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Old 11-02-2012, 19:33   #1
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A/C Wiring Short ?

Hi Everyone
I new here and happy to be aboard!

O.K. My question if anyone can help?

In the process of trying track down stray electrical current I put my ohm meter between the hot and neutral on one of my ac outlets. The shore power was off as well as the breaker for the outlets. The ohm meter(s) read a short. (low ohm reading, closed line, the meter beeps the same as when you put the ends together). I am sure this is not right but need reassurance as the breaker is not tripping, the wires aren't hot and a clamp amp meter is telling me i am not drawing more current than i should be.

am I totally missing something or do i have a short that is not breaking the breaker and some how going to ground or something? The reading from both hot and neutral to ground is infinite ohms.

Thanks.
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Old 11-02-2012, 19:41   #2
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What was the last electrical install or modification done?
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Old 11-02-2012, 19:49   #3
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Re: A/C Wiring Short?

None. I bought the boat in August and have been slowly servicing, upgrading and repairing systems but I have not touched the A/C until today when i noticed the zink on my prop shaft was deteriorating. I started the process of finding any stay current to ground and immediately found this problem.
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Old 11-02-2012, 19:53   #4
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Re: A/C Wiring Short?

Stray strand? I'd pull out all the outlets and have a look.

Worn/bare insulation in one of the feeder pairs?

Note: lightbulbs and motors and similar loads on the circuit could show a low ohm reading as well. Be sure there are none and/or they are switched off.

You definitely should not have continuity between the hot and neutral wires with the breaker turned off.

If it were on and you had an isolation transformer, that would be different, but with it OFF there should be no connection whatsoever.

Bill
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Old 11-02-2012, 20:14   #5
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Re: A/C Wiring Short?

Thanks, I think that's what it must be too. Appreciate the reassurance.
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Old 11-02-2012, 20:23   #6
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Re: A/C Wiring Short?

More than likely you have an appliance or something else plugged into the line somewhere up or downstream from where you are measuring. A plugged in appliance/light/?? will show extremely low ohm reading and in some cases it looks like a short - but it is not.

You have to be sure that every outlet, etc. in that power line has everything plugged into it disconnected/removed before you can make any measurements.
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Old 12-02-2012, 05:46   #7
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Re: A/C Wiring Short?

Quote:
Originally Posted by osirissail View Post
More than likely you have an appliance or something else plugged into the line ...
Indeed.

Greetings and welcome aboard the CF, kyuquot.
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Old 12-02-2012, 05:51   #8
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Re: A/C Wiring Short?

Quote:
Originally Posted by kyuquot View Post
Hi Everyone
I new here and happy to be aboard!

O.K. My question if anyone can help?

Thanks.
Are you sure no other users are connected to the circuit?
Oops; I should have read on before I opened my mouth.
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Old 12-02-2012, 09:01   #9
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Do you have ground fault outlets?
Is boat out of water (anode deterioration) ?
Since you just bought boat do you know if everything is on a common ground?
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Old 12-02-2012, 10:47   #10
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Re: A/C Wiring Short?

Thanks for the replies.

There is a common ground, whether everything is on it I will determine today.

There are only 3 appliances's on the ac. The Invert/charger (wired before the main ac breaker/disconnect), HWT, and outlets. I have unplugged all appliances's from the outlets but will double check.

I was able to separate (and disconnect) the port/starboard wire runs suppling the outlets. It looks like the Starboard side is good and the short is in the port wire run. At least I have narrowed it down. The problem now is that the "feeder pairs" are only 2 conductor (+green ground) to the outlet. This means i can't easily break the circuit to isolate the short. In other words the feeder pairs have been crimp connected to the wire run inside the wire bundle (instead of at the outlet j box) that is run through conduit and very difficult to get at.

Any ideas on how to further isolate the short in this situation??

Hopefully i have missed something that is plugged in!!!!
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Old 12-02-2012, 11:10   #11
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Re: A/C Wiring Short?

Nibiruwayne,

The boat is in the water. I can see the propeler and zinc.
They are not gfci outlets. Should they be? Pre-purchase survey didn't mention it but i have thought about it.
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Old 12-02-2012, 11:39   #12
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Re: A/C Wiring Short?

HWT....hot water tank? If the hot water heater is connected, it's breaker on, and its thermostat tripped (to draw current) that would do it. Essentially a big resistor between the hot and neutral lines.

Bill
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Old 12-02-2012, 11:51   #13
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Re: A/C Wiring Short?

What happens when the Power is on?
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Old 12-02-2012, 14:48   #14
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Re: A/C Wiring Short?

"In other words the feeder pairs have been crimp connected to the wire run inside the wire bundle (instead of at the outlet j box) "

I'm going to suggest that that would violate most electrical codes if done on land, and it is the sign of a homebrew job on a boat. We make AC connections inside of boxes as extra protection against wiring problems, and if you have any reason to think the AC wiring was not done 100% correctly...It might be simpler and safer to remove it all and rewire it.

Among other things there should be a double breaker on the AC main panel, and a GFI (whatever you prefer to call it) as close to the AC feed into the boat as possible. If you don't see these things--consider rewiring from scratch, instead of banging your head trying to figure out what the last guy did.
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Old 12-02-2012, 19:09   #15
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If you do rewire, consider GFI outlets everywhere. Better to have them trip a 5 MA than trying to kick a breaker if you should get across the hot. GFI outlets are not much money when you consider their safety value.

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