Dwelling load calculation, water heater


New member
Lancaster PA USA
Ref: page 267 0f 2014 Elec. exam prep

Examples calculate water heater at nameplate rating. NEC 422.13 states water heaters (120Gal. or less) shall be calculated as a continuous load (125%) Should the 4500W nameplate rating in the example be increased by 125%? Why or why not? Thanks!!


Senior Member
WHs are calculated as continuous for branch circuit sizing, but not for feeder/service calculations.

422.13 Storage-Type Water Heaters. A fixed storage type
water heater that has a capacity of 450 L (120 gal) or
less shall be considered a continuous load for the purposes
of sizing branch circuits.