industrial enclosure front clearance

[Mark Curtiss]

I have a customer whom uses localized Vfd's mounted in an electrical enclosure with and fusible disconnect. By definition, I understand that there must be 42" clearance in front of these panels. At this time, they cannot comply 100% with that rule. It seems 36" may be the best they can do to such a confined industrial area.

Can any exceptions be made if this area is restricted? or tagged with some warning stickers, etc. Also, if all of the 460V components are dead front, can the distance measurement be made from the front of the component to the "grounded" area in front of the panel?

 

[charlie b]

The notion of the area being restricted is beyond meaningless. It runs absolutely contrary to the intent of the rule. The working clearance is there to protect the maintenance worker who has his or her hands inside that panel. The distance is measured from the front of the enclosure (i.e., the panel) to whatever material (metal, concrete, drywall surface, another component, whatever) is in front of the panel.

 

[paul]

Your best bet would be to contact the AHJ and see what their thoughts are.

 

[tom baker]

I had an 480V MCC that was less than 42" but more than 36" from an 12" pipe elbow. I had a insulating cover made for the pipe elbow by a marine sailmaker. Worked just fine, even had it made in red. The working space rule is 36" from an insulated surface...