Water heater question
Sounds like a bad thermostat, but first...
Your electric water heater should be on a 30 amp breaker with 10/2-with-ground wiring connected to the heater. (If the water heater is more than a certain distance from the panel, there may be a nearby disconnect breaker.)
Turn the heater breaker OFF, and inspect the wiring connections. You may only have a loose wire, or it may be a bad thermostat. Make sure that all connections are tight and you push in the reset trip button on the thermostat.
The black and white wires (both hot from the breaker when the breaker is on) should be connected to the two wires from the heater (twisted and wire-nutted). It doesn't matter which wire is connected to which wire on the heater. Both are 110v hot (there is no neutral with 220v). The bare ground wire goes to the green ground screw on the heater.
Only one element will come on at a time (the lower one first) if the power is on. To check the elements with an ohm meter, with the power OFF, disconnect the wires from the element. No resistance, replace element with same watt and type. If you replace elements, make certain that the water heater is completely full of water before turning the breaker back on or you'll fry the new element(s).
If all connections are tight and the elements are OK, you may have a bad tstat. I never go into the detailed electrical checking process if so. Not worth the trouble. I just replace both tstats. Easy.
Note, sketch or take a digital photo of the tstat wiring layout. Do not disconnect yet. Take the sketch to any hardware, big box or appliance store and get new upper and lower tstats with the exact same layout and number of screws (doesn't have to be same brand).
Replace each tstat wire ONE AT A TIME from the old tstats to the new. Can't go wrong.
Now you should have solved your problem.
Last edited by Mike Swearingen; 11-30-2008 at 04:16 AM.