Table 220.55, Column C, applies to ranges not over 12 kW. The application of Note 1 to ranges over 12 kW (and not over 27 kW) and Note 2 to ranges over 8 3/4 kW (and not over 27 kW) is illustrated in the following two examples:
A. Ranges all the same rating (See Table 220.55, Note 1)
Assume 24 ranges each rated 16 kW. From Table 220.55, Column C the maximum demand for 24 ranges of 12 kW rating is 39 kW.
16 kW exeeeds 12 kW by 4
5% x 4 = 20% (5% increase for each kW in excess of 12)
39 kW x 20% = 7.8 kW increase
39 kW + 7.8 kW = 46.8 kW (value to be used in selection of feeders)
B. Ranges of unequal rating (See Table 220.55, Note 2)
Assume:
5 ranges each rated 11 kW
2 ranges each rated 12 kW
20 ranges each rated 13.5 kW
3 ranges each rated 18 kW
5 x 12 |
= 60 kW (Use 12 kW for range rated less than 12) |
2 x 12 |
= 24 kW |
20 x 13.5 |
= 270 kW |
3 x 18 |
= 54 kW |
30 ranges |
408 kW total kW |
408 kW ÷ 30 ranges = 13.6 kW (average to be used for calculation)
From Table 220.55, Column C, the demand for 30 ranges of 12 kW rating is 15 kW + (1 kW x 30 ranges) = 45 kW.
13.6 exceeds 12 by 1.6 (use 2 kW)
5% x 2 = 10% (5% increase for each kW in excess of 12 kW)
45 kW x 10% = 4.5 kW increase
45 kW + 4.5 kW = 49.5 kw: (value to be used in selection of feeders)
Article 90 Introduction
General
Wiring and Protection
Wiring Methods and Materials
Equipment for General Use
Special Occupancies
Special Equipment
Special Conditions
Tables
Annex C. Conduit and Tubing Fill Tables for Conductors and Fixture Wires of the Same Size
Annex D. Examples
Annex E. Types of Construction