Wiring electric water heater


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Old 03-15-04, 08:14 PM
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Wiring electric water heater

In my search for a new water heater, I have several options. I want to upgrade, but also want to make sure the existing wiring will handle the new heater. Here are the specifics:
Old heater had 2 elements, each 4500W. New one has 2 elements each 5500W. The breaker is 30A. I will assume the wiring is adequate because it was done by an electrician. The wire is labeled 10/3.
With this existing set up, can I install the new water heater or should I go with a similar 4500W water heater? I will probably believe any response, but could I get some details on how you came up with the answer? Thanks for any help,
Josh
 
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Old 03-15-04, 08:27 PM
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99% of all residential electric water heaters installed (on-demand units excepted) have exactly the same circuit requirements: 10/2 with a 30-amp breaker. Not sure why 10/3 was used, but the extraneous wire doesn't hurt (but neither does it help).

So just pick the water heater you want. Then, as a double-check before purchase, make sure the installation instructions call for 10-gauge wire and a 30-amp breaker. It almost certainly will.
 
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Old 03-21-04, 02:00 PM
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Your answer reminded me of something I'd been wanting to check on so I took a look at the water heater installation in the house I recently bought. The label on the unit says 240 VAC only; the upper element is 4500 watts, lower is 4500 watts, total is 4500 watts. The breaker is 20 amps. The wire is circa 1960 and is unlabeled but looks to be 12 AWG or so. Is this acceptable? The unit was replaced in 1996 by a licensed electrician (he left his sticker on it).
 
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Old 03-21-04, 02:07 PM
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A licensed electrician should have replaced the wiring with #10 and a 30 amp breaker which is proper.
 
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Old 03-21-04, 02:24 PM
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That's what I thought. I have no problem doing that myself, except I'd have to tear up a bunch of basement ceiling to run a new wire.

Just how safe is this? The water heater works fine and the breaker has never popped in the 8 months we've lived here. I know codes have changed over the years but this setup must've been legal at some time (maybe even when the unit was replaced - this is West Virginia and they tend to be a bit behind on such things).
 
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Old 03-21-04, 02:43 PM
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This has been code for as long as I have know.
4500 240= 18.75 amps.
A 20 amp circuit can have a continuous load of 16 amps.
A 30 amp circuit can have a continuous load of 24 amps.
 
 

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