The Tank › State Electric, power problems
- October 8, 2008 at 2:07 am #9577OspreyParticipant
Howdy, gang. Facing a persistent lil’ gremlin here that won’t quit.
Recently, our 11yo State HWT began tripping it’s 30A DPDT breaker. Resetting the high limit would allow the breaker to be reset, and the tank would heat up just fine.
Here’s where things began to get wierd. The tank would run fine for hours; sometimes overnight, other times, 24+ hours, before the next reset. Then, back to resetting the high limit and breaker, and repeat the process all over again.
This particular State model has only a lower heating element & thermostat, and is installed in a location that allows me near-to free access all around it, so I know I’m not missing an upper element. So, I’ve checked my wiring connections at the tank, the breaker, and the loads (thermostat and heating element) and all appeared fine; 240VAC where I expected to see it (under normal circumstances).
But, to hedge my bets after a few days, I went ahead and ordered a replacement element from State and picked up a new high limit/t-stat as well, and installed both components. Tank heated up again, no problem… until the next morning, when I found the breaker tripped, again.
Played the reset game with it for a few days (while handcuffed by work), until today, when the breaker tripped, and would not reset even after going to the high limit reset. Instead, I went to try to reset the breaker and got that charmingly loud *POP* and little wisps of smoke from the breaker panel. Left it off, went out to the home improvement store and picked up a replacement 30A DPDT breaker. Installed that, reset the breaker, and *POP*. As it stands, the only thing I’ve not actually replaced at this point is the wiring, and that appears OK.
So. I’m leaving it alone and resigning myself to a cold shower in a few hours before calling an electrician. What I’d like to know is, have any of you run into this before, and what did you determine to be the problem? I’m at the end of three weeks’ troubleshooting on this thing, and I feel like hell that it’s finally defeated me. It looks like a short-to-ground, but I’m at a loss to find where, since up to now, the problem hasn’t been demonstrated consistently.October 8, 2008 at 5:55 pm #9578energyexpertParticipant
To go over the problem:
Did the high limit trip any more after you replaced the thermostat and element?
It sounds like you had an intermittent short associated with a hot tank. Maybe when the tank got hot it would expand enough to touch a bare place in a wire. When the tank was cold it was not touching the bare wire.
It now sounds like you have a good short to ground. In saying good I means it is not now intermittent so you shoud be able to find the problem. Ghosts are hard to find. A volt-ohm meter (less than $20) is a good investment.
Otherwise to check the wiring from breaker to WH open junction at WH and open the wire joints. With everything in the clear turn the breaker back on. If it doesn’t trip the problem is with the WH wiring. If it does trip you have a wiring problem between the breaker and WH.
The high limit will trip if either the thermostat does not open or you have a crack in the element sheath which allow current to go to ground through water so the WH continues to heat after the thermostat interrupts one leg.
DavidOctober 8, 2008 at 9:57 pm #9580OspreyParticipant
After a long day of trying to isolate the short, I finally decided, with the concurrence of the electrician, to bag it and replace the tank. An 11yo HWT is getting there anyway, and with probably close to two inches of sediment at the bottom of the tank, I’d say it was overdue.
We disconnected the tank from the circuit, and reset the breaker – breaker stayed on, so I definitely know the problem was the tank. So far, new tank has heated well and no trouble indications from the breaker.
I was loathe to admit defeat on this one, but after trying everything I knew, and after reviewing the options with the electrician and a good friend of mine, replacing the tank really was the best option.
Thanks for this place, guys – it is a gold mine, and I have referred it to a friend of mine in the HVAC/Plumbing industry as a trove of useful data.
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