CSLB C-10 Electrical ContractorEquipment and InstallationMedium
A commercial lighting track installation runs 24 feet along a ceiling in a retail store. Per NEC 220.43(B), track lighting loads are calculated at 150 VA for every 2 feet of track length. If this track is supplied by a single 120-volt branch circuit, what is the minimum calculated current the circuit must be able to supply?
- A15 amperes
- B18 amperes
- C12.5 amperes
- D20 amperes
Show answer & explanationAnswer & explanation
Correct answer: A. 15 amperes
Load = 150 VA/2 ft x 24 ft = 1,800 VA. Current = 1,800 VA / 120V = 15 amperes. This load fits within a standard 20A branch circuit but the minimum calculated current is 15A.
Why the other options are wrong
- B. This value does not match the correct VA-to-current conversion.
- C. This underestimates the total VA calculated from the track length.
- D. 20A is the circuit rating needed to serve the load, not the calculated current itself.
Track Lighting Load Calculation
NEC 220.43(B) requires track lighting loads to be calculated at 150 VA per 2 feet of track length for feeder/branch-circuit load calculations.
- Applies regardless of the number or wattage of fixtures actually installed
- Formula: (150VA/2ft) x track length = total VA
- Convert VA to amperes by dividing by circuit voltage
Memory trick: Every 2 feet of track adds 150 VA, no matter the bulbs.