Contractor is asking if a separate disconnect is required for dental x-ray machine if it has an on-off switch. NEC 517.72(A) calls for a disconnect "in the supply circuit," and 517.72(B) requires it to be "operable from a location readily accessible from the x-ray control." Is a local switch considered to be in the supply circuit? And, if so, if the control is across the room, or just outside the treatment room door, would a switch on the machine satisfy the requirement of 517.72(B)? My interpretation would be "no" and "no," but I welcome your thoughts.
My interpretation is that the ON/OFF switch on the X-ray equipment does not meet the requirement in 517.72(A). The requirement is for the disconnecting means to be provided within the supply circuit, which could be a feeder or an individual branch circuit. The definitions for each are clear and unambiguous.
The contractor has to provide a readily accessible disconnecting means for the X-ray equipment.