main wire sizing

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jport

Member
Location
Akron,Ohio
I am bidding a job where i am trying to calculate the main feeder wire size.Ther are a total of 5 meters.The supply voltage is 120/240 single phase. I have (2) 200 amp commercial bypass sockets (200 is mininum commercial amperage) One of the 200 amp panels is basically an office with not much load at all,other than maybe 10 outlets probably on about 4 20 amp circuits and 2 lighting circuits.The other 2oo will have more load on it with a 5HP air compressor.50 amp welder outlet and about 15 20 amp receptacles on about 5 circuits and a couple lighting circuits.The other 3 meters will be 100 amp for 2 small apartments and a 100 amp meter for a house panel that probably won't be used but i am putting it in for code purposes.So there is 700 amps of potential but the whole system MAY pull 200 amps total max.Any help would be great Thanks
 

Dennis Alwon

Moderator
Staff member
Location
Chapel Hill, NC
Occupation
Retired Electrical Contractor
There is not enough info to calculate the service. If you are unsure and you mains are 700 amps then base the conductors on 700 amps.
 

Little Bill

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Staff member
Location
Tennessee NEC:2017
Occupation
Semi-Retired Electrician
I am bidding a job where i am trying to calculate the main feeder wire size.Ther are a total of 5 meters.The supply voltage is 120/240 single phase. I have (2) 200 amp commercial bypass sockets (200 is mininum commercial amperage) One of the 200 amp panels is basically an office with not much load at all,other than maybe 10 outlets probably on about 4 20 amp circuits and 2 lighting circuits.The other 2oo will have more load on it with a 5HP air compressor.50 amp welder outlet and about 15 20 amp receptacles on about 5 circuits and a couple lighting circuits.The other 3 meters will be 100 amp for 2 small apartments and a 100 amp meter for a house panel that probably won't be used but i am putting it in for code purposes.So there is 700 amps of potential but the whole system MAY pull 200 amps total max.Any help would be great Thanks

I don't think you have provided enough information, ie:sq. footage, continuous loads, name plate info etc. If you can do a load calculation on what is there already and the code minimums, someone will be better able to help.
Welcome to the forum.:thumbsup:
 

augie47

Moderator
Staff member
Location
Tennessee
Occupation
State Electrical Inspector (Retired)
Most inspection agencies that I know of look at it as (a) you provide load calculations based on engineering data and/or Art 220, or (b) you size the service based on the sum of the overcurrent protection.
 

jport

Member
Location
Akron,Ohio
I am bidding a job where i am trying to calculate the main feeder wire size.Ther are a total of 5 meters.The supply voltage is 120/240 single phase. I have (2) 200 amp commercial bypass sockets (200 is mininum commercial amperage) One of the 200 amp panels is basically an office with not much load at all,other than maybe 10 outlets probably on about 4 20 amp circuits and 2 lighting circuits.The other 2oo will have more load on it with a 5HP air compressor.50 amp welder outlet and about 15 20 amp receptacles on about 5 circuits and a couple lighting circuits.The other 3 meters will be 100 amp for 2 small apartments and a 100 amp meter for a house panel that probably won't be used but i am putting it in for code purposes.So there is 700 amps of potential but the whole system MAY pull 200 amps total max.Any help would be great Thanks
Right now there is 100 amp 120/240 volt single phase feeding the whole building probably 70 years old and looks a little shakey.The building is 4800 sq.ft.I may have to parrallel some 500 mcm or 350 which in my opinion will be serious overkill.Thanks!!!
 
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