Marine Wiring: No Mess, No Wire Nuts

A messy installation with lubberly wire nuts may work for the time being, but you are asking for trouble in the long run -- and maybe not so long.

7th May 2013.
By Ed Sherman

Question: I just had my boat surveyed to determine the value for insurance purposes. The surveyor really slammed my electrical system, saying that I needed to hire a qualified marine electrician ASAP to bring the wiring into compliance with ABYC standards. He included the picture I sent in as an example of some of the issues.

wiring mess with wire nuts

Yellow arrows indicate wire nuts, a very bad idea to use on a boat, especially on stranded wire.

The yellow arrows are pointing to wire nuts, which he says are not allowed. What’s the real story here? Is this guy just trying to make my life tough? Everything works on my boat and I really don’t feel a need to do anything.

Answer: I’m on your surveyor’s side with this. The photo you sent in is an all too common example of how not to do things electrically. Even though all your electrical equipment might be working OK right now, the condition of the wiring installation you are showing me in your photo tells me that trouble is lurking on your boat just behind the scenes.

First, the wire nuts you point out. Understand that marine wiring requires the use of multi-stranded wires throughout. Those wire nuts are engineered for use with single-strand solid copper wire as used in land-based applications. They have coiled metal inserts inside and are designed to be screwed onto a pair of wires that have been twisted together. With stranded conductors, the more the installer twists the wire nut into place, the more small strands of wire get damaged. The bottom line here is a wire termination that is doomed to premature failure. Wire nuts have no place on a boat.

Unfortunately your electrical issues don’t stop with the wire nuts. The unsupported cables and helter-skelter collection of wires you show in the photo show a general disregard for compliance with a variety of ABYC electrical standards. Everything may be functioning on your boat at the moment, but with the sort of installation you present here, I can assure you that in the long haul, problems will be plentiful.

Your surveyor is right on in this case. Call a good marine electrician ASAP, preferably an ABYC-certified marine electrician.

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About the author:

Ed Sherman

Ed Sherman is a regular contributor to, as well as to Professional Boatbuilder and Cruising World, where he previously was electronics editor. He also is the curriculum director for the American Boat and Yacht Council. Previously, Ed was chairman of the Marine Technology Department at the New England Institute of Technology. Ed’s blog posts appear courtesy of his website, EdsBoatTips.

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