I have a client who originally specified (for the sake of simplicity I'll make up the numbers)... 10 Apartment Free-Standing Ranges (Cooktop/Oven combo) Appliances in 10 kitchens rated at 10kW (208v)...all to be on a dedicated (3 phase) service feeder.
220.55 Column C would have me calculate the Max Demand based on 10 units total at 25kW.
No Prob.
Now, the client would like to revise his kitchen design to instead be 10 WALL OVENS rated at say 5kW and 10 COUNTER COOKTOPS rated at 5kW. The same functions as before with the same total nameplate ratings just split to 2 units each kitchen fed by 2 separate breakers but all 10 still on the same feeder riser.
Now, it seems 220.55 says I have to use Column B for TWENTY units, so Demand Factor of 28% (100,000 wats x .28 = 28kW)
Same function, same utilization, same total wattage on the service feeder: one is 25kW or is 28kW.
I know I can use either column for the lowest rating when the units are the same # of units, but am I stuck with 28kW now vs 25kW or can I STILL option to use 25kW?
Alt: If I feed each kitchen's 2 appliances (cooktop and wall oven) with one branch circuit and split, would that kitchen be considered to have "one range" per Note 4, for the purpose of Table 220.55? And thus have the service feeder back to 25kW but now just have the BRANCH circuit be one breaker of 50 amps?
220.55 Column C would have me calculate the Max Demand based on 10 units total at 25kW.
No Prob.
Now, the client would like to revise his kitchen design to instead be 10 WALL OVENS rated at say 5kW and 10 COUNTER COOKTOPS rated at 5kW. The same functions as before with the same total nameplate ratings just split to 2 units each kitchen fed by 2 separate breakers but all 10 still on the same feeder riser.
Now, it seems 220.55 says I have to use Column B for TWENTY units, so Demand Factor of 28% (100,000 wats x .28 = 28kW)
Same function, same utilization, same total wattage on the service feeder: one is 25kW or is 28kW.
I know I can use either column for the lowest rating when the units are the same # of units, but am I stuck with 28kW now vs 25kW or can I STILL option to use 25kW?
Alt: If I feed each kitchen's 2 appliances (cooktop and wall oven) with one branch circuit and split, would that kitchen be considered to have "one range" per Note 4, for the purpose of Table 220.55? And thus have the service feeder back to 25kW but now just have the BRANCH circuit be one breaker of 50 amps?