Could you be a little more specific in what you need?
There is not a specific article that covers VFD's.
The question is can anbody enter the room or is it considered for qualifyed personal only dew to the drive cabinet.
The drive input is 575volt 1800 amp it is supplyed by inclosed bussbar threw the ceiling there is also 2 other controls panel at 480 volt 200 amps each all panel are totaly inclosed the 2 controls panels are hoffman does this room need to be locked and labeled authorized personal only and code would reflect on this Thank you.
The room houses main motor drive and controls panels for a large rubber mixing process machine the purpose of this room is to keep control and drives cool and clean of dust chemicals the room is air tempature controlled.
There is 1 other wall disconnet for central dust collection system it is 100 amp 480 volt
If all of the equipment is "dead front" there is no requirement to lock it. Being that there are electrical controls I would advise it to be labeled but this would not be an NEC requirement.
Most labeling and locking requirements are OSHA stipulated.
I am going to send you over to Electrifier as he is a Michigan inspector. I do not have access to any MIOSHA documents.
Please be patient he may be a few minutes.