What Wire Size Is Needed For 12 Volt Power On Truck To Operate Interior Lights On Camper

Updated 02/04/2011 | Published 02/02/2011

Products Featured in This Question

Adapter 4-Pole to 7-Pole and 4-Pole

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10 Gauge Wire - Blue Primary - Per Foot

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Adapter 4-Pole to 5-Pole Trailer Wiring Adapter - Shorter

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40 Amp In-Line Circuit Breaker - Perpendicular Mount Bracket

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7-Way Molded Trailer Wire Connector - 3' Long

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Hook Probe Circuit Tester

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Question:

I have a pop up camper the has a flat 4 connector. My truck, also a flat for connector. All lights work fine. I also have a black hot lead on the trailer to operate the inside lights because there is no battery. This wire is currently not connected. I bought Hopkins Wiring - 47515 to use the blue wire as the 12v lead on me truck. I will run the wire into a 40 amp circuit breaker then to the battery. The wire on the trailer is either a 10 or 12ga wire. The question here is what size wire should I use on my truck? I believe the blue wire on Hopkins Wiring - 47515 is 16ga is this bad? Any ideas Thank you

asked by: Chuck

Expert Reply:

The wire gauge of the blue wire on the Hopkins Adapter 4 Pole to 5 Pole Trailer Wiring Adapter, part # 47515, will be too small to be able to use as a 12 volt power source. You will need to use a 10 gauge wire on your truck to run a 12 volt power wire to your trailer connector, along with a 40-amp circuit breaker.

I would recommend to install the Hopkins Adapter 4 Pole to 7 Pole and 4 Pole, part # 37185, on your truck. This Hopkins adapter will plug into your 4-flat connector on your truck and mount on the rear of your vehicle.The four remaining wires will need to be hardwired to the corresponding circuits on the vehicle.

The white (ground) wire will need to be attached to the vehicle frame, the black (12 volt power) wire is connected to the vehicles battery with 10 gauge wire like the # 10-1-1, through a 40-amp circuit breaker # 9510, the blue (trailer brake) wire will be connected to the blue trailer brake feed wire on the brake controller if you have one, and the purple ( auxiliary) wire is for reverse lights if you need that circuit. If any of these connections are not needed just tape them up out of the way for future use.

On your trailer I would replace the 4-flat with the Hopkins 7-Way Molded Trailer Wire Connector, part # H20042. Using a circuit tester like part # PTW2993 I would test the wires on your trailer for the function of each wire and wire to the Hopkins adapter accordingly.

The black wire on the adapter would be for your 12-volt power, the yellow wire can be used for any other auxiliary use like reverse lights, and the blue wire would be used for electric brakes. Again, if not all of the wires are to be used they can be taped up out of the way for future use.

With this setup you will have a 7-way on both the vehicle and the camper which will allow you to be able to add other connections in the future without having to do more wiring.

I am including a link to a FAQ page on trailer wiring.