Logo

eletrical woes

leokow

Regular Contributor
Hoping I can get a little direction from those that know a more about boat electrical systems than I do, plus my age isn,t helping me at this stage. I've got to give a little background first, hoping it'll make it easier for anyone to follow along. First of all let me describe the boat. It's a 31.9 Boston Whaler with twin 6.0 375 hp inboards. It has a galley and shore power connections. Last September my wife noticed that the front burner on the electric stove was hot, naturally I disagreed with her saying the breaker is off so it couldn't be. Well. she was right, although I still can't figure out how. anyway when she tried to move the stove there was a good sized spark from the control switch. I cut the shore power and removed the stove completely. Since that time whenever I hook up to shore power to charge the batteries or run the a/c the main pops instantly. I thought that maybe some damage had been done to the 30 amp main when the stove shorted like it did so I replaced it with the same type breaker. This did not fix the problem. I have since removed all connections from the A/C panel except for the battery charger, which I am going to remove next. With the shore power plugged in you can turn on the main and all is fine , the instant you energize any other breaker the main pops almost simultaneously. I must get this fixed before launch this spring , even if it means rewiring the entire A/C portion of the panel. So all of you guys out there that love hair pulling problems please give me a hand and see if we can get somewhere with this. I'll post again with more results after I disconnect the auto charger. Thank you ...Leo
 
based on your description, it seems the wiring to the stove appears to be getting excited from a path the bypasses the stove's circuit breaker.

I think a good inspection would be the best place to start....and then some measurements....what you are describing is a pretty blatant fault - the fun on boats is usually locating that fault...
 
Thanks Mark, what you said is kind of in the same direction I was thinking. I've disconnected any wiring between the breaker and the stove and have come to the conclusion that a short must be occuring within one of the bundles, so I would guess I am at the point where either I open up everything and inspect each leg or I disconnect connection and rewire the individual legs and by pass all of the old wiring. This is the fun part I guess you were refering to. I'll get back when and if I find anything strange.
 
Yes, on the fun part...

If you disconnect the feeds from the panel and You have an idea which cables are run together, sometimes you can get lucky finding shorts with an ohm meter....

When its time to replace, make sure you use a marine grade of wire....may be cheaper to buy it over the net nowadays....and use the proper connectors and tools....

good luck
 
I am by no means a qualified electrician, but if you haven't made any changes to the AC electrical system of your boat, I would start by checking if the AC is being delivered correctly to the shore power outlet that your power cord connects to.

Here in the northwest, there are quite a few floating homes, floating boat sheds and so forth. My Dad had a boat shed with electricity. One day we were going to add a 110v outlet to make it more convenient. We shut off the breaker, but when we opened up the box containing the outlet we were going to extend from, we got a nice fat spark. One of the neighbors had apparently incorrectly wired their main breaker box.

In your case, I would start by asking the marina, or whoever owns the shore power outlet that you plug into, to check it to see if the power is being supplied correctly.
 
Since you have all the load wires disconnected from the AC panel, except for the charger, with the power completely off and unplugged from shore power, take a continuity tester from each load wire one at a time to the AC ground bus at the panel. There shouldn't be any continuity. If you find that there is continuity between any or some of the load wires to ground, that would cause the dead short condition that you have described. If you haven't located the fault, try seeing if there is continuity between the hot bus of the panel to the ground bus. Again with the power completely off.

Good luck.
 
Back
Top