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How to Establish Ground Connection When Re-Wiring Aluminum Trailer  


I am planning to use the Hopkins 7-way pigtail connecting to a trailer junction box to be mounted inside the coach. Also using the 10-2-1 for the brakes and the bonded 4wire for running lights. My question has to do with grounding. The white from the pigtail is attached to the junction box and then grounded to the steel frame. The 4wire running to the rear of the trailer inside also has a white ground wire. Do you suggest a grounding bar at the rear with common/ground for all rear lights running to that or white wire grounded to frame at rear and lights grounded to body aluminum? or something else? Also for the side marker lights attached to brown in separate run same question. Ground to chassis or lead back to ground bar? Thanks for you help


Helpful Expert Reply:

Aluminum trailer frames or bodies can cause grounding issues so I suggest using a separate ground wire that runs from the rear of the trailer up to the main ground post in the junction box like # 38656. You can join the ground wires for the individual lights at the rear of the trailer to one length of 10-gauge wire # 10-1-1 that can connect at the junction box. This way all trailer light grounds will be referenced to the main vehicle ground, which also connects to the junction box.

You may prefer to use Jacketed 7-Wire cable # DW04914-1. This includes a 10-gauge white ground wire as compared to the bonded 4-pole wire you referenced # 16-4B-1 which has only a 16-gauge ground wire. Plus it will be better protected from weather and road hazards.

You'll need ring terminals like # 44-5310A and you can use dielectric grease # 11755 to keep those connections free of corrosion.

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