Two disconnects on one enclosure

[toothless48]

Hello,

My question is whether NEC or other standards prohibit this design choice:

We have an industrial electrical cabinet that receives 480V power from an electrical drop. There is a knife switch disconnect that kills power to the whole cabinet. We would like to be able to disconnect just the 480V branch to our motors and leave the 24V power supplies and PLC active while people work in the hazard area. Is there any guidance in the standards regarding having a lockable rotary disconnect switch on the cabinet in addition to the main knife switch?

Thank you

 

[itsmoked]

I believe you can generally do that but you need to supply clear and obvious signage to the effect that a person working on the system easily understands the setup.

This disconnect removes power from motors only.
To remove ALL power both disconnects must be OFF.

Or whatever similar messaging would get the point across without failure to a person who's never seen the system before.

Keith Cress
kcress -

http://www.flaminsystems.com