cdcengineer
Senior Member
Alright, good-morning all.
I am posed with a new one here this morning. I have (28) dwelling units, (14) with 8kw range & (14) with 2.766kW cooktops. The units are served with 120/208V, 1-phase, but the distribution panel which serves this bank of units is 208Y/120V, 3-phase.
220.55 allows where two or more single phase ranges are supplied by a 3-phase feeder, the total load shall be calculated on the basis of twice the number connected between any two phases.
Therefore we have a max of (5) ranges and (5) cooktops connected between any two phases. I was originally under the impression that I should calculate the ranges as:
Twice the maximum - 2 x 5 = 10, table 220.55 --- Column C - 25kW+(25kW/2) = 37,500
And the cooktops should be handled as:
Twice the maximum - 2 x 5 = 10, table 220.55 --- Column A 49% x (10 x 2.766kW) = 13553 + (13553/2) = 20,330
Total Electric Cooking = 37,500 + 20,330 = 57,830
However after reading a bit closer, I'm now considering that table 220.55, note #3 applies. Which after still considering that there are only (5) of each type of cooking appliance connected between any two phases, this would result in the following:
Cooktops - Twice the maximum - 2 x 5 = 10, table 220.55 --- Column A 49% x (10 x 2.766kW) = 13553 + (13553/2) = 20,330
Ranges - Twice the maximum - 2 x 5 = 10, table 220.55 --- Column B 34% x (10 x 8kW) = 27200 + (27200/2) = 40,800
Total Electric Cooking = 20,330 + 40,800 = 61,130
And finally there is always the possibility that this should be handled as if all the appliances are combined:
Twice the maximum - 2 x 10 = 20, table 220.55 --- Columns A & B [35% x (10 x 2.766kW)] + [28% x (10 x 8kW)] = 32081 + (32081/2) = 48,122
I have performed multi-unit calculations before, but never with different size electric cooking appliances. Can anyone provide some opinions on how this should be handled?
As always, your input is greatly appreciated.
I am posed with a new one here this morning. I have (28) dwelling units, (14) with 8kw range & (14) with 2.766kW cooktops. The units are served with 120/208V, 1-phase, but the distribution panel which serves this bank of units is 208Y/120V, 3-phase.
220.55 allows where two or more single phase ranges are supplied by a 3-phase feeder, the total load shall be calculated on the basis of twice the number connected between any two phases.
Therefore we have a max of (5) ranges and (5) cooktops connected between any two phases. I was originally under the impression that I should calculate the ranges as:
Twice the maximum - 2 x 5 = 10, table 220.55 --- Column C - 25kW+(25kW/2) = 37,500
And the cooktops should be handled as:
Twice the maximum - 2 x 5 = 10, table 220.55 --- Column A 49% x (10 x 2.766kW) = 13553 + (13553/2) = 20,330
Total Electric Cooking = 37,500 + 20,330 = 57,830
However after reading a bit closer, I'm now considering that table 220.55, note #3 applies. Which after still considering that there are only (5) of each type of cooking appliance connected between any two phases, this would result in the following:
Cooktops - Twice the maximum - 2 x 5 = 10, table 220.55 --- Column A 49% x (10 x 2.766kW) = 13553 + (13553/2) = 20,330
Ranges - Twice the maximum - 2 x 5 = 10, table 220.55 --- Column B 34% x (10 x 8kW) = 27200 + (27200/2) = 40,800
Total Electric Cooking = 20,330 + 40,800 = 61,130
And finally there is always the possibility that this should be handled as if all the appliances are combined:
Twice the maximum - 2 x 10 = 20, table 220.55 --- Columns A & B [35% x (10 x 2.766kW)] + [28% x (10 x 8kW)] = 32081 + (32081/2) = 48,122
I have performed multi-unit calculations before, but never with different size electric cooking appliances. Can anyone provide some opinions on how this should be handled?
As always, your input is greatly appreciated.