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NFPA Working Space Depth?

Question asked by mjacoby on Sep 21, 2017
Latest reply on Sep 25, 2017 by david.austin

Hello,

 

         I'm trying to determine the minimum work space depth for a 480V electrical cabinet.  We're installing a new cabinet next spring but, it's 8" deeper than current and we really don't want to move the 22000 kg machine unless we have no choice.  In Chapter 11 of the 2015 NFPA book 11.5 discuss spaces around control cabinets.  Table 11.5.1.1 shows 3 conditions that determine the needed space.  I'm struggling to determine whether I have a condition 1 or condition 2.  This machine is on the 2nd floor of our building and near an outside wall.  There are steel crossbeams that intersect the concrete step that runs the length of the building.  There is 1/2" OSB that covers the walls between the vertical i-beams and the crossbeams (picture attached).  Condition 2 states "Exposed live parts on one side and a grounded surface on the other side."  "Concrete, brick, or tile walls shall be considered as grounded."  Our Facility Engineer stated that the painted concrete step along the wall should be an insulator and not a conductor.  If that's correct, does that put this at a condition 1 or due to the presence of concrete grounded or not it's a condition 2?

 

Any help in solving this would be greatly appreciated!

Thanks,

Matt

 

 

 

 

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