502.150 Signaling, Alarm, Remote-Control, and Communications Systems; And Meters, Instruments, and Relays
Informational Note: See Article 805 for rules governing the installation of communications circuits.
Exception: Where current-breaking contacts are immersed in oil or where the interruption of current occurs within a chamber sealed against the entrance of dust, enclosures shall be permitted to be of the general-purpose type.
- Attachment plug and receptacle are listed for use in Class II, Division 2 locations, and listed for use with flexible cords.
Exception No. 1: A Class II, Division 2 listing is not required if the circuit involves only nonincendive field wiring.
Exception No. 2: In industrial establishments where the conditions of maintenance and supervision ensure that only qualified individuals service the installation, the Class II, Division 2 listing is not required when the requirements of list items 502.150(B)(5)(2), (B)(5)(3), and (B)(5)(4) are satisfied and the receptacle carries a label warning against plugging or unplugging when energized.
- The flexible cord does not exceed 900 mm (3 ft), is of a type listed for extra-hard usage, or if listed for hard usage is protected by location.
- Only necessary receptacles are provided.
- Unless the attachment plug and receptacle are interlocked mechanically or electrically, or otherwise designed so that they cannot be separated when the contacts are energized, and the contacts cannot be energized when the plug and socket outlet are separated, a switch complying with 502.115(B) shall be provided so that the attachment plug or receptacle is not depended on to interrupt current.
Exception: The switch shall not be required if the circuit is nonincendive field wiring.