Looking through the NFPA 79 (2012) for guidance on when and how to use ?Enclosure Interlock and Disconnects?, I?m still a little unclear.
The particular application is an Operator Interface Enclosure (Pendant mount); the enclosure will be fed by a single 120Vac service at 20Amps. Inside the enclosure will be a Convenience Outlet, UPS, Circuit Breakers and terminal strips. Mounted into the enclosure will be a Computer Touch screen (PC/TS, HMI) and either an AC unit or Ventilation Fan & Grille (this hasn?t been decided yet).
I don?t believe I?m required to have Enclosure Interlock or External Disconnecting means (as far as I can tell), if access requires a key or tool and if proper signage is provided as to where the Power comes from.
Is this correct?
The particular application is an Operator Interface Enclosure (Pendant mount); the enclosure will be fed by a single 120Vac service at 20Amps. Inside the enclosure will be a Convenience Outlet, UPS, Circuit Breakers and terminal strips. Mounted into the enclosure will be a Computer Touch screen (PC/TS, HMI) and either an AC unit or Ventilation Fan & Grille (this hasn?t been decided yet).
I don?t believe I?m required to have Enclosure Interlock or External Disconnecting means (as far as I can tell), if access requires a key or tool and if proper signage is provided as to where the Power comes from.
Is this correct?