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Discussion Starter · #1 ·
I have an electric water heater that suddenly stopped producing hot water. Checked the fuses and they were good. I checked the reset button on the upper thermostat and it hadn't popped out. Checked for voltage at the top two terminals on the upper t-stat and got 120v on each side when going from a ground. When I checked for voltage across those terminals I got nothing. It is my understanding that I should have 240v there. Then I started to investigate my fuse box. The water heater is fed through two 30a screw type fuses. With the fuse box switch on I get 120v on each side of each fuse when going from a ground. When I test across from one leg to the other I get nothing. Also I discovered if I cut the switch off I lose one of the 120v feeds when testing from ground. I'm baffled, and mama's not happy without hot water. Any help would be appreciated.
 

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Mad Scientist
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Did you check to see if the fuses are blown? Where is this switch you refer to? Is the fuse box your main panel, or a small fuse box between the main panel and the water heater?

If one of the fuses is blown, you will still measure 120v on each side of the heating element because the current is passing through the element from the live side to the dead side.

The part that confuses me is that you seem to be saying that you still have 120v on one side of the heating element when you turn off a switch. Can you clarify how the electrical hookup to this water heater is set up?
 

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Discussion Starter · #3 ·
This is a seperate fuse box that even has its own electric meter on the outside of the house and yes the fuses are good. It has a slide type of switch that acts just like a conventional blade switch. When I measured the voltage coming into this fuse box I get 120v on each leg going from a ground, when I measured across these legs I got nothing. I got the same situation on the top two terminals of my upper thermostat on my water heater. Now, this morning, thankfully, I have hot water again! I checked the voltage across the two legs coming into that fuse box and, presto, I have 240v again. I think that I may have a problem with my electric meter. What do you think?
 

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Do you have one of the older type meter for your water heater, with what I guess you could call a glass dome over it, so that you can see into it, or a newer plastic cover, perhaps with a digital meter? To be perfectly clear, I am not an electrician by trade, nor am I associated with a POCO in any way, but I was told by someone who was, quite a few years ago now, that in some areas anyway, the POCO could switch the newer ones off, remotely, during peak usage, or when they otherwise need more power elsewhere on the grid. We had electric water heat for years, and I never experienced this, so never had the opportunity to check it myself, but maybe they only shut off one leg. Might be worth a call to your POCO.
 

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Mad Scientist
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Yep, sounds like it's time to call the power company. Tell them you think you've lost a leg at your water heater meter, and have them come out and check it. Let us know how it goes.
 

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A "Handy Husband"
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You have an intermitant loss of one leg of the 240 volt line. Could be in the meter, the switch you spoke of, or the fuse holders. The reason you see 120 from ground to each leg is that you measure one side from the fuse and the other side is the measurement back thru the water heater coil.
 

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Discussion Starter · #7 ·
well, the power co. was out today and sure enough there was a problem inside my meter. Everything appears to be working good now. Thanks everyone for the advice. I will definetly be back next time I have any problems!
 
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