Water heater keeps throwing breaker...

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Old 08-28-10, 03:21 PM
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Question Water heater keeps throwing breaker...

We had a plumber come out last night to replace our water heater that was leaking. Water had gotten into where the electric line hooked up to the water heater and thrown the breaker. The plumber hooked up the new water heater, and now it keeps throwing the breaker. Any ideas what might be causing this???
 
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Old 08-28-10, 03:49 PM
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What size breaker? Was the box dried out? How long does it work before the breaker trips?
 
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Old 08-28-10, 03:52 PM
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It's a 20 amp Westinghouse breaker that has a second attached that says "common trip". The breaker will stay on about 5 minutes before it throws. The breaker box didn't get wet. Just the area around where the romex runs in and hooks to the water heater. But the new water heater was dry.
 
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Old 08-28-10, 03:57 PM
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Most water heaters require a 240 volt 30 amp circuit, not a 20 amp. What size heating elements are in the new water heater?
 
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Old 08-28-10, 04:03 PM
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I'm not sure. It's a Rheem 30 gallon heater.
 
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Old 08-28-10, 05:11 PM
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Look at the label on the front of the water heater and look for wattage, what is it? I'd venture a guess that it's a 4500 watt heater because that's the most popular residential electric water heater, but there are other wattages out there too. If so, the 20 amp circuit is too small, you'll need a 30 amp circuit like pcboss stated. That would be a #10 circuit and a 30 amp 2 pole breaker. If your plumber is qualified to perform electrical work, he should have told you.
 
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Old 08-28-10, 06:40 PM
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I would have your plumber come back and fix it. One of the things I've seen in the pass is the plumbers get in a hurry and don't let the tank fill all the way up before turning on the power and most of the time it shorts at the top heating element. Also as stated through out this thread most water heaters require #10 wire and a 30 amp breaker but if it's only a 30 or 40 gallon if might only require #12 wire on a 20 amp breaker. Again, call the plumber back.

Jim
 
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Old 08-29-10, 12:47 AM
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Check label on side of water heater. It will show Volts and Watts.
A 30 gallon water heater is usually 3500 Watts. Divide Watts by 240 Volts to get Amps.
3500 Watt water heater draws 14.58 Amps
4500 Watt water heater draws 18.75 Amps

Now look at your circuit breaker Amps.
20 Amp breaker x 80% = 16 Amp capacity for 20 Amp breaker
30 Amp breaker x 80% = 24 Amp capacity for 30 Amp breaker

Now look at your wire:
Orange color-coded 10 Ga wire is used with 30 Amp breaker
Yellow color-coded 12 Ga wire is used with 20 Amp breaker

3500 Watt water heater needs a 20 Amp breaker with 12 ga wire
4500 Watt water heater needs a 30 Amp breaker with 10 ga wire

If these things do not match up, then they might cause breaker to trip.

A breaker trips because of heat. Is the breaker warm to touch after 5 minutes? A bad breaker, or a loose wire at breaker can also cause breaker to trip. Check if wire is tight. If breaker has started sparking on busbar, then busbar can be damaged, and this can cause breaker to trip. To test your breaker, move water heater wires to another correctly-sized 240 breaker, and see if problem persists.

If wiring seems correct, and breaker is not getting warm, then the upper thermostat on water heater may be bad, or a wire inside water heater may be bad, or the lower element is shorted to ground and tripping the breaker when it turns on. The plumber is responsible for defective water heater.
 
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Old 08-29-10, 10:00 AM
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I would have your plumber come back and fix it. One of the things I've seen in the pass is the plumbers get in a hurry and don't let the tank fill all the way up before turning on the power and most of the time it shorts at the top heating element.
I've seen this condition many times, usually when a homeowner changes the water heater. The top element will burn out instantly if it is not immersed in water. I have never seen this condition result in a short that instantly trips the breaker. What it will do is keep the top thermostat from ever being satisfied which prevents the top thermostat from switching power to the bottom thermostat and element. The result is, no breaker tripping and no hot water either. In the OP, it was stated the breaker trips after about 5 minutes so this obviously isn't the problem.
 
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Old 08-29-10, 10:06 AM
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Check label on side of water heater. It will show Volts and Watts.
A 30 gallon water heater is usually 3500 Watts.
As I stated earlier, 4500 watt electric water heaters are the most popular. Sears used to sell some 5500 watt units many years ago, but almost all two elemnent residential heaters today are 4500 watt. This is a Rheem 30 gallon model.

From Rheem website for a 6 year warranted electric water heater:
Heaters furnished with standard 240 volt AC, single phase non-simultaneous wiring, and 4500 watt upper and lower heating elements.
http://globalimageserver.com/fetchDo...0-9e430f23fef3
 
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Old 08-29-10, 08:07 PM
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Originally Posted by CasualJoe View Post
I've seen this condition many times, usually when a homeowner changes the water heater. The top element will burn out instantly if it is not immersed in water. I have never seen this condition result in a short that instantly trips the breaker. What it will do is keep the top thermostat from ever being satisfied which prevents the top thermostat from switching power to the bottom thermostat and element. The result is, no breaker tripping and no hot water either. In the OP, it was stated the breaker trips after about 5 minutes so this obviously isn't the problem.
CasualJoe, you are correct but if the element has a pin hole in it from this (hot to ground short). Another thing to check is the connection on the water heater. Incoming wires- wire nuts could be loose causing more draw on the circuit. Again, Call the plumber back if he just put it in and I would beleive he would do that if you ask.

Jim

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Old 08-30-10, 07:32 PM
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CasualJoe, you are correct but if the element has a pin hole in it from this (hot to ground short). Another thing to check is the connection on the water heater. Incoming wires- wire nuts could be loose causing more draw on the circuit. Again, Call the plumber back if he just put it in and I would beleive he would do that if you ask.
A hot to ground short could cause a breaker to trip, but like I said, I have never seen a short develop from a dry fired element and I've seen a lot of them. Regardless, by all means, call the plumber back, he has a problem. Just be aware that he may not know the proper corrective measures to take. You still may need an electrican to get involved.
 
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