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#94204 - 07/17/05 08:31 AM h20 heaters
watersparkfalls Offline
Member
Registered: 03/08/05
Posts: 212
Loc: Washington...Not DC
a friend asked me if a 125 amp sub panel would be ok for three water heaters that are 40 amps each.
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#94205 - 07/17/05 08:51 AM Re: h20 heaters
Larry Fine Offline
Member
Registered: 02/18/05
Posts: 693
Loc: Richmond, VA
Is the 40 amps the actual heater current, or the individual circuit ratings?
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Larry Fine
Fine Electric Co.
fineelectricco.com
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#94206 - 07/17/05 08:56 AM Re: h20 heaters
watersparkfalls Offline
Member
Registered: 03/08/05
Posts: 212
Loc: Washington...Not DC
individual circuit ratings
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#94207 - 07/17/05 09:30 AM Re: h20 heaters
renosteinke Offline
Cat Servant
Member
Registered: 01/22/05
Posts: 5316
Loc: Blue Collar Country
Really comes down to the application.

If you're talking about water heaters used as household ones are....heating separate systems, and used occasionally for brief periods, the 125 amp panel should be fine.

If these are used together, as in supplying hot water to a production process, and use continuously, than you have to treat the loads as continuous, and have that 25% "buffer' added in to both your panel and the wire supplying it.
(Use the KW ratings of the heaters for your calcs).
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#94208 - 07/17/05 03:24 PM Re: h20 heaters
Larry Fine Offline
Member
Registered: 02/18/05
Posts: 693
Loc: Richmond, VA
At max proper circuit loading, which would be (40a. x 80%) 32a. each, that's 96 a. total.

Another way, 3 x 40a. = 120a. Either way, you're okay.
_________________________
Larry Fine
Fine Electric Co.
fineelectricco.com
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