Water heater burned white wire, second time.


Old 10-26-11, 11:54 PM
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Join Date: Oct 2011
Location: US
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Water heater burned red wire, second time.

I purchased this 1950's home a while ago and the previous owners relocated the water heater from a closet on the main floor to the attic. It appears to be wired with 14-2 romex wiring that I would assume is 110?. After living here for about 6 months the water heater stopped working and I looked into it and saw the white wire had burned completely off along with the wirenut that was connecting it. So I rewired it and it lasted about a year before it burned again. At this point I am fine with replacing the hot water heater as long as that would be the cause of this. I was told it would be ok to wire a 240 water heater with 110, that the only downside is it would be pulling 1/4 of the power and take much longer to heat water. We are fine with how long it takes to heat water, I am just worried about it burning the wires.

So I would just like to confirm that 1, I can wire a 240 water heater to 110 and it will work ok without issues other then not heating water as fast. 2, is that the burning of the current wiring isnt due to the fast that its a 240 water heater wired to 110, but most likely the water heater itself?

Last edited by permamonkey; 10-27-11 at 12:46 AM.
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Old 10-27-11, 12:30 AM
Join Date: Mar 2006
Location: Wet side of Washington state.
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Nominal voltages in residences are 120 and 240, NOT 110 and 220. Regardless, #14 wire is too small for all but tiny "point of use" water heaters. Look at the label on the water heater and tell us what are the voltage and wattage ratings.

Also, what size fuses or circuit breaker controls the water heater circuit. Is it a single fuse or circuit breaker or two fuses or a doubled circuit breaker? I suspect that you do indeed have 240 volts supplying the heater but the #14 wire is way too small and needs to be replaced.
Old 10-27-11, 12:44 AM
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I appreciate the quick reply. Here are photos as they can explain much better then I can! One clarification on my end is that it is 12-2 not 14-2. Not sure if that makes much of a difference or not.. I should also clarify it was the red wire as you can see in the pics, not white. I had assumed white as I knew it wasn't the black.. So from my limited understanding the wire should be 10-2 rather then 12-2?


Outside view of breaker...

Inside breaker...

Water heater information...

Last edited by permamonkey; 10-27-11 at 01:08 AM.
Old 10-27-11, 01:15 AM
Join Date: Mar 2006
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Thank you for the pictures.

The water heater has 4500 watt elements and that means a current draw of 18.75 amperes. The National Electrical Code (NEC) stipulates that an electric water heater be considered a "continuous load" and have the branch circuit designed for 125% of the rated load of the heater. That means the circuit must be designed for 23.44 amperes. #12 wires are limited to a maximum of 20 amperes so right there the wire size is too small. They really need to be #10 wires.

I can't see what the circuit breaker rating is (should be marked somewhere on the handle or on the back) but that water heater requires a circuit breaker rated at no less than 25 amperes. A 25 ampere circuit breaker is not common so often a 30 ampere circuit breaker is used in conjunction with #10 wire.

The white wire should be "re-identified" to some color other than white, grey or green by use of a permanent marker or tape. This is to signify that it is a "hot" wire in a 240 volt circuit rather than a "neutral" wire in a 120 volt circuit.

At this point your options are to replace the elements in the water heater with ones of a rating not to exceed 3800 watts, get a new heater with 3800 watt elements or replace the wiring from the circuit breaker to the water heater with #10. The third option may also require new wiring from the obviously "stand alone" circuit breaker back to the source and that may require some major electrical work. If the water heater if fairly new the new elements may be the best answer.
Old 10-27-11, 01:22 AM
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I appreciate the incredibly detailed response, especially given how quickly you responded. I think I will change out the elements as it seems to be the most economical way. Looking at guides on line it seems fairly straight forward. Do you happen to know the socket size for the elements?

Last edited by permamonkey; 10-27-11 at 01:43 AM.
Old 10-27-11, 01:52 AM
Join Date: Mar 2006
Location: Wet side of Washington state.
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Dual elements are the norm. Only one element is energized at any one time. The reason for dual elements is that the upper element is used only when the tank is run almost cold and it heats up the top 25% of the tank quicker than would using the bottom element thereby giving you hot water sooner. Once the upper element's thermostat is satisfied it switches the upper element off and then enables the lower element to heat the rest of the tank under control of the lower thermostat. Using only one element at a time reduces the maximum electric current draw of the heater.

The single biggest difference between a standard and mobile home water heater is that the mobile home heater has had some additional testing for use in the mobile home.

Elements are replaceable but there are a few different mounting designs. You need to remove the covers (top and bottom) of your existing water heater and gently move the fiberglass insulation and electric wires to see the element mount. Some simply screw into a standard pipe thread nozzle welded to the tank, some have bolted flanges and there may some other method. BE SURE TO TURN OFF THE ELECTRICITY TO THE HEATER BEFORE REMOVING THE COVERS AS THERE ARE LETHAL VOLTAGES PRESENT!

Sorry, I don't know the required socket size. I do know that the stamped steel "wrenches" they sell for element removal often don't work but instead just twist into a mess of scrap steel when you try them.
Old 10-27-11, 08:03 AM
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The red wire that is shown coming out of the heater does not need to be #10 as it is not part of the premise wiring.
Old 10-27-11, 09:36 AM
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Is the wiring all copper? That picture of the WH top looks like there might be a bare aluminum ground wire.
Old 10-27-11, 11:59 AM
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I moved into a house with similar water heater wiring. It did not last long. One of the first things I did was replace the wire all the way to the breaker panel with #10 and installed a new breaker.

That way the wiring is large enough for the load. And if that load is exceeded, then the breaker will trip before any "sparks fly" or "overheated wiring" causes a fire.

I sleep better at night...

P.S. If you keep that set-up and similar wiring, be sure you have working smoke detectors inside each bedroom as well as outside the bedrooms.
Old 10-27-11, 06:01 PM
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Originally Posted by ibpooks View Post
Is the wiring all copper? That picture of the WH top looks like there might be a bare aluminum ground wire.
I saw that too. I suspect the OP has 12-2 aluminum romex (rated at 15 amps)with aluminum to copper wire nutted connections that are burning up. I think the OP needs a new circuit and probably some work at the service to accept a modern 30 amp 2 pole breaker.
Old 10-28-11, 12:45 AM
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I saw that as well and sorry to be a bearer of bad new to the OP you have alum conductor that why it was burnted up.

The only way you can slove it is run a new NM cable { 10-2 and remark the white to other colours } and that will useally take care of it.


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