Free E2 Commercial Service Load Calculations Questions and Answers 1 — Questions and Answers
Question 1: What is the calculated general lighting load, after demand factors, for a 60,000 sq. ft. commercial office building?
- 210,000 VA
- 111,250 VA (Correct answer)
- 105,000 VA
- 98,750 VA
Correct answer: 111,250 VA
Per NEC Table 220.12, the unit load for an office is 3.5 VA/sq. ft. The total load is 60,000 * 3.5 = 210,000 VA. According to Table 220.42, the first 12,500 VA is taken at 100%, and the remainder (197,500 VA) is taken at 50%, resulting in a total calculated load of 111,250 VA (12,500 + (197,500 * 0.5)).
Question 2: A commercial building has 150 general-purpose duplex receptacles that are not used for general illumination. What is the calculated load for these receptacles after applying demand factors?
- 27,000 VA
- 13,500 VA
- 18,500 VA (Correct answer)
- 10,000 VA
Correct answer: 18,500 VA
According to NEC 220.14(I), each receptacle outlet is calculated at 180 VA. The total load is 150 * 180 VA = 27,000 VA. Per Table 220.44, the first 10 kVA is at 100% and the remainder is at 50%, resulting in a calculated load of 18,500 VA (10,000 + (17,000 * 0.5)).
Question 3: What is the minimum calculated load required for 75 linear feet of show-window lighting in a retail store?
- 11,250 VA
- 7,500 VA
- 18,750 VA
- 15,000 VA (Correct answer)
Correct answer: 15,000 VA
NEC 220.14(G) requires a load calculation of not less than 200 volt-amperes for each linear foot of show window. Therefore, the calculation is 75 ft * 200 VA/ft = 15,000 VA. This load is then included in the general lighting load calculation and subject to its demand factors.
Question 4: According to NEC Table 220.56, what is the demand factor for a commercial kitchen with a total of 5 pieces of permanently connected kitchen equipment?
- 80%
- 70% (Correct answer)
- 65%
- 90%
Correct answer: 70%
NEC Table 220.56 provides demand factors for commercial kitchen equipment. For a quantity of 5 pieces of equipment, the table specifies a demand factor of 70%. This factor is applied to the total nameplate rating of all the equipment.
Question 5: For a 480Y/277-volt, 3-phase, 4-wire service with a calculated load of 500 amperes on the ungrounded conductors, what is the calculated neutral load?
- 500 A
- 350 A
- 410 A (Correct answer)
- 200 A
Correct answer: 410 A
Per NEC 220.61, the first 200 amperes of neutral load is calculated at 100%. The remainder of the load above 200 amperes can be reduced by a demand factor of 70%. The calculation is 200 A + ((500 A - 200 A) * 0.70) = 200 A + 210 A = 410 A.
Question 6: What is the calculated load for a 50-foot-long multioutlet assembly in a commercial workshop where simultaneous use of cord-connected appliances is likely?
- 1,800 VA
- 9,000 VA (Correct answer)
- 5,000 VA
- 10,000 VA
Correct answer: 9,000 VA
NEC 220.14(H)(2) specifies that for multioutlet assemblies where simultaneous use is likely, each 1 foot of the assembly is considered one outlet at 180 VA. Therefore, the load is 50 ft * 180 VA/ft = 9,000 VA. This load is then added to the noncontinuous receptacle load and subject to demand factors in Table 220.44.
Free E2 Commercial Service Load Calculations Questions and Answers 1
What is the calculated general lighting load, after demand factors, for a 60,000 sq. ft. commercial office building?