# 2 element electric water heater troubleshooting



## nap (Dec 4, 2007)

either thermostat will read 0 ohm when they are calling for heat. Since the bottom is exposed to cold water due to non-functioning of the lower heating circuit, it will continue to read 0 ohms until the water it is reading is above the set temp on that stat.

so, in other words; that stat may or may not be bad but with the readings so far, there is nothing to say it is bad.

sounds like the wire is broken or burned. Unusual, at least for me. Replace it. 


TURN OFF POWER


disconnect the wire being replaced at both ends. Using a new wire for replacement, make a loop on each the old wire and the new wire interlocking the loops. Make sure the loops are closed well and pinch them so they are as thin as possible as well. Tape over the connection so the end of the wire will not catch on the insulation as you pull it through. Use the old wire to pull the new wire in. You will not hurt the steel tank and if you use a bit of common sense when doing it you should cause little to no damage to the insulation. If it hangs up and starts pulling the insulation, pull it back the other way a bit. Then working it back and forth a bit you should be able to get it to pull through the insulation.


----------



## pnw (Dec 2, 2014)

thank you for the quick response nap!

question about the type of wire to use for replacement:, see added photo here:
http://imgur.com/a/aSKlt#3

Existing wire looks like 14ga solid copper, with label "style 1032 90C 1000V VW-1 LL29012 CSA TEW OR AWB I A/B 105C 600V"

Closest I could find at home depot is 14ga solid copper THHN 105C/600V. Same thermal/voltage rating, but the insulation looks thinner on the new wire. Is this just result of industrial improvement to thinner insulation to achieve same safety standard, or do I need to look for more specific wire type?


----------



## nap (Dec 4, 2007)

different insulation types require different thicknesses. 

I believe the thhn would be acceptable but hang on for a few of the other guys to poke their head in here. 

but it's #14? Seems like my WH wiring is larger than that with a same size element. It calculates out to be OK (18.75 amps- 4500 watts at 240 volts)(don't ask, it was a big discussion not long ago) but for the fun of it I think I would step up a size (plus I always have some #12 laying around so that's what would get used anyway)


----------



## rjniles (Feb 5, 2007)

pnw said:


> thank you for the quick response nap!
> 
> question about the type of wire to use for replacement:, see added photo here:
> http://imgur.com/a/aSKlt#3
> ...


All the residential WHs I have ever worked on used #12. I would use #12 THHN OR THWN. I would love to see the old wire you pull out. Never seen one go bad, ends burnt off,yes. But never an open wire.


----------



## pnw (Dec 2, 2014)

Thank you again nap and rjniles, yes the internal wiring for the thermostats and elements looks same as the 14ga solid copper I bought, just different insulation. The power into the top of the thermostat (terminals 1 and 3 in first photo) is heavier gauge.

I will go with 12ga, and yes, I am very curious what is going on with the "broken" red wire, I have lived in this house for less than a year, so do not have detailed history for this water heater...never heard of a wire failing in this way before...


----------



## pnw (Dec 2, 2014)

The suspect red wire leading to lower element was the issue.

One thing I had concern about was, when pulling the new wire with the suspect wire, if the suspect wire had some physical weakness associated with the poor electrical connection, it would break. It did.

The new photos in the gallery (http://imgur.com/a/aSKlt#0) show the broken wire, and black/discoloration under the insulation. The wire was a little brittle too, not able to sustain much bending before breaking compared to newer copper wire. I confirmed on each broken piece of wire that the resistance was ~infinite; after sanding off the black surface it returned to ~ 0 Ohms. Maybe I could have just sanded the contacts, but given how readily the wire snapped under tensile stress during pull, I'm glad I just replaced it.

I was able to carefully pull the new wire (12ga per suggestions above) using a straightened coat hanger. I'll probably replace the remaining internal wires, as they are all 14ga and I'd like to avoid a repeat of this issue. Is it a reasonable assumption that the failed wire was to due improper gauge, or gauge combined with age (I think the unit was installed in 2003)?

After replacing the wire and powering up, the lower portion of the tank is now hot to the touch.

Thank you again for the helpful discussion!


----------



## nap (Dec 4, 2007)

good to hear. Now it's time for a_ long _hot shower.


----------



## carmusic (Oct 11, 2011)

14ga is ok for 20A easily, remember that those wires are inside the appliance and rules are not the same, the broken wore was probably nicked at installation and it has create a hot spot and wire melted


----------

