Main distribution panel has an 810 amp load with a 1000 amp main breaker. What minimum configuration of the service entrance conductors required to feed the main distribution panel?
With a 1000 amp main breaker, anything that adds up to 1000 amps or better...
The devil is in the details..
is the neutral a current carrying conductor per 310.15(B)(4) {'08}
how many conductors per conduit ?
is ambient a consideration?
Normally (4) runs of 250kcmil cu, (3) runs of 500 kcmil, cu.