Adding an In Line Fuse to a 12 V Power Lead from a Vehicle Battery to a Trailer Connector

Updated 08/17/2012 | Published 08/14/2012

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Question:

what size in line fuse should i use on a fused battery lead to a small pop up trailer with 30 amp service plug two 15 anp circuits?

asked by: Larry R

Expert Reply:

I assume you are wanting to add an in line fuse to a 12V power circuit running from your vehicle battery to the trailer connector on your vehicle. There are a few things to consider before adding an in line fuse to a 12V power lead to a trailer connector.

If your vehicle currently has a factory installed 7-way trailer connector, then the power lead will already have a fuse.

If you are adding a 12V power lead to your vehicle, then we typically require a 40 amp circuit breaker, like part # PK54540, or a 40 amp in line fuse. If your trailer is only rated at 30 amps, then you could just add a 30 amp circuit breaker, like part # PK54530, or a 30 amp in line fuse with a properly rated fuse holder.

I would recommend adding one of the circuit breakers that I mentioned rather than an in line fuse because the circuit breaker will automatically reset itself in the event that the circuit is overloaded.

I have attached a help article on routing a power wire for a trailer wiring harness for you to check out.

expert reply by: John H