osaengineers
Member
Can I feed a 800A, 100% rated breaker with 2 sets of 500KCM rated at 380A each (75 degrees). This would give me a total of 760A. I believe I can.
Thanks for your input.
Thanks for your input.
100% Breakers - Size of conductors
- Thread starter osaengineers
- Start date
- Status
- Location
- Lockport, IL
- Occupation
- Semi-Retired Electrical Engineer
What is the calculated load? If the calculated load is between 761 and 800, or if you did not do a calculation, then the ampacity of the cable must be at least as high as the setting of the breaker.
The sequence of steps is
(1) Calculate the load.
(2) Select a cable that has enough ampacity for that load.
(3) Select a breaker that can protect the cable.
The sequence of steps is
(1) Calculate the load.
(2) Select a cable that has enough ampacity for that load.
(3) Select a breaker that can protect the cable.
eric stromberg
Senior Member
- Location
- Texas
It also depends on the source. If you are feeding this breaker from a 4000 amp bus, and the distance is between 10 and 25 feet, the cable will have to be sized at 1/3 the feeder OCP. If the feeder is protected by a 4000 Amp breaker, the cables would have to be rated for 1333 Amps. (Check out the Feeder tap rules: 240.21(B))
What is protecting this cable on the upstream side?
Eric Stromberg, P.E.
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