Trailer Wiring Gauge Recommendation for Installing Brake Controller

Question:

I seen different answers for the same type of questions. With the P3 use on GM products Ive seen on answer use 12 gauge wire and another answer use 10 gauge wire. If you use the 10 gauge and the controller is 12 gauge and you run 10 gauge wire for 20 feet and then connect again to 12 gauge on the 7 blade male end. What is the right gauge? Also, I seem two different instructions on connecting on the 7 blade connector. One says remove the wire connected in the connector and another says cut the wire 5 to 6 inches before connector. What is the correct answer?

asked by: Elden P

Expert Reply:

Ideally you run 10 guage like part # 10-1-1 as it's the heavier and will guarantee the circuit can carry the amperage. There are plenty of situations where 12 gauge will be fine like part # 12-1-1 but if the trailer has several sets of brake axles and the wiring ends up being longer than usual the 10 gauge provides a bit of a safety net. Basically the longer the wire the more resistance so going heavier than needed can compensate for that.

As far as making the connection to the 7-way your best option is to attach it directly to the 7-way's brake output circuit which is the 5:00 position.

expert reply by: Jameson C