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Thread: SERVICE LOAD CALCULATIONS

  1. #11
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    Quote Originally Posted by ronmath View Post
    I'm not sure why we are disagreeing then and why you state it should be rejected? x KVA per sqft. equals assumed load. I would state that these types of buildings are often in flux as to square footage of Tenants and sizes of buildings where a xxx KVA per sqft. might be more helpful in the long run, especially when writing tenant leases and tenant criteria.
    Justify it however you want, but plan review is about Code compliance, not design. If I were involved with plan review, I'd reject any calculation that does not take the form of what is prescribed in Article 220.
    I will have achieved my life's goal if I die with a smile on my face.

  2. #12
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    I have done service calculations in this format many times. It has never been rejected, nor (I believe) should it. It is not in conflict with 220. For example, 220 tells us how to account for HVAC loads. On a design/bid/build project, for which a complete mechanical, plumbing, and electrical design is issued for bids, and those same design drawings are used by the successful bidder for obtaining the permits, the calculation has to be complete. That is, all the M & P equipment is described in some table that accounts for the electrical load of each item. The service load calculation is the sum of all those loads, with any applicable demand factors included.

    But for a design/build project, the drawings are often submitted for permit before the mechanical contractor has finalized the equipment list. NEC 220 it doesn't give us guidance for those projects for which the HVAC equipment has not yet been selected. Using a VA/SF estimate that is based on past experience is, IMO, a reasonable approach.
    Charles E. Beck, P.E., Seattle
    Comments based on 2014 NEC unless otherwise noted.

  3. #13
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    Quote Originally Posted by Smart $ View Post
    Justify it however you want, but plan review is about Code compliance, not design. If I were involved with plan review, I'd reject any calculation that does not take the form of what is prescribed in Article 220.
    Now that I get your point of contention and why you would reject the loads, I guess I would agree that the actual service calculation given to the city for review should be in concise compliant totals and not require math to be done to reach those totals. In criteria or information to an electrician however, (which I believe this is) it makes much more sense to state how you arrived at those numbers so it can be broken out on a Tenant by Tenant basis. I've also run into many inspectors that want to know how the numbers were arrived at and calculated so they too can feel comfortable with the assumptions. Once again, not sure we are really disagreeing, was just trying to point out to the OP that while all the numbers are not prescribed by the NEC, that does not make them invalid and non code compliant and if given in the correct form, should be accepted by the AHJ.
    Be careful out there, that's why I'm in here.

  4. #14
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    Quote Originally Posted by charlie b View Post
    ... Using a VA/SF estimate that is based on past experience is, IMO, a reasonable approach.
    Quote Originally Posted by ronmath View Post
    Now that I get your point of contention and why you would reject the loads, I guess I would agree that the actual service calculation given to the city for review should be in concise compliant totals and not require math to be done to reach those totals. ...
    It's all about using the correct format. Has nothing to do with how you arrived at your numbers, though noting assumed loads is being professionally responsible IMO.
    I will have achieved my life's goal if I die with a smile on my face.

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