED light bar, you can think of the high-powered circuit as the light bar and the electrical circuit of your vehicle, as the low-powered circuit (generally around 12V DC). This is because LED light bars are designed as their own electrical circuit and depending on the amount of LED’s, watts, etc. that circuit will draw a specific amount of amps.
This leads us to the next question:
Do LED Light Bars Need a Relay?
The short answer is No…not always…it depends…
Depends on what exactly?
Well, it depends on how much current your light bar is going to draw. Basically, how many amps will it try to pull from the circuit?
If it is trying to pull more current than the circuit can handle, you can damage that circuit. So, your wire can melt and your switches can burn out.
This applies to all the components attached to the circuit. Therefore, If you are not connecting your light bar directly to your battery, you should use a relay to protect the rest of the circuit.
How to Determine if it is Safe to Wire Your LED light bar Without a Relay
Before you proceed with the wiring, you need to determine whether it is safe to do so.
The following are the key pieces of information to find out to determine whether you can safely proceed without a relay:
- Light bar amps
- Wire gauge
- fuse amps
- Switch amp maximum
Light Bar Amps
This refers to how many amps your light bar going to draw.
This is the most important piece of information you need to work out. The reason is that it will inform every one of the following safety checks. You can also use this information to purchase the following items that can handle the correct current for your LED light bar.
You may find this information on the list of included specifications for your light bar but if not you can work it out using the following equation:
| Amps = Watts/Volts Therefore, if your vehicle has a 12V battery and the Light bar is 300 watts then: Amps = 300/12; Therefore, Amps = 25; |
So, if the light bar is going to draw 25 amps of current, your circuit needs to be able to handle that amount of current. This leads us to the next point:
Wire gauge
Your wire gauge, or simply how thick your wire is, will determine how much current it can withstand.
This chart will help you determine what gauge your wire needs to be depending on the current (amperage) and distance (how long the length of wire needs to be).
Fuse and Switch
Both of these components need to be matched up with the current draw from your lightbar. So, if we keep using our example from above, your fuse needs to withstand higher than 25 in order to provide protection when the draw exceeds that amount.
Furthermore, you need to check your switch or purchase a switch that can handle the current.
Safest Way to Wire an LED Light Bar Without a Relay
Below is the safest way:
Wire the light bar directly to the battery!
Assuming all the above requirements are met (or you have purchased the right components based on the Light bars current), the safest way to wire your light bar without a relay is to connect the circuit straight to the battery.
That way you only need to worry about the rest of your car’s circuit components and whether they can handle the current draw.
The downside to this approach is that your light will have to be switched off using a separate switch as you will not be able to wire it so that it turns on with your ignition.
Light Bar Wiring Diagram Without Relay
Before we dive into the exact steps. This simplified lighting diagram will provide a visual overview to make the following step much easier to understand.
This diagram makes it very easy to understand how to wire up your LED light bar:
Now that we have this above visual we can get into the exact steps for wiring this up below:
How to Wire LED Light Bar Without Relay: 5 Steps
Accessories you may need:
- Fuse Holder
- Pigtail connector (depends on the female connector on your light bar)
- Switch
- Wire (be sure to choose the appropriate gauge)
- Wire nuts/connectors
Now that you have everything you need, let’s get into the exact steps:
1. Determine light bar and switch mount locations
Select an appropriate location for your light bar and loosely mount it by drilling the necessary holes and using the hardware provided. Do not fully tighten at this stage.
Once you have determined a location for your switch, you will likely need to drill a hole or cut-out in order to fit your switch and secure it. However, you should not secure your switch just yet.
2. Route your wires
Run your negative (black) and positive (red) wiring between each location. Do not connect anything at this point.
You will need to run your negative, black wire from the battery to your light bar. Your light bar may have some sort of female connector, in which case you may need to purchase a corresponding male connecter. You will then connect the black wire to the corresponding black wire on the male connector.
Your positive red wire will need to run the length from your positive battery terminal to a fuse Holder (with fuse installed), to your switch location, and finally to your light bar. You will need to separate your wire at each location according to this path:
Battery > Wire length 1 > Fuse > Wire length 2> Wire length 3 > Switch > Wire length 4 > Light bar.
Overall, when routing the wires, avoid heat sources and follow a safe route like your vehicle’s wire harness.
Notes:
- You may need a male pigtail adaptor to fit the socket connected to your light bar
- You can use a remote-controlled switch to keep all wiring under your hood.
- Fuse should be installed within 18 inches of the battery
3. Mount switch
Drill the appropriate holes or cut-out in order to mount your switch and secure it in place.
4. Connect your wires
Connect your black wire to your battery and light bar.
Connect red wires between the battery fuse and switch input. Then connect the switch output and the Light bar.
5. Secure all mounting and make sure everything is functioning
Now, everything should be connected so you can secure your LED light bar by tightening the hardware. The last thing you need to do is make sure everything is working and your light turn on and off with the switch.
Congratulations, you have successfully wired an LED light bar without a relay.
Alternative Solutions (Easy and Safe)
There are also a few alternative options to make your life easier. These include buying a wiring harness that already includes a relay or making your own harness with a relay.
Click on the links below if you are interested in either of these options:
Installation Using a Wiring Harness
If you are looking to wire your LED light bar with a relay you can check out the following videos:
Final Thoughts
So, by now you should be able to safely wire an LED light bar without a relay or at least determine if you can safely do so with your LED light bar setup.
The broad steps have been included as well as tools and diagrams that will aid the process.
Furthermore, alternative options have been provided to wire your LED light bar with a relay but without the hassle.
It is always recommended you do use a relay, in which case the above alternative solutions should come in handy if you decide to go that route.