LRB
Member
- Location
- Interior Alaska
Good evening
Hope everyone had a nice Memorial Day week end.
We are pulling a new feeder for one generator. Generator is 3 Ph. 480 V, 150 KW, 225 A.(see one line, we have 2 ea 150 KW gen sets, not set up for parallel service) The existing feeder starts out with 750 MCM AL XHHW and transitions to 350 MCM CU XHHW. Run is approx 400 ft. This is a CO-OP grain elevator and fertilizer complex.
Max current load during fall harvest (approx 6 weeks max):
1 ea 40 HP 52 A * 1.25 = 65
2 ea 30 HP 80 A
2 ea 25 HP 68 A
1 ea 20 HP 27 A
1 ea 15 HP 21
4 ea 7 1/2 HP 44 A
4 ea 5 HP 30 A
Total HP 230 HP
Max load I have observed: approx. 200 amp. Normal load about 180 amp.
Calculating Feeder per NEC 430.24 (2014), conductor A rating: 335 A, = 600 MCM AL, or 400 MCM CU
We are expanding our drying with an additional drier, yet to be purchased. It will probably have 3 fans in the range of:
1 - 50 HP -65 a * 1.25 =81a
1 - 30 HP -40 a
1 - 25 HP -34 a
Total load on new feeder: 155 A =3/0 AL or 1/0 CU
New feeder will be dedicated to new dryer, as will be the gen tied to the new feeder. Other 150 KW gen will supply existing loads, however, 250A backfeed breaker ((with Kirk Interlock) will be included in order to feed entire system from either Gen Set, in case one of the Gen Set is down. Obviously some loads would need to be load shed.
Sizing feeder based on gen capacity at 125 % short term overload, I calculate 225 X 1.25=280 A which would equate to 500 MCM AL or 300 MCM CU.
At this time I am intending to use feeder based on max capability of Gen Set. Please give me your opinion.
LRB
View attachment 17670
Hope everyone had a nice Memorial Day week end.
We are pulling a new feeder for one generator. Generator is 3 Ph. 480 V, 150 KW, 225 A.(see one line, we have 2 ea 150 KW gen sets, not set up for parallel service) The existing feeder starts out with 750 MCM AL XHHW and transitions to 350 MCM CU XHHW. Run is approx 400 ft. This is a CO-OP grain elevator and fertilizer complex.
Max current load during fall harvest (approx 6 weeks max):
1 ea 40 HP 52 A * 1.25 = 65
2 ea 30 HP 80 A
2 ea 25 HP 68 A
1 ea 20 HP 27 A
1 ea 15 HP 21
4 ea 7 1/2 HP 44 A
4 ea 5 HP 30 A
Total HP 230 HP
Max load I have observed: approx. 200 amp. Normal load about 180 amp.
Calculating Feeder per NEC 430.24 (2014), conductor A rating: 335 A, = 600 MCM AL, or 400 MCM CU
We are expanding our drying with an additional drier, yet to be purchased. It will probably have 3 fans in the range of:
1 - 50 HP -65 a * 1.25 =81a
1 - 30 HP -40 a
1 - 25 HP -34 a
Total load on new feeder: 155 A =3/0 AL or 1/0 CU
New feeder will be dedicated to new dryer, as will be the gen tied to the new feeder. Other 150 KW gen will supply existing loads, however, 250A backfeed breaker ((with Kirk Interlock) will be included in order to feed entire system from either Gen Set, in case one of the Gen Set is down. Obviously some loads would need to be load shed.
Sizing feeder based on gen capacity at 125 % short term overload, I calculate 225 X 1.25=280 A which would equate to 500 MCM AL or 300 MCM CU.
At this time I am intending to use feeder based on max capability of Gen Set. Please give me your opinion.
LRB
View attachment 17670