Buffalo72
New member
- Location
- Knoxville, TN
I have a question about clearance of a 15kV unti sub according to Table 110.34(A) of the NEC.
I am checking some drawings from another firm, and it looks like the clearance shown around a nominal 15kV unit sub, for condition 1 and condition 2 is using the 2501 thru 9000V range, even though it is fed from a 15kV pad mount switch outside the building with 3 phases and ground (no neutral). Since there is no neutral present in the feeder or sub on the 15 kV side, wouldn't the nominal voltage to ground be 15kV, and not the 8.6 kV (15kV / 1.732) that they used?
I am checking some drawings from another firm, and it looks like the clearance shown around a nominal 15kV unit sub, for condition 1 and condition 2 is using the 2501 thru 9000V range, even though it is fed from a 15kV pad mount switch outside the building with 3 phases and ground (no neutral). Since there is no neutral present in the feeder or sub on the 15 kV side, wouldn't the nominal voltage to ground be 15kV, and not the 8.6 kV (15kV / 1.732) that they used?