I am wondering why is it that no-one address' (inspectors) the use of 4/0 AL in a commercial building for 200amp? There where many times in the past in bigger cities that we were not allowed to use the 4/0 @ 200amps unless we submited a load calculation proving that the service would not pull more than the 180amps that 4/0 AL is good for. Now that I am in a smaller town I see the 4/0 AL used to feed most services as if they where servicing a residence.
200 amp Service in Comercial Establishments
- Thread starter Trav1217
- Start date
- Status
- Location
- Chapel Hill, NC
- Occupation
- Retired Electrical Contractor
That's a good question. Some areas around here will require calculations if it appears the service is questionable. Also most commercial jobs are engineered and presumably calculated by the EE- just a guess...
aftershock
Senior Member
- Location
- Memphis, TN
Something I never understood or rather found in the code book is: For instance. #4 AWG THHN is good for 100 amps in residential, but in commercial # 2 AWG THHN is used for 100 amps.
brantmacga
Señor Member
- Location
- Georgia
- Occupation
- Former Child
aftershock said:
i can't cite you the exact code, but if you look on the page before the ampacities chart (i think) you'll see the dwelling service ampacity ratings. the ratings for dwellings are higher because of continuous load factors.
i've used 4/0 AL once in a commercial 200A service, but provided a load calc to the ahj to allow its use. it was a small garage.
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