mayanees
Senior Member
- Location
- Westminster, MD
- Occupation
- Electrical Engineer and Master Electrician
Given a 500 kCM cable with 380 amp capacity.
The OCPD is an adjustable trip 600 amp breaker.
The closest settings are:
(1) 0.625 * 600 = 375 amps, &
(2) 0.7 * 600 = 420 amps
240.4 Protection of Conductors says next higher standard overcurrent device rating (above the ampacity of the conductors)
240.6 describes this adjustable-trip application in (B) and (C).
I think I could make a case that 420 amps is warranted. But it's not clear.
Actually, as I reread 240.4(B) - the next higher standard overcurrent device rating is 400 amps - which I don't have adjustment for with that breaker. So, I can also make the case that 375 amps is my preferred adjustment. (We talked it over in the office, and agree that 400 is the next adjustment level, and since it's not available on my breaker, go to 375)
Any similar experiences or case history out there with this type of a situation?
JM
The OCPD is an adjustable trip 600 amp breaker.
The closest settings are:
(1) 0.625 * 600 = 375 amps, &
(2) 0.7 * 600 = 420 amps
240.4 Protection of Conductors says next higher standard overcurrent device rating (above the ampacity of the conductors)
240.6 describes this adjustable-trip application in (B) and (C).
I think I could make a case that 420 amps is warranted. But it's not clear.
Actually, as I reread 240.4(B) - the next higher standard overcurrent device rating is 400 amps - which I don't have adjustment for with that breaker. So, I can also make the case that 375 amps is my preferred adjustment. (We talked it over in the office, and agree that 400 is the next adjustment level, and since it's not available on my breaker, go to 375)
Any similar experiences or case history out there with this type of a situation?
JM
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