We have a vendor who is supplying an integrated motor control cabinet on a piece of equipment. The motor is a 480V, 250HP motor. Down stream of the main CB, the vendor is tapping the power cables between the CB and the 250HP motor contactors to supply 2 small fan motors, a 3HP and a 7.5HP. All motors have dedicated O/Ls, but the smaller 3HP and 7.5HP motors do not have dedicated CBs and are relying on the fault protection of the main CB. I am not seeing how this is allowed under NEC Section 450.53. Can anyone offer their insight? I would prefer to have each small fan motor to have a dedicated CB, but the vendor is then implying there will delivery delays and cost implications. Both fans are required to be running for the main motor to run.
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