How to Install a 50 Inch Light Bar? | Mount, Wire, Test

A 50-inch light bar installs in five phases: secure mounting, relay-harness wiring, a battery-side fuse, a cab switch, and final beam aiming.

A 50-inch light bar is one of the easiest big accessories you can bolt onto a truck, UTV, or SUV — but only when you wire it in the right order. Once you see how to install a 50 inch light bar as five fixed jobs — mount, wire, fuse, switch, and aim — the whole project fits into one afternoon with basic hand tools.

That order comes straight from the install guides that ship with real kits. Polaris’s XPEDITION lightbar documentation starts by telling owners to pull the key and disconnect the battery; Hyperion’s instruction manual has you bench-test the bar before it ever reaches the roof. The pattern holds whether the bar is going on a Jeep, a Polaris, or a work truck.

What Do You Need Before Installing A 50-Inch Bar?

You need four things: the bar, a mount that fits your vehicle, a relay wiring harness, and standard hand tools. The bracket is the part most people get wrong, because “universal” fit often is not a real fit.

• A vehicle-specific mount, when one exists. A mount made for the Jeep JL/JT accepts any standard 50-inch LED light bar using factory hardware and no drilling. Universal overhead mounts work for other trucks, but a model-specific bracket gives the cleanest fit on platforms like the Polaris XPEDITION.
• A relay harness, not bare wire. A 50-inch bar draws roughly 20 amps at full brightness, which is more than a cab switch should carry. The relay harness bundles a 40A relay, an inline fuse holder, a waterproof Deutsch-style connector, and the switch wiring.
• The right power wire. Plan on 12 AWG for power and ground, a 25–30A inline fuse, and the fuse placed within 18 inches of battery positive.
• A safe work setup. You need level ground and time to disconnect the battery before any electrical work starts.

Still choosing gear? The best 50-inch light bars we’ve tested are ranked partly by how complete their mounting hardware is.

Mount And Wire In The Order That Works

From a sealed box to a working bar, the job runs in eight steps. Stick to the sequence and you will not be redoing half of it.

1. Disconnect the battery first. On vehicles with factory kits, the documented order is clear: park on level ground, shift into PARK, remove the key, and disconnect the battery. Polaris’s XPEDITION 50-inch Lightbar Kit instructions spell this out before any other step, and the same logic applies to any vehicle.
2. Confirm the mount location. A roof rack or bumper works only if the bar does not block the driver’s view, airflow, or the sensors behind the grille and roof line.
3. Assemble the bracket hardware while the bar is still off the vehicle, then set the bar in place. Leave the bolts snug rather than torqued — final tightening comes after aiming.
4. Route the harness from the mounting point toward the battery along the frame, away from exhaust heat, sharp metal edges, and moving parts. Use the factory wiring channels where you can and secure everything with zip ties.
5. Connect the bar to the harness using the Deutsch plug or the equivalent waterproof connector. If you can bench-test the bar before vehicle installation, do it now.
6. Wire the power side. Connect the harness positive lead to battery positive and the negative lead to the battery negative or a solid chassis ground. Install the inline fuse as close to battery positive as possible.
7. Run the switch circuit through the relay so the cab switch only triggers the relay instead of carrying the full 20-amp load.
8. Test, then aim and tighten. Reconnect the battery, confirm every function works, tilt the bar to the beam angle you want, then torque the hardware.

Here are the electrical numbers worth remembering:

Mistakes That Force A Second Install

Nearly every failed install traces back to six avoidable mistakes. Each one costs the same thing: another afternoon with the hood open.

• Skipping the battery disconnect before touching wiring.
• Mounting where the bar blocks a sensor, the windshield view, or the grille airflow.
• Leaving out the fuse, or placing it far from the battery.
• Routing the harness near heat, pinch points, or spinning parts.
• Tightening the brackets before the beam angle is set.
• Assuming every 50-inch bar fits every vehicle — many need specific bracket geometry.

Road legality is a separate question. The sources that document these installs treat light bars as off-road and vehicle accessories, so confirm your state and local rules before using the bar on public roads.

That is the whole sequence: disconnect the battery, mount loosely, route the harness clear of heat, wire through a 40A relay with a 25–30A fuse within 18 inches of positive, test, then aim and torque. Do those five jobs in that order, and the bar will still be working long after the novelty wears off.

FAQs

Do I need a relay for a 50 inch light bar?

Yes. A 50-inch LED bar pulls roughly 20 amps at full brightness, and most factory switches are not built for that load. A 40A relay solves the problem: the cab switch energizes the relay coil while the heavy current travels on dedicated 12 AWG wire from the battery, protected by a 25–30A inline fuse positioned within 18 inches of the positive terminal.

Can a 50 inch light bar be installed without drilling?

Often, but it depends on the vehicle. A mount built for the Jeep JL/JT accepts any standard 50-inch LED bar using factory hardware, with no drilling required. Universal overhead mounts exist, but they usually mean drilling into the roof or bumper, so a model-specific bracket is the cleaner path on vehicles like the Polaris XPEDITION.

Can I run a 50 inch light bar on public roads?

That depends on state and local law, and light-bar manufacturers generally market these bars for off-road and trail use rather than street driving. Polaris’s documentation treats its XPEDITION lightbar as an off-road accessory, so confirm your jurisdiction’s rules before using the bar on pavement. When in doubt, keep it for the trail.