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Water heater calculationsSo when I count calculati #220021 04/11/19 06:23 PM
Joined: Mar 2005
Posts: 233
watersparkfalls Offline OP
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My question is I have a 250 gallon Water heater do I calculate at 100% or 125%? This is branch circuit not feeder calculations. Thanks

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Re: Water heater calculationsSo when I count calculati [Re: watersparkfalls] #220022 04/11/19 06:30 PM
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G
ghost307 Offline
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That's a big tank.
Is this for a locker room with showers?


Ghost307
Re: Water heater calculationsSo when I count calculati [Re: watersparkfalls] #220023 04/11/19 06:32 PM
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Posts: 233
watersparkfalls Offline OP
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OK I see article 422.10 says 125% but where is the code reference to the breaker size one size higher? My water heater is listed at 87 A so 90 A is next standard breaker size.

Re: Water heater calculationsSo when I count calculati [Re: watersparkfalls] #220024 04/11/19 06:46 PM
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Posts: 984
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ghost307 Offline
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You need to take 125% of the full load current; so it needs to be treated as a 108.75A load.
Make sure to also upsize the wire accordingly.


Ghost307
Re: Water heater calculationsSo when I count calculati [Re: ghost307] #220027 04/13/19 11:42 AM
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Posts: 233
watersparkfalls Offline OP
Member
Thanks, ghost.
H20

Re: Water heater calculationsSo when I count calculati [Re: ghost307] #220028 04/13/19 11:43 AM
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Posts: 233
watersparkfalls Offline OP
Member
Yeah exactly gym inside google bldg.
H20


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