2 electrical questions - breakers and GFI

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Jun 25, 2005
73
Hunter 25_73-83 St. Clair Shores
I consulted a couple books and want to see if I can get some clarification. In reading Casey's book he mentioned to have a circuit breaker installed very close to the actual AC outlet on the boat (where you connect to shore power). I am almost positive the AC main switch panel I have has a circuit breaker built-in, but according to the book, the closer to the source of the power (further up the "main power" leg) the quicker it will shut power off in the event of an "episode", thus being much safer. My power outlet is in the cockpit area essentially under the coaming. Should I insall a circuit breaker right beside the outlet? Question two: In regards to installing a GFI outlet. My boat (a 77' H25) does not have any, and the books mention you only need one GFI outlet - typically on the outlet closest to the AC panel. I have a total of 3 outlets on the boat, and all are dedicated wire runs from the AC switch panel to the outlet. In my novice view, it does not seem like the GFI outlet would trip to protect me, if I was using a device on a seperate outlet with it's own switch on the AC panel.....right? At $10 ea. I guess I could just buy 3 GFI outlets and be cautious. Do you need to buy Marine outlets, or will Home Depot GFI outlets suffice? Many thanks!!!
 
Dec 2, 2003
1,637
Hunter 376 Warsash, England --
Outlets or Inlets?

I think you may be referring to AC inlets - i.e. where shore power comes into the boat. The concept of placing the circuit breaker as close as possible to the inlet socket is to minimise the length of vulnerable wire on board. This is not for speed of response but rather to get maximum protection in the event of damage to the boat wiring causing electric shock or fire. Ref GFI (or RCD or ELCB) - all mean the same device, you only need one per INLET socket. Again best nearest to the inlet socket(s) for the above reasons. Also most marinas will already have protection at the point you plug in to their supply so, unless you hook up to non marina supplies you do not need GFI - though its nice to have it anyway. Does no harm and is 'belts & braces'. Remember however you will need access to breakers and GFI devices to reset them in the event of a trip. As long as the location for these items is DRY and will remain so, then domestic types should be okay. Please note mains AC is dangerous so, unless you are fully confident in everything you do, get an electrician to do or oversee the job. You owe this to your crew as well. Good luck. PS:- Do you really need 3 inlets? Are you a heavy power user? Must look like spaghetti when you connect up.
 
T

Tim Musolf

circuit breakers and gfci's

I believe that Casey reccomends a circuit breaker as close to the shore power connection as possible to protect the wire to the AC panel. If the breaker is in the AC panel some distance from the shorepower connection you are relying on the circuit breaker on the dock to protect the wire inside the boat up to the AC panel. You don't know what the condition of the breaker is and may not know the amperage rating.The breaker on the dock may not clear a fault occuring in the wire between it and the AC panel. As to your second question about a gfci, you may only need one gfci outlet as long as the gfci is wired as the first outlet and all the others are wired on the load side of the gfci.It sounds like your panel is wired with each outlet having a separate wire going to it. in this case you will need a gfci at each outlet. This is still very cheap protection as you mention. Also remember that in order to work properly you must have a good ground connected to each gfci. Hope this helps.
 
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