for the sake of argument on amperage. i have a T building that needs a feeder to supply 600a for 3 disconnects. the available power source is a 800a H frame service. the feeder has to run over head. any ideas on how to make that happen. any ideas appreciated.
Just for some clarification, do you mean a Tee "shaped" building, and a "Square D" 800A H frame service ?
Along with the clarifications stated by electure, have you compiled Load Calculations for both the New and Existing Services?
To begin with, I suggest contacting the Local Utility's Service Planner, to discuss this upgrade.
Be sure to have at least a basic Load Calculations Database ready for referencing, too.
If this T.I. Work _DOES NOT_ involve the Service Capacity, then ... ???
sorry guys it was late when posted
I have a temporary building needing 600a to feed 3-200 panels installed on Temp Buildings. the service to supply the Temp Building is 150' away and needs to be run overhead. The existing service is 800a and not being used because of construction. It has 4-200a disconnects on service not being used. at first I wanted to used the 200a disconnects to supply the 3- Temp building but discovered they are grouping all three together to make 1 building. i now violate 225.30. im just looking for better ideas thsn mine.
You've still got a LOT of missing details...
Run the three temps to three disconnects for TEMP power -- only... skid mounted as necessary... this was the norm for Cashe Creek casino a 350,000 square foot slab job. The final Service was at 21 kVolts.
Construction power is typically only a TRIVIAL fraction of the final Service demand.
No-one in my career starts off with a built out Service early in construction.
So, you do have me puzzled.
(200 Amp NEMA3R panels are chicken feed and they may be used/ second hand as temp construction power.)
Followed by a final new Service/ daughter distribution center, with it feed underground at a suitable point in the construction...
Or have a new Poco transformer pad set next to the new Service.
Temp power rules over-ride long term Service requirements. (Oriented towards firemen/ emergency responders needing to kill power with less than six throws from one spot.)
Stay with aluminum conductors as O/H copper is too heavy.
An over and under scheme is also possible. I'm forced to guess: is O/H because of a critical access roadway?
( Try horizontal boring -- on a weekend ) Then run the rest of the pipe: cut & cover.)