Hum...

Easiest and quickest thing to check would be to shut the power off and pull the access panels. Check for any signs of moisture, rust, etc.

If you find any indication of leaking, chances are your heater isn't long for this world.

Thanks for the reply, kframe19. I'll do that. It's a monster, and I'd hate to replace it. But I'd hate it even more to have to replace it in an emergency...

I replaced my 10 year-old 50 gallon electric water heater a few years ago. I had small white pieces clogging up the screens in the shower heads. I had the pieces checked and they were aluminum oxide. Turns out that the aluminum anode was almost entirely eaten up so the tank was not that far off from rusting through. It was a fairly easy job.

Good luck hjihji (however you say that).

It might bad contact points somewhere. Possibly somewhere between a thermostat and the incoming wires there is a bad relay or an arcing wire. It's a job for an electrician.

Suspect you have a pile of sediment built up in the bottom of the tank all the way up to the lower element.

I would begin checking at the circuit breaker. One of the conductor terminals may be loose and the resulting heat is causing the breaker to trip. Right now, the problem is electrical, not plumbing.

I should have give a bit more explanation.

My comment about checking for water inside the access panels is electrical related.

My old water heater, when I first moved into the house, kept tripping the breaker intermittently. It was because the tank was leaking down across the electrical components.

Strongly recommend replacing the water heater, regardless of diagnosis. At 25 years, it should be falling apart before your eyes. Suggest replacing it with 2 40-gallon heaters, with parallel plumbing connections (not series).

you have the classic symptons of a electric heating element in sediment. The only way that I would NOT replace this 25 YEAR OLD MONSTROSITY water heater is if it happened to be one of the very rare Stainless Steel tank units, if so I would flush the tank and replace the elements and thermostats and live happy. Note: the ole kick the breaker back on deal will work a few more times but the RED light is flashing, the robot (from lost in space) is waving his arms Danger Will Robinson Danger LOL

Sometimes you have to be Hercules to be able to get those old, corroded, heating elements out of the tank.

My elec. water heater was just shy of 30 years before springing a leak. (fortunately it was located in the garage but still made a mess).

Don't screw around with it. Just replace it because it's already living on borrowed time. You beat the odds so be happy.

If an element buried in sediment would cause a breaker to trip, why would resetting the breaker allow the unit to function? Wouldn't it trip the breaker again for the same reason?

Absolutely. So it is probably not buried; the sediment has more likely just gotten up to the element.

Normally, the element is submerged in water. Someone please tell us how surrounding the element in wet sediment will cause the breaker to trip? As many technical details in the explanation as possible, please.

This is Jeff, the poster of the original question. I want to thank everyone for their input. The heater is still working- it hasn't tripped again, but now I'm seeing a suspicous dampness on the floor around the unit. It's time for a new one.

I have many questions about which sort of water heater to get. Someone here mentioned two 40 gallon units. I'd like to hear more about that. Rather than post my new question here, I'm going to start a new thread, called: Water Heater- which one should I buy?

Thanks again. This forum has always been a big help to me.