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Thread: Conductor size for 225a feeder

  1. #31
    Join Date
    Jun 2004
    Cherry Valley NY, Seattle, WA
    Are Y'all finding your supply houses stocking 300MCM? I dont recall ever using it. Of course you could always order it it, in which case Id do THHN colors.
    Ethan Brush - East West Electric. NY, WA. MA

    "You can't generalize"

  2. #32
    Join Date
    Dec 2006
    Eastern Oregon
    Quote Originally Posted by electrofelon View Post
    Are Y'all finding your supply houses stocking 300MCM? I dont recall ever using it. Of course you could always order it it, in which case Id do THHN colors.
    I doubt it, but like you, we'd just order it.

    It sounds like Larry's job has been dragging on for quite a while, so lead time may not even be an issue.

  3. #33
    Join Date
    Dec 2011
    Ocala, Florida, USA
    Quote Originally Posted by Adamjamma View Post
    In code I have not seen too much except for the call for calculations, but since there is no tenant there are no loads to calculate, if I understand correctly.

    So, if it was me, which it is not, I would size for the maximum the box can handle, which was stated as 225... then leave it for the tenant to finish up from there...
    Because if I run it for 180 or for 195 and the next tenant needs 225... how do they get it?

    Of course, if it is close enough you could just put in two large enough conduits to allow a 400 amp service to be run to it, and then leave the rest until a customer wants to get power...
    I chose yours to comment on, not to argue directly with you, but because it segways in to what I have to say. Technically you could calculate lighting per the required amperage in 220 and however many receptacles are in there added along with any HVAC and use that even if it is only 100 amps or less. It is the on the tenant when they improve the space to ensure that the MOCP is enough to handle the NEW loads. Depending on the location, a restaurant with no gas, or a tanning bed salon could lease the space next week and need 400 or 600 amps.

    So, as far as the OP's original question, there is no valid argument that the smaller conductor wouldn't be code compliant as installed. Now it all comes to what is conscientious. The OP didn't give the size of the space or the area that one could anticipate a likely tenant or if there are engineered plans and specs, what the actual wording is, so I don't think any of us can make a valid call with the information provided.

    I know what I don't know, and I know where to go to find it!

  4. #34
    Join Date
    Dec 2007
    NE Nebraska
    Quote Originally Posted by david luchini View Post
    The Code would prevent whomever comes along to fitout the space from exceeding the 205A ampacity of the feeder.

    Unless there is an actual load of 206-225 amps it is nothing more then design issue to run 250 vs 300 MCM

    Quote Originally Posted by petersonra View Post
    The minimum conductor ampacity is determined by the calculated load. People don't always make a load calculation for this kind of thing, but it is required in a legalistic sense.
    I've got many installs that don't have a load calculation or a very crude one, especially when it comes to a fairly minimal load on say a 200 amp service or feeder.

    Quote Originally Posted by Russs57 View Post
    Geez, you EC's must really get beat up on price/profit. I feel for you.

    If I was the customer, and had any say, it would be at least 4/0, if not 250, copper THHN. You only pay once for doing it right.
    If I was customer and was more concerned about cost - it will be aluminum conductor. If I had other performance concerns it might be copper. If it were supplying sensitive equipment that don't like voltage drop issues, it might even be a larger conductor than what is being suggested here - depending on the details.

    Quote Originally Posted by LarryFine View Post
    I do plan on using the 300mcm al wire. I had another thread earlier this year when the owner wanted to be able to supply 225a using 2" EMT before a redesign lowered the new ceiling height.

    Yes, this project is more than six months old.
    Most owners don't have a clue, if there is a 225 amp feeder breaker they have a 225 amp feed - even if you only ran 10 AWG copper for conductors.

    If owner has his own electrical crew or maintenance crew with reasonable electrical knowledge, maybe you have better chance of them demanding full 225 amps of capacity, especially if that was in a set of plans/in a contract, design build - you weren't necessarily wrong.
    I live for today, I'm just a day behind.

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