Question

1) You have a wall mounted range with a rating of 15kw. Using NEC table 250.55 and demand factor calculations, what is the minimum branch circuit overcurrent protection rating?

2) You have a counter top range rated at 5.5kw at 240 volts and a wall mounted range rated at 7kw that will be placed on the same branch circuit that goes to a single kitchen. Using NEC table 250.55 and demand factor calculations, what is the minimum branch circuit overcurrent protection rating?

Answer 1

Answer:

Table 220.55 should be used but in question it is given as 250.55

1Answer.

Range Demand Load=[Value in column c of NEC Table 220.55]*0.05(Range KW-12KW)+[Value in column c of NEC Table 220.55]

=8*0.05(15-12)+8=9.2KVA

Branch circuit current=(9.2*1000)/240=38.33Amps

so minimum Branch circuit current for protection is 40Amps

2.Answer

Counter top range =5.5KW

Wall Mounted Range =7KW

together total load =5.5+7=12.5KW

so the load can be rounded off to 12KW

Demand load =Value in column c of NEC Table 220.55=8

Branch circuit current=8*1000/240=33.33Amps

so Minimum Branch circuit for Protection is 35 Amps but 40 Amp rating may be used