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Old 09-13-2009, 11:13 PM   #1
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hot water heater wiring

I have a fairly new hot water heater that suddenly stopped producing hot water. There is no power getting to the upper heating element, and as I was looking it over I noticed that the 2 black wires on top are not connected but they look like they once were. The problem is they spark when ever they are touched together. Could anyone give me any advice on how to fix this problem?


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Old 09-14-2009, 05:20 AM   #2
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Make sure POWER IS OFF Then put wires back on (so you dont get any sparks) and is also safe with power OFF mAKE SURE YOU HAVE THE RIGHT BREAKER OFF. Or post some pics of conections so we can see to make sure.


Last edited by 300zx; 09-14-2009 at 05:28 AM. Reason: need pics
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Old 09-14-2009, 06:48 AM   #3
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xeluth: Yes, the CB must first be set OFF before reconnecting. Remember you are dealing with 240V. Its always wise to use a test device across those wires to verify voltage applied.
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Old 09-14-2009, 07:22 AM   #4
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You should not have touched the two black wires to each other. That caused a short circuit.

If the wire ends look beat up that is probably because they were almost touching the screw connections they were supposed to be connected to and a lot of sparking (arcing) was going on. You would need to snip off the beat up end and strip back the plastic insulation to expose new copper wire to attach to the screws. Should the screw terminals also be beat up so as not to hold the wires on, you would need to replace the heating element. Wires need to be wrapped around the screw, not just pushed up against it.
The good conscientious technician or serviceperson will carry extra oils and lubricants in case the new pump did not come with oil or the oil was accidentally spilled, so the service call can be completed without an extra visit.

Last edited by AllanJ; 09-14-2009 at 07:28 AM.
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Old 09-14-2009, 08:12 AM   #5
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If you have not worked on the heater in the past, how come the wires are not connected.
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Old 09-14-2009, 12:34 PM   #6
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It's possible they were disconnected because the upper element is shorted. It should read about 13 ohms and infinite ohms to ground.
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Old 09-15-2009, 09:57 AM   #7
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Actually hot water heaters are a bit complex in how they operate. I would put this in the category of advanced electrical/troubleshooting work and would advise you to call a repair person.

Also the installation instructions can be confusing. The instructions I have looked at include wiring diagrams for many different models. And they can be wired differently depending on the specific model.

In general (keep in mind there are different models which work differently), there is an upper and lower heating element. And there is an upper and lower thermostat.

When the upper portion of the tank has cold water in it, the upper thermostat does two things. It directs all the electricity to the upper heating element ONLY (disconnects the lower element), and powers on the upper heating element.

When the upper thermostat detects that the water in the upper portion of the tank is at the set level, it does two things. It disconnects the upper heating element. And it redirects the electricity to the lower heating element.

The lower thermostat is more simple. It just turns on/off the lower heating element as it detects the temperature of the water in the lower portion of the tank. (But if the upper element is turned on, there will be no electricity provided to the lower element!)

Water heaters are designed this way intentionally. That is so they will not use a lot of electricity all at one time. Then smaller wiring can be used to power just one element at a time. And the electric company does not get a big surge of electric use at 6:00 am when everyone wakes up and takes a shower.

Being as cold water entering the tank is directed to the lower portion of the tank via a "dip tube", the lower heating element runs most of the time.

Heating elements can fail to where there is a dead short, a short to ground, or an open. And they should be tested for this when servicing a water heater.

Then the wire colors used for wiring a water heater may not be like any other home electrical wiring. Thus you would need the installation instructions (refer to the correct model number in those instructions), be able to understand the wiring diagrams, and know how to use a multimeter.

Then also when servicing a water heater, the technician should check that the wiring and circuit breaker to the water heater are the correct sizes, and that the water heater and electrical system is grounded properly. (A good overall inspection of the system.)

Also that a "T&P" (temperature and pressure) valve is installed. (Water boils at 212 degrees F. and creates steam. This can blow up a water heater and launch it through your roof! The T&P valve will open if the temperature is too hot or the pressure is too much.)

If you don't have the installation manual and wiring diagrams, the water heater manufacturer may have this on their web site.
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Old 09-15-2009, 11:11 AM   #8
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Originally Posted by Yoyizit View Post
It's possible they were disconnected because the upper element is shorted. It should read about 13 ohms and infinite ohms to ground.
I agree. When he re-connects the wires the breaker will not reset. Change the element and THEN connect the loose wires. It's the element. Bet on it. Now, "who" is the question? WHO?


If it worked before you worked on it. You did something wrong.
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electrical wiring , hot water heater

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