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Water heater calculationsSo when I count calculati #220021
04/11/19 07:23 PM
04/11/19 07:23 PM
watersparkfalls  Offline OP
Member
Joined: Mar 2005
Posts: 233
Washington...Not DC
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

2017 / 2014 NEC & Related Books and Study Guides
Re: Water heater calculationsSo when I count calculati [Re: watersparkfalls] #220022
04/11/19 07:30 PM
04/11/19 07:30 PM
G
ghost307  Offline
Member
Joined: May 2005
Posts: 980
Chicago Illinois USA
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 07:32 PM
04/11/19 07:32 PM
watersparkfalls  Offline OP
Member
Joined: Mar 2005
Posts: 233
Washington...Not DC
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 07:46 PM
04/11/19 07:46 PM
G
ghost307  Offline
Member
Joined: May 2005
Posts: 980
Chicago Illinois USA
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 12:42 PM
04/13/19 12:42 PM
watersparkfalls  Offline OP
Member
Joined: Mar 2005
Posts: 233
Washington...Not DC
Thanks, ghost.
H20

Re: Water heater calculationsSo when I count calculati [Re: ghost307] #220028
04/13/19 12:43 PM
04/13/19 12:43 PM
watersparkfalls  Offline OP
Member
Joined: Mar 2005
Posts: 233
Washington...Not DC
Yeah exactly gym inside google bldg.
H20


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