Free E2 Commercial Service Load Calculations Questions and Answers 1

Question 1

What is the calculated general lighting load, after demand factors, for a 60,000 sq. ft. commercial office building?

Accepted Answer

111,250 VA

Answer

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?

Accepted Answer

18,500 VA

Answer

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?

Accepted Answer

15,000 VA

Answer

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?

Accepted Answer

70%

Answer

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?

Accepted Answer

410 A

Answer

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.

(E2) E2 Commercial Electrical Inspector Practice Test

(E2) E2 Commercial Electrical Inspector Practice Test

Free E2 Commercial Service Load Calculations Questions and Answers 1