Fuse sizing for an MCC future expansion

[calabala]

I have another question regarding sizing fuse.

I have an MCC of 180 HP with an incoming feeder of 2 parallel runs 4-350 MCM

Based on Canadian Electrical Code (CEC), Max Amps passing through this cable is 625 A and so is its permissible protective device rating.
To size its fuse, the fuse rating should be 150-175% based on CEC table 29.
I did pick up a fuse of 300 A.

The contrator mentioned that this MCC might expand in the future to add more load on it (that's why they pick up a big cable size)
He is asking if I can pick up a higher rating fuse instead of the 300 A (say for example a 500 A or 600 A) to cope with the future expansion.

As far as I understand, picking up a higher rating fuse will violate the protective device ranges of CEC in table 29.

What do you suggest?

 

[davidbeach]

I don't know the CEC, but assuming that it isn't wildly different from the NEC, and that each motor feeder has its own protection, your fuses in question are to protect the feeders and the bus of the MCC. Your 300A rating is a minimum rating, the maximum rating is the rating of the gear and feeder. Assuming a 600A bus in the MCC there would be no reason not to go with 600A fuses.

 

[calabala]

Thx David Beach for your explanation.
That make sense.