Is the 400A breaker able to accept parallel 500s? If so, the UL required bending space would be part of the MCC design and listing process. If the breaker was not able to accept 2x500s per phase and you changed the lugs to make it work, the onus is on you for not telling the MCC supplier that you needed larger conductors, or for swapping the breaker lugs for something it was not approved for.
But no, the bus compartment is not approved as a raceway for conductors, you have no way to properly secure the conductors inside, so during a fault event they will flap around in the bus compartment and damage the insulation, the bus supports, the bus, or all of the above. It’s an Arc Flash event just waiting to happen... That’s not to say it isn’t done, but usually if someone intends on doing that they will order the MCC with “isolated bus”, meaning the bus bars are in barriered areas so that the conductor insulation can’t touch them. I still don’t recommend it though, I’m just saying that I’ve seen it done.
Last edited by Jraef; 07-10-18 at 11:59 AM.
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Many people are shocked when they discover I am not a good electrician...
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