1st 300a service

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rookie4now

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OK, I'm doing my 1st 300a service and was wondering if there are any "gottchas" I should watch for?

It is overhead service and I'll be using the existing 2" IMC and feeding 250kcmil to a 300a disconnect. From there, I will feed two 4 meter gutters and drop down to the subs.

The 250kcmil is OK as per 310.15(B), but I have in the back of my head that if you are feeding more than one sub you can't use that section. am I remembering correctly? I really wouldn't mind going 350 but then the existing IMC would need to be changed. (Maybe I could downsize the neutral & squeeze them in, I haven't checked)

Anyway, anything I need to know about that's different from a typical 200a installation?

Thanks
 
The reason I asked if they were "dwellings" and were and under the same roof is because 310.15 states....

"For individual dwelling units of one family, two family, and multi-family dwellings, conductors as listed in Table 310.15(B)(6) shall be permitted as 120/240-volt, 3 wire, single phase service-entrance conductors, service lateral conductors, and feeder conductors that serve as the main power feeder.....

I read this to mean the "dwellings must all be within the same individual building.

IMO...If you had a series of individual dwellings....such as seperate apartment buildings, even if they were single apartments, you could not use Table 310.15(B)(6) to size the Main Service Conductors, or the feeders to each apartment.

Since they are all under the same roof, they would qualify as a "indivdual"
dwelling unit, and the conductors can be sized by the Table.

Just my opinion
steve
 
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