220-12 (b) Track Lighting. For track lighting in other than dwelling units or guest rooms of hotels or motels, an additional load of 150 volt-amperes shall be included for every 2 ft (610 mm) of lighting track or fraction thereof.
The requirements of Section 220-12(b) previously appeared in Section 410-102 but they were moved to Article 220 for the 1999 Code since they deal primarily with load calculations.
Suppose a lighting plan shows 62.5 linear ft of single-circuit track lighting for a small department store featuring clothing. Since the actual track lighting fixtures are owner supplied, neither the quantity of track lighting fixtures or the lamp size are specified. What is the minimum calculated load associated with the track lighting that must be added to the service or feeder supplying this store?
According to Section 220-12(b), the minimum calculated load to be added to the service or feeder supplying this track light installation is calculated as follows:
62.5 ft ¸ 2 ft = 31.25 ft
31.25 must be rounded up to 32
32 ´ 150 VA = 4800 VA
4800 VA is the minimum load that must be added to the service or feeder calculation.
It is important to note that the branch circuits supplying this installation are covered in Section 410-101(b). For the track lighting branch-circuit load, the maximum load on the track cannot exceed the rating of the branch circuit supplying the track. Also, the track must be supplied by a branch circuit that has a rating not exceeding the rating of the track. The track length does not enter into the branch-circuit calculation.
Section 220-12(b) is not intended to limit the number of feet of track on a single branch circuit nor is it intended to limit the number of fixtures on an individual track. Rather, this section is intended to be used solely for load calculations of feeders and services.
Joe Tedesco, NEC Consultant