Do I need a knife switch disconnect on an air compressor?

[retirede]

Yup, and if it has an integral VFD or starter then I would expect it is has a disconnect already. If that is the case I see no need for a safety switch.

Now if all I got is a pressure switch at the compressor and a starter in a MCC bucket (or hung on the wall) 50' away, then yes I want that safety switch at the unit even if it isn't required by code.

The compressors manufactured by the company I worked for that had conventional motor starters never had a disconnect.
The ones with VFDs normally did.

 

[kwired]

The compressors manufactured by the company I worked for that had conventional motor starters never had a disconnect.
The ones with VFDs normally did.

Last larger VFD driven compressor I connected new, (think it was 75 hp), I believe had an integral disconnect. They still wouldn't warranty it if I didn't provide their semiconductor fuse specifications to the supply lines. My thoughts at the time were why didn't they include them within the unit other than this cuts cost some plus opens the door some to get out of warranty claims.