120 volt reversed hot and neutral can this cause severe electrolysis - SailNet Community

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post #1 of 31 Old 01-02-2009 Thread Starter
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120 volt reversed hot and neutral can this cause severe electrolysis

I was having some issues with electrolysis on my sailboat so I installed a galvanic isolator with a led monitor and turned it on and it said I had no problems with the ground( no leds on ) . so the other day I shut off all my breakers on the boat to replace my leaking water heater I started to remove the wires and they were still hot so I unplugged shoreline . I replaced the
water heater and every thing was fine,but I still wondered why my wiring was hot when I turned off all breakers. I went to the hardware store and purchased a receptacle tester and found my hot and neutral were reversed so I started at the marina plug and guess what the hot and neutral were reversed, so that is fixed. My question is with the hot and neutral reversed at the marina side
would this be causing my electrolysis problem? Thanks Mark
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post #2 of 31 Old 01-02-2009
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I would wonder about the power still on after the breaker is off. Its hooked to something. Yeah, I like that tester to check out the marina wiring. If your post was wrong, what else is wrong. I dont know how many electric cords I have pulled out of the water. People just unhook there boat and throw it on the dock hot and expect it to stay there.

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post #3 of 31 Old 01-02-2009
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I agree with badsanta. If you shut off all the breakers and the system is still hot you have a serious problem. Convential wisdom until recently has always been that galvanic corrosion is a DC problem, but some recent studies have shown that stray AC may also cause it. But worse yet, stray AC will kill you. You need to get this fixed. The marina needs to have their dock system checked out thoroughly. You need to make sure the polarity is correct on your boat. And you need to check out those breakers to see that they are working correctly. One last thing. when you unplug the shore power cord, unplug BOTH ends. Then you know for sure it's dead!

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post #4 of 31 Old 01-02-2009
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Don't swim around that ship.
When we move or limbs, we are operating at a few milli-volts.
120 V AC will paralyse you and it will be horrible.
It is the principle of electro-fishing and it is very effective.
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post #5 of 31 Old 01-02-2009 Thread Starter
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I have fixed the the marina shore power and the breakers are working fine and I have checked every plug receptacle and all is ok, I just need to know if that was what was causing my outdrive to be eaten away Thanks Mark
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post #6 of 31 Old 01-02-2009
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Quote:
Originally Posted by lmddmc View Post
I was having some issues with electrolysis on my sailboat so I installed a galvanic isolator with a led monitor and turned it on and it said I had no problems with the ground( no leds on ) . so the other day I shut off all my breakers on the boat to replace my leaking water heater I started to remove the wires and they were still hot so I unplugged shoreline . I replaced the water heater and every thing was fine,but I still wondered why my wiring was hot when I turned off all breakers.
If you've turned off the main shorepower breaker, NONE OF THE AC WIRES, other than the ones between the AC panel and the shore power inlet should be hot.

If any still were hot, YOU HAVE A PROBLEM.


The MAIN AC PANEL on a boat should have TWO BREAKERS for the shorepower connection—one for hot and one for neutral. If yours doesn't have a double breaker on the SHOREPOWER FEED to the AC PANEL—you need to fix that. The reason for the two breakers is to prevent the boat's internal AC wiring from being energized in the case of a reverse polarity problem on the shorepower post. Not fixing this may get someone killed.

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I went to the hardware store and purchased a receptacle tester and found my hot and neutral were reversed so I started at the marina plug and guess what the hot and neutral were reversed, so that is fixed. My question is with the hot and neutral reversed at the marina side
would this be causing my electrolysis problem? Thanks Mark
It is possible, but there could also be so many other problems with this electrical system, it can't really be determined from what you've said.

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post #7 of 31 Old 01-02-2009
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The problem was reversed polarity at the marina receptacle and IMDDMC clearly states in his post that this problem has been fixed. Come-on people read the posts. I will agree with Dawg that the main should be a double pole breaker, disconnecting the neutral and hot when "off".
The elctrolysis is caused through the gound wire so reversing polarity will not effect it.
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post #8 of 31 Old 01-02-2009
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Ebs-

If he had all the breakers on his boat off, and was still getting live AC at the hot water heater, his AC panel design has a serious flaw. The electrolysis issue is far less important IMHO, since that won't generally kill you stone cold dead—a bad AC panel design will.

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post #9 of 31 Old 01-02-2009
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Dawg read the 1st post. With reverse polarity at the marina plug his breakers were switching the neutrals so he would still have power on the hots. The only "design flaw" is that he appears to have only a single pole main breaker when it should be a double pole. The reverse polarity problem was repaired and he verified that his receptacles are proplerly wired with the tester. He did not indicate whether the main was a single pole or a double pole but I agreed with you it should be a double pole switching the hot and the neutral.
Salt water marinas are notoriously bad for stray currents and a galvanic isolator is really his solution for that problem.
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post #10 of 31 Old 01-02-2009
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Mark, you indicate your problem is fixed but I suggest you read this Electrolysis as it may prove helpful to you regarding your question about electrolysis.

The simple answer to your only question is yes.

ebs I am having difficulty in understanding how the circuit is being completed if all the breakers are off, even if they are single pole breakers. If the polarity is reversed, then when the breaker is off, the wire acting as the neutral would be open. The only other conductor left would be the ground to carry the current, which in essence would be a direct short causing a breaker to trip someplace. What am I missing? Or do you think the current from the water heater is going to ground in the sea and not using the grounding conductor?
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