The electrical system is where corners should never be cut. A light bar must never be wired directly to the battery or an existing circuit. It requires a dedicated, fused circuit with a relay. The industry-standard setup uses a relay harness. Connect the thick power wire (typically red) with an in-line fuse (size per light bar specs) directly to the battery’s positive terminal. Connect the thick ground wire (black) to a clean, unpainted metal surface on the chassis or directly to the battery negative. The relay acts as a heavy-duty switch; a small, low-current signal from your cockpit switch will trigger it to send high-current power from the battery to the light bar. This protects your factory wiring and switches. Route the wiring harness through the engine bay carefully, using split loom tubing and zip ties to secure it away from hot engine components, sharp edges, and moving parts like the steering shaft. For a roof-mounted bar, the cable must pass from the body into the cabin. Use an existing factory firewall grommet or a dedicated, sealed weatherproof passthrough to maintain the Jeep’s weather sealing.
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