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multifamily load calculation

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    multifamily load calculation

    Does any one have a copy of mike holt's electrical exam preparation book, because I have a question, and here it is "I am studing Multifamily dwelling unit load calculations- standard method and on page 355 question # 2 states each unit of a 20 unit apartment building is 990 sq ft. What is the general lighting net computed demand load for the building. I understand how the following was computed "general lighting,small appliance &laundry circuits" the total conected load is 7470 * 20= 149,400 I understand this calculation,however the next step in this calculation states "next 117,000 va at 35%= 40,950vx remainder va at 25%=7350 MY question is How was 117,000 arived at & how was 7350 arrived at? thank you

    Re: multifamily load calculation

    Starting with the initial 149,400, and using Table 220.11, you have to count 100% of the first 3,000. That leaves 146,400 to be counted with lower demand factors being applied. Of this amount, the VA from 3001 to 120,000 (a total of 117,000) get counted at 35%. Taking 35% of 117,000 gives you the 40,950. Finally, you have accounted for the first 120,000 of the initial 149,400, and that leaves you with 29,400 to deal with. The remainder is counted at 25%. Taking 25% of 29,400 gives you 7,350. The grand total is therefore:
    3,000 (the first 3000 at 100%)
    40,950 (the next 117,000 at 35%)
    7,350 (the remaining 29,400 at 25%)
    Grand Total: 51,300 VA
    Charles E. Beck, P.E., Seattle
    Comments based on 2017 NEC unless otherwise noted.