120 v switch for electric element went bad

[dhatfield6]

Start from the beginning. I may have dry fried the element because I know the tank was dry when camping last week. I hooked up city water as usual, and as usual, removed the outside heater cover and flipped the switch to on. Remembering as soon as I made the mistake I flipped it back off. Long story short we used the boathouse the rest of the weekend! After the tank filled and the air was purged from both hot & cold lines I turned the electric switch back on. When I was informed of no hot water I found the the on/off rocker switch froze in the on position. At that point I switched the inside breaker off for the electric element.

Once home I ordered the switch and element, assuming this would cure the problem. Only to find out that the element did not burn open, (both new & old elements ohm'ed the same at 10.5) but what I found was the the connector melted on the hi-limit thermostat. Same wire from the switch!

Could energizing the element without it being completely submerged have caused this? Or could I have something else going on?

 

[uhduh camping]

I might think it was something else. I don't know this for sure. I would definitely put a meter on it checking voltage at every connection starting with power coming to to switch and go from there. But for the future you could turn heater on using gas. If I use gas, I heat up a tankful turn off gas then turn it on again 15 mins before showering. So that I'm not burning gas just to keep water warm though out the day. It will stay hot for a long time.

 

[dhatfield6]

I checked voltage on the element, it was good.

 

[wmtire]

Could energizing the element without it being completely submerged have caused this? Or could I have something else going on?

Possibly, the ECO/hi-limit burning out (which operates like a fuse) is most likely what saved your element. Some times this is a cascading failure and you may lose both from the same event.

I'd keep that new element though, the old one may still give up the ghost.

 

[dhatfield6]

Thanks



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[dhatfield6]

What concerns me though, is it burnt switch and the insulation on the spade connector of the limit switch. These shouldn't get to temps to cause melting. What could have caused this?


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[Herk7769]

This is a common failure mode of the thermal protection for both the AC and DC thermostat units.

 

[wmtire]

What concerns me though, is it burnt switch and the insulation on the spade connector of the limit switch. These shouldn't get to temps to cause melting. What could have caused this?


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It's really supposed to your third line of protection, and to save the wiring.

Your thermostat is your first line, and cuts the heat source off at average of 130 degrees (different t-stats have different temps though, I think the highest is 140)

The second line is the resettable ECO (Emergency Cut off) hi-limit. If the temps reaches 180 degrees inside the tank, then this trips...which can be due to a failure of the thermostat.

The third line is the fusible link burning thru, which shuts power off to the thermostat. I am not sure of how long or the temps reached to cause this. I have just seen several instance sin the forums where an exposed element caused all the above. I think KyDan experienced this with his too.

 

[dhatfield6]

See the burnt lower connector. The fusible link didn't burn open


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[Rich5117]

I think you were on your way to burning out the element, however a weaker link melted first, the connector may have had some corrosion or was not ever properly crimped. Even though it has worked without problem with the element not having something to transfer its heat to the connector overloaded.

 

[dhatfield6]

Could be Rich. I'm replacing the wire as well


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[Danesville]

Rich has a very good point, if the connection is anyway losse it will cause the connector to fail due to arcing on the spade connector causing excessive heat.

 

[dhatfield6]

Wiring connection failed

After verifying the electric element, 120 vac T-Stat/Hi-Limit switch assembly were good, it appears that only the crimped on connector was the problem, causing the switch to fail!

NOW has anyone ever tried to purchase THHW?? ((Thermoplastic Insulation (usually PVC), High Heat Resistant (105°C rating), suitable for Wet locations)).

I can seem to locate it anywhere.

 

[Danesville]

They should be available at a HVAC supplier or local electrical supplier.

 

[5picker]

What Rich said.
When that element got hot and started to draw huge amps, the weak link in the chain melted. I would hang on to that element too... likely won't last long.

 

[5picker]

After verifying the electric element, 120 vac T-Stat/Hi-Limit switch assembly were good, it appears that only the crimped on connector was the problem, causing the switch to fail!

NOW has anyone ever tried to purchase THHW?? ((Thermoplastic Insulation (usually PVC), High Heat Resistant (105°C rating), suitable for Wet locations)).

I can seem to locate it anywhere.

If you can't find it locally as suggested, McMaster-Carr should have it *HERE*

 

[dhatfield6]

No THHW listed