Water heater popping GFCI

[jetdrvr393]

On our new to us Cat 30 the hot water heater is popping the GFCI it is plugged into to. It's an Emerson instant water heater that is not designed to be on a boat (that I know of). Everything else on the circuit works fine and doesn't trip it. Everything worked fine at the dock it used to be at and now that we have it home it keeps tripping it. My question is, could the shore power at our marina have less amps than at the old one and could this cause it?
I have done nothing whatsoever to the hot water heater since it used to work and now it doesn't.
Should I pull it out just because it's not designed for a boat or does it not matter? (were fresh water)

[ebs001]

A GFCI only trips on a fault to ground not an overload. If other items plugged into the GFCI do not trip the GFCI then there is a fault in your hot water heater. Because a GFCI will trip on as little as 5 milleamps it's not so easy to find. A GFCI measures the current on the hot versus the current on the nuetral and if they differ it trips. First thing to do is check connections in the heater paying particular attention to the neutral because the fault is on the neutral side. Next check to see if there is continuity between the nuetral connection and ground. The unit must be unplugged to do this. If you have continuity to ground your element needs replacing.

[saillife]

First off I totally agree with ebs001.

At your local Lowes or Home Depot you can buy a tester that looks like one of those old, evil 3 - 2 prong adapters that will test GFCI plugs. Has three lights on the back side to tell you if the plug is wired correctly. Well worth the ten bucks. Get the one with the button that will 'short' the circuit.

To verify that it is you heater. I would take it home and plug it into a gfci at home. If it pops you know it's in the heater.
Good luck
Brian

[jetdrvr393]

The heater just has an electrical cord coming out of it. I think I would have to take it apart to check the neutral. It is also plumbed into the system so taking it out is not a great option, If i do that I will just replace it. I guess the thing that puzzles me is that the last time I had it plugged in it worked fine ( we did not leave it plugged in all the time).
I know that things can break at any time but this just seems weird. The surveyor did check all the GFCI's and they were good at he survey.

[deniseO30]

That type of heater uses high amps to heat the water. I would ck the heater amperage draw plate. I'm guessing it's 120 volt at 15 amps. There could be a short in the heater itself causing the GFCI to pop also. The heater may have been turned on when by chance the water pump was off and the lines had air in them. the element will go poof in very short order if it's not immersed. Does it operate on a non GFCI circuit? I'm betting the heater is shorted, most likely the element.

[ebs001]

Originally Posted by jetdrvr393

The heater just has an electrical cord coming out of it. I think I would have to take it apart to check the neutral. It is also plumbed into the system so taking it out is not a great option, If i do that I will just replace it. I guess the thing that puzzles me is that the last time I had it plugged in it worked fine ( we did not leave it plugged in all the time).
I know that things can break at any time but this just seems weird. The surveyor did check all the GFCI's and they were good at he survey.

You can check continuity to ground at the male cap of the cord coming from the heater - neutral to ground. You can also check to see if the heater element is good at that cord end by checking resistance hot to neutral. While your at it check hot to ground as well. The resistances between ground and neutral and between hot and ground should show an open circuit. The resistance between hot and neutral should be around 8 ohms. The ground is "U" shaped and the neutral is the blade on the right with the ground down and the plug facing you.
Elements go regularily and it can happen at anytime. There is no need for the unit to be plugged in.