When/why does the Main Disconnect SW need to be fused for a cabinet with multiple loads?

[emiller233]

When does the Main Disconnect sw need to be fused for a cabinet with multiple motors? I'm looking thru the NEC, but not sure where to look...
there will be an enclosure with 2 motors and a small control power transformer

480VAC, 3-phase supply

• NEC 70 table 430.52 says 175-225% for time delay fuses
  • 300HP, 361FLA, Fuse size = 631A … 812.25A
    • motor will be on a soft starter
  • 40HP, 52FLA, Fuse size = 91A … 117A
    • DOL motor starter
  • 750VA XFMR single phase, 2A fuses on the primary side
    • powers control circuit

I think I can use a 400A main disconnect switch on this enclosure. The customer will be responsible for providing upstream circuit protection for this enclosure. what section of code would this be detailed in..?

 

[tortuga]

Article 409 probably 409.21

 

[Elect117]

Part 3 & 4 of 430.

Multi-motor combination loads overload protection (part 3) and ground fault protection (part 4).

A fused disconnect switch will only be required when it is being used to protect that switchboard.

You will need a disconnect for each motor. Potentially, each one will have a fused disconnect or will have a rated breaker in the switchboard. Depends on how each motor is being individually protected / disconnected.

The disconnecting means can not be less than 430.115