electrical? on a water heater

Discussion in 'Plumbing Forum, Professional & DIY Advice, Tips & ' started by steelers fan, Jul 26, 2010.

  1. steelers fan

    steelers fan In the Trades

    Messages:
    49
    Location:
    va
    so i got a call today from an existing customer who tells me one of her rental properties the tenant says she only gets about 5-6 minutes of hot water and then it goes cold.So I'm thinking it sounds like the lower element has crapped out.I get there and check it for continuity and its good so I check the upper and its also good.I then check every contact on its own and I get 120 volts across every one of em.But when I check both hot legs together I get nothing,I check both hots where they com into the heater same,and i check both at each element same,nothing.Yet when I check it at the panel box i get 240.Now I call the owner and the truth comes around a little more,seems he was playing electrician over the weekend trying to install some new flourescent lights in the kitchen when he ran across what he says were two 120 legs tied together and that did not make sense to him so he seperated and capped them,doesnt really make sense to me either but then again I'm not a sparky.I checked every contact on the w.h and got 120 everywhere but when i check both hot legs nada.The heater worked fine till he played weekend warrior now nothing and the breaker tripped out on him.So I told him to call an electrician to check it out.Now admittedly I'm a greenhorn in plumbing so I'm not sure if a bad thermostat will mimic this or not so here I am asking for some input from you guys.I am just baffled that I can get 120 at each hot leg but not 240 across them both .Can anyone enlighten me?
  2. Doherty Plumbing

    Doherty Plumbing Journeyman & Gas Fitter

    Messages:
    810
    Location:
    Penticton, BC
    That is really odd because your HWT SHOULD be on it's own circuit run right from the panel to the tank with no junctions in between.

    Are you sure you had your meter set on the right setting to measure 240v?

    And to be clear you get 120v from each leg when you measure from the hot leg to ground?

    Also it could be coincidental and perhaps the dip tube is broken off inside the tank and the cold water is short cycling.

    But telling him to call a Sparky is the right thing to for sure. Liability wise you shouldn't be screwing around with the wiring in someone elses home if you're not a ticketed electrician.
  3. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    21,834
    Location:
    New England
    If both of the hot leads got tied together, there would have been a big spark, and the breaker should trip. It may be that only one leg of the breaker tripped or the other side is arc'ed together now, and you have the same phase on both wires...it would show 120vac from each of the hots to ground, but since they are now together on the same leg, no potential between them. So, the breaker might be shot. Usually, that run would be a 'home run', i.e., no junction boxes except maybe at the unit itself. There would not normally be a place to muck with it.

    People should not muck with stuff they: 1, don't own, and 2. don't understand.
  4. steelers fan

    steelers fan In the Trades

    Messages:
    49
    Location:
    va
    I thought of the dip tube also but in talking with the tenant and the landlord the w.h. worked fine till he came to install new lights in the kitchen,which is when the circuit breaker tripped for the w.h. and ever since they have zero hot water.I flipped the breaker back on and hit the reset button on the w.h and thats what I got 120 using my multimeter black to ground red to hot.My old analog multi died on me so i was using a little digital radio shck version I've never used before but it seemed to work fine it has an auto ac voltage sensor and like I said I got 240 at the breaker.I'm just stumped as to how I can get 120 at each hot leg on the heater but not get 240 across them.IDUNNO
  5. Doherty Plumbing

    Doherty Plumbing Journeyman & Gas Fitter

    Messages:
    810
    Location:
    Penticton, BC
    I'm not an electrician but really?

    You should beable to tie two power sources togeather that are the same phase without sparks.... this would be a normal junction, no?

    And I would think if you tied two 120v out-of-phase conductors togeather you would trip the panel's main breaker.
  6. steelers fan

    steelers fan In the Trades

    Messages:
    49
    Location:
    va
    jad not sure if it was a junction at all the H.O. told me what he found above the existing old kitchen lights.I asked if it was in a j-box and he said no and told me to open up the new lights and take a look for myself to see if I could fix it.Not being an electrician I politely declined and told him I'd try to research it a little but in the mean time get an qualified electrician to diagnose it.Yea I feel ya doherty I'm not gonna put myself or anyone else at risk messing with stuff I have no bussiness tinkering with.
  7. Doherty Plumbing

    Doherty Plumbing Journeyman & Gas Fitter

    Messages:
    810
    Location:
    Penticton, BC
    Sounds to me like Jad said and they are now both on the same phase. But this would seem impossible to me because if they are on a double breaker then each leg of the breaker touches only one side of the bus bars meaning they should be out-of-phase of each other giving you 240v...

    And again the wiring for the tank shouldn't be split off to other fixtures it should be on its own circuit.

    The next thing I would do is a continuity test on the circuit.... well right after I phoned a sparky :D. But this would be iffy if they have tied in other power sources, or something, into the circuit. But you could always test the circuit for power after you've disconnected it from the panel.
    Last edited: Jul 26, 2010
  8. steelers fan

    steelers fan In the Trades

    Messages:
    49
    Location:
    va
    thanks for the help guys just trying to understand it .I guess I need to break out my basic electricity book and get back to studying,but in the meantime I'm calling a sparky out to take care of it
  9. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    21,834
    Location:
    New England
    What I meant, was if you tied the two hots from the 240ac circuit...POW!
  10. Doherty Plumbing

    Doherty Plumbing Journeyman & Gas Fitter

    Messages:
    810
    Location:
    Penticton, BC
    Yes ok that makes sense and yes you're right about that :D Happened to me once. I didn't do the install but they called saying they had no hot water and it was because the breaker kept tripping cause someone had hooked the two 120 hot lines togeather lol.
  11. Furd

    Furd Engineer

    Messages:
    446
    Location:
    Wet side of Washington State
    I'll bet it is a GE panel. Some GE panels have the ability to move the circuit breakers in a manner that WILL allow you to have what should be a 240 volt (two-pole) breaker mounted to the same leg. If I am correct in my assumption it will take moving at least the water heater circuit breaker and one other circuit breaker to fix.

    I also suspect that what the owner thought was an incorrectly wired circuit was instead a "multi-wire branch circuit" that used a shared neutral. If he incorrectly repositioned the circuit breakers on this type of circuit he could have a serious hazard in that the neutral could be connected to carry TWICE the normal current.
  12. nhmaster3015

    nhmaster3015 Master Plumber

    Messages:
    836
    Location:
    The granite state
    I'm with Furd. GE Bryant and some older ITE panels all would let you pull 120 off the same leg if you were not paying attention to the buss bar.
  13. Lightwave

    Lightwave New Member

    Messages:
    98
    Location:
    Vancouver, BC
    You'll get zero volts across the hots but 120 from hot to ground if both hot wires are attached to the same leg (phase) at the panel. Each hot must be on a different leg to get 240.

    If you're getting 240 between hots at the breaker tank but 0 between hots at the tank, then somebody has done something very stupid with a junction box between the panel and the tank.
  14. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,315
    Location:
    Cave Creek, Arizona
    NOrmally the entire water heater circuit is isolated from the ground or neutral. Therefore, since you are getting a reading of 120 volts, you have two problems.
    1. Something is shorted out, probably the lower element.
    2. One of the two leads to the water heater is broken, possibly in the "J" box on top of the heater.
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