Storage Water Heaters

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frank2004

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NEC 2005, 422.13
"Fixed water heaters less than 120 gallons shall be considered a continuous load"
This infers when working out the demand to dwelling feeders that the water heater component must be taken at 125%. Is the 40% derating factor of 220.82 applied to the 125% of the water heater or must the feeder be rated for the full 125% of the water heater?
 
Re: Storage Water Heaters

220.82 is the optional method which takes all appliances at nameplate so contiuous loading is not considered in this application.

However, this change does indicate that continuous loading shall be applied to the standard feeder and service calc.

I believe this change does more to comply with the Style Manual and to clear confusion of what the old 125% requirement meant when applying the load(s) to feeders and services.
 
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