Master Electrician Exam (NEC)Load CalculationsMedium
A commercial kitchen has three 5 kW, 208V single-phase electric cooking appliances. What is the minimum demand load for these appliances, according to NEC Table 220.56?
- A15 kW
- B10 kW
- C12 kW
- D7.5 kW
Show answer & explanationAnswer & explanation
Correct answer: C. 12 kW
According to NEC Table 220.56, 'Commercial Cooking Equipment - Other Than Dwelling Units,' for three units of 5 kW each (totaling 15 kW connected load), the demand factor is 80%. Therefore, the minimum demand load is 15 kW * 0.80 = 12 kW.
Why the other options are wrong
- A. Incorrect. This is the full connected load without applying any demand factor.
- B. Incorrect. This demand factor would be for 2 units (70%) or 4 units (65%).
- D. Incorrect. This demand factor would be for 1 unit (100%) or an incorrect application.
Commercial Cooking Equipment Demand
The reduced load calculated for multiple electric cooking appliances in commercial kitchens, based on demand factors provided in NEC Table 220.56, reflecting the unlikelihood of all units operating at full power simultaneously.
- Applies to commercial cooking equipment, not dwelling units.
- Table 220.56 provides demand factors based on the number of units and total connected load.
- Demand factors reduce the total connected load for feeder and service sizing.
Memory trick: Commercial Cookers: Count and Check Table 220.56.