upsize breaker for water heater?


Old 12-04-14, 01:19 PM
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upsize breaker for water heater?

I have an electric water heater that is 240V, 5500W. Its manual recommends a 30A breaker. However, the installed breaker is only 25A. The breaker doesn't trip, but it does get mildly warm (not hot) and there is a faint crackling sound.

The water heater is wired with 10/2, maybe 25 feet of wire. Is there a reason the circuit might have been derated to 25A?

Bottom line, should I change out the breaker or am I OK with the one that is there? If I change it out, do I put in a 25A or 30A breaker?
Old 12-04-14, 02:00 PM
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The breaker should be 30A. Crackling sound or buzzing?

Maybe the former water heater was a smaller unit requiring the 25A?
Old 12-04-14, 02:01 PM
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It is best to follow the manufacturer's instruction. #10 is okay for a 30 amp circuit so go ahead and change to 30 amps. As to why it is 25, maybe that was what was on the truck of who ever did the electrical or maybe it was installed for a 4500 watt WH.
Old 12-04-14, 02:19 PM
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Thanks for the replies. WH was replaced by previous owner, but they said it was an upgrade (40 gal to 50) so I would guess the old WH was lower wattage.

I think "crackling" is more accurate than "buzzing" but not sure. It's pretty faint... though I can hear it with the panel door shut but not if I'm more than 10 feet away or so.
Old 12-04-14, 02:52 PM
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National Electrical Code mandates that residential storage tank water heaters be served by a branch circuit calculated at 125% of the load. For a 5500 watt heater that would be 28.65 amperes. Your currently installed 25 ampere circuit breaker does not meet code and should be replaced with a 30 ampere CB.
Old 12-05-14, 10:42 AM
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The noise may be caused by a loose connection to the bus bars. I would check before the bars are ruined. It could also lead to a fire.

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