AnsweredAssumed Answered

Does my industrial enclosure require a door interlock to prevent the non-diconnect door from closing?

Question asked by jwflaherty on Mar 10, 2020
Latest reply on Mar 10, 2020 by jwflaherty

We have a machine with a 2-door enclosure (Saginaw Control Engineering SCE-306012WFLP) with a through-door rotary disconnect (Allen Bradley 194R- 194R-J30-1753, 194R-N2,  194R-PYT).

The right side door has the through-door disconnect and the door overlaps the left side door such that the left side door cannot be opened unless the right side door is open.  The right side door cannot be opened unless the through-door disconnect is in the OFF position.

 

Our customer is interpreting  NFPA79 section 6.2.3.1.2 (3) as requiring that the right side door cannot be closed unless the left side door is closed.

 

However, NFPA79 6.2.3.1.2 states: The interlocking means shall meet the following

requirements:

 

  • Utilize a device or tool as specified by the manufacturer of the interlock to allow qualified persons to defeat the interlock
  • Be reactivated automatically when the door(s) is closed
  • Prevent closing of the disconnecting means while the door of the enclosure containing the disconnect is open, unless an interlock is operated by deliberate action

 

We interpret this section only to require that the disconnect cannot be placed in to the ON position unless the door of the enclosure containing the disconnect is closed.  Given the lack of enclosure vendor supplied solutions, we believe that the customer’s interpretation is not correct.

 

So the question is do we need an interlock to prevent the right side door (non-disconnect side) from closing unless the left side door (disconnect side) is closed?

Outcomes