E2 Commercial Service Load Calculations 3 — Questions and Answers
Question 1: What is the minimum show window lighting load per linear foot required in commercial load calculations per NEC 220.14(G)?
- 100 VA
- 150 VA
- 180 VA
- 200 VA (Correct answer)
Correct answer: 200 VA
NEC 220.14(G) requires a minimum of 200 VA per linear foot of show window for load calculations.
Question 2: When a commercial building has both electric heating and air conditioning as non-coincident loads, what does NEC 220.60 permit?
- Add both loads at 100%
- Use only the larger load and omit the smaller (Correct answer)
- Apply 75% to both loads
- Apply 50% to the smaller load only
Correct answer: Use only the larger load and omit the smaller
NEC 220.60 allows the smaller of two non-coincident loads to be omitted because both will not operate simultaneously.
Question 3: For commercial service calculations involving motor loads, what percentage of the largest motor's full-load current must be added to the total per NEC 220.50?
- 25% (Correct answer)
- 50%
- 75%
- 100%
Correct answer: 25%
NEC 220.50 requires 25% of the largest motor's full-load current to be added to feeder and service calculations.
Question 4: Per NEC Table 220.56, what demand factor applies to commercial kitchen equipment when there are only 2 cooking units?
- 65%
- 80%
- 90%
- 100% (Correct answer)
Correct answer: 100%
NEC Table 220.56 requires 100% demand factor when a commercial kitchen has only 1 or 2 units of cooking equipment.
Question 5: What minimum load must be calculated for each required commercial sign or outline lighting outlet per NEC 220.14(F)?
- 600 VA
- 900 VA
- 1,200 VA (Correct answer)
- 1,500 VA
Correct answer: 1,200 VA
NEC 220.14(F) mandates a minimum 1,200 VA for each required sign or outline lighting outlet in commercial occupancies.
Question 6: An inspector notices a designer used 1,500 VA per circuit for receptacles in a commercial tenant space. What is the correct NEC method?
- 1,500 VA per circuit is correct for commercial
- 180 VA per individual receptacle outlet on the yoke (Correct answer)
- 20 VA per square foot of the tenant area
- 2,500 VA per 20-ampere circuit
Correct answer: 180 VA per individual receptacle outlet on the yoke
In commercial (non-dwelling) spaces, receptacles are calculated at 180 VA per outlet per NEC 220.14(I), not per circuit.
Question 7: A commercial HVAC system has a 40-ampere, 208V, 3-phase compressor motor. How is this load properly treated in a service calculation?
- Continuous load calculated at 80% of branch circuit rating
- Non-continuous load included at 100% FLC
- Motor load added at 100% FLC with 25% of largest motor added separately (Correct answer)
- Non-coincident load that can be omitted if heat is larger
Correct answer: Motor load added at 100% FLC with 25% of largest motor added separately
HVAC compressor motors are included at 100% FLC in the total, and per NEC 220.50 an additional 25% of the largest motor is added.
E2 Commercial Service Load Calculations 3
What is the minimum show window lighting load per linear foot required in commercial load calculations per NEC 220.14(G)?