Electric water heater issue

[Colt45ws]

So my water heater started acting up recently, tripping its 25A breaker. Within a few days it progressed to not only insta-tripping the 25A breaker, but tripping the mains 200A breaker at the same time.
I thought well, its probably a bad element. Its 15 years old, so I figured it was likely due for some. I got two new 4500W elements to match its nameplate rating, and both thermostats along with the internal breaker attached to the upper thermostat.
I had a 30A breaker on hand, and knowing tripping wears out breakers quickly and that it wasnt catching the overload before the 200A breaker could trip, I canned the 25A breaker for the 30A. The wiring is 10 gauge, so this is within spec.
I put all the parts in last weekend and its been running great, until the 30A breaker I put in tripped out last night.
Ive looked at the wiring on the heater 3 times and verified its correct.
From what Ive figured, the upper thermostat controls both elements, as it has a terminal for each. Then both elements connect to the other leg via a terminal on the internal breaker. It looks like when the upper thermostat is 'off' or is satisfied with the temperature, then it supplies power to the lower element all the time, going through the lower thermostat first. If a bunch of hot water is used then it cuts off the lower element to run the upper element.
It would have to switch between them because you couldnt run two 4500W elements on a 30A circuit at the same time...that would be 38A total.

So my best guess is the new upper thermostat is not cutting off the lower element when it runs the upper one. The breaker would probably hold that much of an overload for awhile before finally tripping.
Or nightmare scenario is there is a intermittent fault in the wiring between the heater and panel.
Anything I might be missing?

 

[JimPghPA]

Even if both elements were powered for a brief time (which they should never be) it would not be enough to kick the 200 Amp main breaker. Look for something that would draw more than 200 Amps, like a wire worn through the insulation and shorting to ground.

 

[andyd]

A wild guess, check the condition of the insulation under the Romex clamp and the connections in the junction box. Is this aluminum cable instead of copper?

 

[ACMAXX]

If it is instantly tripping the breaker and it's not the elements then take wiring lose from the tank and see if still shorts out. Corroded Alum wire would cause high resistance/ heat woludn't it?

 

[Delta]

Something odd is going on here. If it was the water heater wiring it would just be tripping the heater breaker. I would say something in the panel is going wrong. Or the slight vibration of the 30A tripping is causing a short somewhere causing the main to go. It's hard to armchair diagnose an electrical panel.

Now if this box is a Federal Pacific or Zinsco panel...uh, that's a whole nother' animal.

 

[ArcticDriver]

Great responses above.

In my experience a 15-year old water heater tank is full of several inches of sediment and cannot heat efficiently as a result.

And even less than 15 on well water.

Have you considered replacement?

 

[pcoxe]

Take some amp readings while the elements are on to verify the thermostat is switching and not powering both elements. Also feel the breakers after it's run a while to see if there is heat buildup. Circuit breakers often have a thermal element to allow trip on a constant light overload. Loose connections on a breaker can cause thermal trips too, at either the screw terminal or weak plug-in clips.

 

[Johnny2Bad]

It's probably the thermostat component, that was my problem after I did what you did (replace heater elements).

They're easy to replace, just swapping wires and a few screws; use your phone to take photos of the current installation, take safety precautions, and I'll bet you will be good to go. Mine has been running trouble-free for 8 years since I did the work.

Replace the sacrificial anode while you are at it ... should be done every two years. The parts are cheap, no good reason not to do it all. My water heater was installed in 1982 and still going strong. Maintenance is the key, especially that long forgotten anode part. Ignore that and your heater will die in 8 years.

 

[ArcticDriver]

Originally Posted By: Johnny2Bad

Replace the sacrificial anode while you are at it ... should be done every two years. The parts are cheap, no good reason not to do it all. My water heater was installed in 1982 and still going strong. Maintenance is the key, especially that long forgotten anode part. Ignore that and your heater will die in 8 years.


1982 ?

You must have great water.

 

[Fitter30]

I'd take a good look at your panel and main terminal's, and feel the breakers when the breaker has a load on it to see how warm it is.

 

[SHOZ]

Originally Posted By: Johnny2Bad
It's probably the thermostat component, that was my problem after I did what you did (replace heater elements).

They're easy to replace, just swapping wires and a few screws; use your phone to take photos of the current installation, take safety precautions, and I'll bet you will be good to go. Mine has been running trouble-free for 8 years since I did the work.

Replace the sacrificial anode while you are at it ... should be done every two years. The parts are cheap, no good reason not to do it all. My water heater was installed in 1982 and still going strong. Maintenance is the key, especially that long forgotten anode part. Ignore that and your heater will die in 8 years.
I have well water and a water softener. I take the anode out as it will cause a rotten egg smell if I leave it in. Never had a water heater fail in the 37 years I've been here. Bought one in 1994 to replace the one that was in the hose in 1979 when I bought it. Still going strong on the five year guarantee tank at 23 years..

 

[Colt45ws]

I flushed out the tank via the drain when I did the elements. Got quite a bit of sediment, but not like, pounds or anything. Ive read of people having so much it clogged the drain and couldnt be removed, that wasnt an issue here for certain.
Its all copper wiring. Right not Im thinking of removing the water heater timer from the circuit to ensure something isnt going on there. We never use it anyway. Lost the tab that fit on the clock to switch it too.

There was a black mark on one of the elements when I removed it, so Im pretty sure there was a short but since it was such a dead short as to trip the 200, my fear is the wiring was damaged and I will have to replace it.

I put my clamp meter on it after my brother took a shower and it was drawing 19amps, which is about what a single 4500w element should be doing. Only the bottom was running at the time. Then later after it shut off 0amps.

Im really hoping I dont have to pull the original wiring out and replace it. Granted, its a short run thankfully because if you're looking at the heater and do a 180, you are looking at the panel, but still runs under the floor.

I should add the 200amp breaker hasnt tripped since I replaced the elements and the original 25amp breaker. Only the 30amp, once.

The panel is a Siemens. House is 2001.

 

[SHOZ]

Sounds like the switch between the two elements was not switch one off.