Hot Stuff!

Hot Stuff! Ok, while I'm on a winter maintenance kick let me talk about one of the most neglected pieces of gear on your boat, the shorepower cord. Yea, I know who cares right? As long as the TV and the blender are still working that stupid yellow piece of wire really doesn't matter right? Well, how about if I told you that that stupid piece of cable was probably one of the most common causes of fires on and near boats, would that get your attention? Shore cables and dock boxes live a tough life, and neglect will eventually take its toll ...

8th December 2009.
By Ed Sherman

Hot Stuff!

Ok, while I’m on a winter maintenance kick let me talk about one of the most neglected pieces of gear on your boat, the shorepower cord. Yea, I know who cares right? As long as the TV and the blender are still working that stupid yellow piece of wire really doesn’t matter right?

Well, how about if I told you that that stupid piece of cable was probably one of the most common causes of fires on and near boats, would that get your attention?

Shore cables and dock boxes live a tough life, and neglect will eventually take its toll in the form of corrosion and loose electrical connections at one end of the cord or the other, and often both ends.

One of the basic tenants of electricity is that loose connections and corrosion cause excessive electrical resistance. The primary byproduct of electrical resistance is heat…..sometimes enough to catch on fire. The circuit breaker in the dock box won’t help you here because they are not engineered to respond to heat, but rather excessive current flow. Thermal breakers and fuses are used in electrical work, but not generally in this application, so don’t count on the breakers in the dock box to save you here, cause they won’t. The more current your boat is consuming, the more heat a loose connection will generate, and keep in mind that this can happen at either your boat’s end or at the dock end. An excellent example of this heat build up can actually be seen with a thermal imaging camera. The photo below, used by permission from my good friend Kevin Ritz of Cruising Essentials out in Oregon illustrates this beautifully:

Nice glow on that one, and its on the boat side of the cord. Below is a regular photo of the same cord as its plugged into the boat:

Well, looking at the photo of the exact same cord, its pretty hard to tell that trouble is just around the corner, but believe me the thermal imaging camera doesn’t lie. Behind that yellow insulation trouble is lurking. So, the strategy here is to inspect things a little more closely, and a visual inspection is all that’s needed. Shut off the power, or if the cord is hanging up in your garage right now go out and grap it and give it a look see. If any of the terminals look like the ones in the photo below, its time to take action.

What action is needed if you see any evidence of hot running and the resultant melting as seen above? In the case of the female connections, the problem is most likely that the metal contacts in the plug assembly have simply loosened up over time and use and loose connections equal heat. You need to buy a replacement end and install it. Any good marine chandlery will have the part. Make sure you match it exactly, 30 amp, 50 amp, 100 amp. Follow the instructions to the letter so that wires don’t get crossed. If you have doubts about your abilities here, hire an expert to do it for you. I say this with a caveat. If the cord itself is beat to death, which is often the case, spring for a new cord! Its way cheaper than a boat fire…. If the problem is at the dock end, get the marina to act on it quickly, its in their best interest and make sure you make them completely aware of that fact!

Got corrosion issues? Stay tuned for my next several posts as I’m going to be doing a multi-session piece on galvanic corrosion issues that could save you an outdrive or saildrive. Over and out for now!

 


About the author:

Ed Sherman

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Ed Sherman is a regular contributor to boats.com, 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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http://www.EdsBoatTips.com

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