Having a brain fart

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nickelec

Senior Member
Location
US
Someone please quickly help me out I understand article 230 States service conductors need to be sized per the load connected

But that being said take this scenario into play 3 family building total of four meters

Customer wants as follows 200-amp for his apartment

100 in each other apartment

so a total of 3 one hundred amp panels and 1 200 amp panel

Coming off the utility do I basically add up the sum of all breakers to size the service entrance conductors basically needing a conductor size to be able to handle a 500 amp load

There is no engineering a load calculations this is strictly based on providing the customer they are asking for



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nickelec

Senior Member
Location
US
Not necessarily in New York City residential we don't really deal with that the wire coming in from the utility is always significantly undersized but once it's inside the building we have to adhere by NEC standards I told him about the conductors time from the utility going into a wire way and then feeding individual meters and piles

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oldsparky52

Senior Member
Location
Wilmington, NC USA
nickelec said:
Not necessarily in New York City residential we don't really deal with that the wire coming in from the utility is always significantly undersized but once it's inside the building we have to adhere by NEC standards I told him about the conductors time from the utility going into a wire way and then feeding individual meters and piles

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Once it's inside the building, you have a service disconnect, right?
 
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nickelec

Senior Member
Location
US
Not necessarily no Con Edison has special requirements in regards to a single disconnect for service they try to stay away from have access to un metered conductors so they only allow a single main disconnect for services with 6 or more meters

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nickelec

Senior Member
Location
US
What IAM referring to specifically is as follows

A set of SECS comes in from the utility in an "end box" Wich basically is just term the utility uses for a box that can be locked.

Then from there the SECS go into a wire way feeding individual meters and panels

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oldsparky52

Senior Member
Location
Wilmington, NC USA
nickelec said:
Not necessarily no Con Edison has special requirements in regards to a single disconnect for service they try to stay away from have access to un metered conductors so they only allow a single main disconnect for services with 6 or more meters

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I am unsure of what exactly you are doing, but I would do a load calculation for each residence and then add those together.
 
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oldsparky52

Senior Member
Location
Wilmington, NC USA
nickelec said:
What IAM referring to specifically is as follows

A set of SECS comes in from the utility in an "end box" Wich basically is just term the utility uses for a box that can be locked.

Then from there the SECS go into a wire way feeding individual meters and panels

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How far is it from the end box to the service disconnects? Who owns those conductors? Do they need to be NEC compliant?
 
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oldsparky52

Senior Member
Location
Wilmington, NC USA
nickelec said:
Very close within a few feet usually utility requires within 10'

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Ah, IDKW but I was thinking you were running them a lot farther. Would it be easier to have separate conductors for each meter base from the meter base to the end box? You either make a bunch of splices in your wireway at the meter bases or they get made up in the end box. I would think it would be easier just to make them up in the end box but IDK.
 
electrofelon

electrofelon

Senior Member
Location
Cherry Valley NY, Seattle, WA
Basically, service conductors that are serving multiple service disconnects, only need to be sized to the load, they dont need to be sized to the sum of all the service OCPD's. Service conductors serving an individual disconnect need to be sized to that OCPD (can use next size up rule if applicable). 230.90(A), and 230.90(A) exception #3.

edit: As far as what to do if there are no load calcs and you dont want to do them, I cant say how the inspectors there will treat it. Here no one ever asks for calcs on things like this, and I dont bother doing it, so I usually just guess based on experience. I kinda joke that the riser for services like this are "whatever you want to use" considering 230.90(A) ex 3. A 4 unit with 4 100's plus house I usually do somewhere around 250-350 amps. Might do two sets of 4/0 or 250 AL (288A and 328A) depending on the loads (Usually these have a single riser so there would be .8 derating).
 
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nickelec

Senior Member
Location
US
That's how we treat it as well basically use whatever you think is sufficient and go the next size up, odds are this whole building would never exceed even 100 amps

For this install i would probably run a set of 4/0s or a set of 250s

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