Commercial Service Load Calculations Flashcards
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What is the calculated general lighting load, after demand factors, for a 60,000 sq. ft. commercial office building?
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)).
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?
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)).
What is the minimum calculated load required for 75 linear feet of show-window lighting in a retail store?
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.
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?
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.
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?
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.
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?
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.