Hot Water Tank Electrical Problem

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  #1  
Old 01-30-02, 07:09 AM
Dave Finn
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Hot Water Tank Electrical Problem

Walking past the hot water tank two days ago I noticed a 'hot plastic' smell. Investigating, I found the plastic on the wire nuts had melted off!

It has two elements, two thermostats. 5500w, 240v.

I cut back and re-made the burned-out connections (I noticed the wire from the circuit breaker is aluminum but haven't changed it - yet)

I pulled the elements and found the top one slightly bent. I replaced both (only about $9 each).

With it newly loaded with cold water I fired it up.

Curious, I checked and found power at each element! After an hour I turned down the top thermostat, heard it click, but still found power at the top element.

I'm now assuming that they cicruit overheated because both elements were being driven at the same time (?). To get through the night, I disconnected the top element figuring that the circuit was designed to handle one on at a time.

I was using one of those simple, screwdriver-like indicators that glows when touched to a live circuit. Am I right to assume that the leads to the top element should have no power present when that thermostat clicks off?

I have the original owner's manual and I've triple-checked the wiring and it is wired as called for.

Any help would be greatly appreciated.

Dave
 
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  #2  
Old 01-30-02, 08:21 AM
Plumber2000's Avatar
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Alot of bad things can happen when working with the wires on the water heater, if they get wired wrong and you can not get it right, PLEASE, and I stress it, PLEASE seek an electrician for help, last thing you need is a fire, the cost of an electrician is ALOT LESS then the cost to replace your house.
 
  #3  
Old 01-30-02, 08:37 AM
Join Date: Dec 1999
Location: Northeastern NC On The Albemarle Sound
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Cool

Your problem is the aluminum wire from the panel.
Aluminum wire is a major fire-hazard if not properly connected (which doesn't sound as if it is).
Replace it A.S.A.P. with 10/2-with-ground copper wire off of a 30 amp breaker.
Kill the main breaker, but remember that the two legs above the main breaker are still HOT even if the main breaker is off. Test before touching.
Put the black and white copper wires on the 30 amp double-pole breaker, and the bare copper ground wire on the ground bar in the panel.
Both the black and white are HOT with that 10/2, with 120v per wire. (No neutral with 240v). Attach either wire to the black and red wires on the heater, and the bare ground wire to the green ground screw on the heater.
The bottom thermostat comes on first and heats up the water, which rises. The power passes through connections on the upper tstat, I believe, but I'm not a licensed pro electrician.
Before you follow ANY of my advice, although I would do the above for myself, go to the Electrical forum here for confirmation from a licensed pro there.
Good luck!
Mike
 
  #4  
Old 01-30-02, 08:53 AM
Join Date: Dec 1999
Location: Northeastern NC On The Albemarle Sound
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Cool

Ron,
Where do I go to find out how to move something from one forum to another? Do you have to be moderator of that forum before you can move anything from it, or just a moderator in general (such as the real estate forum)?
Mike
 
  #5  
Old 01-30-02, 08:56 AM
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You have to be the Moderator of the forum, it's under admin options on the bottom below the thread.
 
  #6  
Old 01-30-02, 09:01 AM
Join Date: Dec 1999
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Cool

Thanks.
 
  #7  
Old 01-30-02, 05:39 PM
Wgoodrich
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Most likely you created a problem that wasn't there. A water heater wiring system often only shuts off one of the 120 volt lines going to the element. The other wire going to the element is always hot. IF you would take off on wire from the element, you will find one wire dead and one wire always hot with 120 volts. When the thermostat turns the heat on that element the both those wires would be 120 volts to ground and 240 volt between the two wires.

You read a false reading called a feed back from the other side through the element.

You aluminum wire would meet the NEC requirements if it is sized 8 awg aluminum or 10 awg copper. Aluminum connections are never supposed to be in contact with copper in that connection. The proper connection would be an antioxidation inhibitor grease applied to the aluminum conductor and an alloy split bolt with an alloy divider keeping the copper conductor and the aluminum conductor separated under that pressure style connection then use filler tape and then electrical tape to finish the connection.

I am not opposed to the advise that a copper branch circuit would have probably been better serving that water heater.

The main point I wanted to make was the false reading you got with your tester. You should have tested between the two conductors attached to the element, then you would have read 0 volts with a proper voltage tester.

The cheapy testers have often caused a false reading as you have experienced because it reads voltage of any kind even the back feed causing the false reading you came up with.

Hope this helps

Wg
 
  #8  
Old 01-31-02, 07:06 AM
Dave Finn
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Thank you all

Thank you all for your help. I now understand why all leads appear hot, and I'll also run copper to the tank (the wiring as it was when I bought the house had aluminum and copper wire twisted under wire nuts - which subsequently melted). I'll also get a licensed electrician to check it out - who knows that other problems the original installer might have left for me!
 
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