How To Install LED Light Bar - lightbarreport How to Install LED Light Bar Wiring. A more complete guide to LED light bar wiring is here, but the general steps are these: Always disconnect the negative terminal of your battery before starting the wiring. Use automotive grade wire. GPT is acceptable, but GTX and TLX grades are better. Use a wire gauge that matches or exceeds the maximum5/5(1)[PDF] LED Light Bar,Wiring Instructions - Summit Racing Equipment Installation Instructions L.E.D. Light Bar (Part #’s 76204, 76208,76212, 76220,76231,76238,76246) L.E.D. Light Bar Wiring Kit (Part# 76200) 3. Route the harness from the mounted switch to the battery and to the LED light bar. (If drilling through firewall be sure to use some kind of grommet so the wires do not rub) WIRE LOOM A.