Required clearance behind MV Switchgear

[philly]

I have a project where new 13.8kV Switchgear is being installed to replace the existing switchgear. The new switchgear is being replaced in the same location however it has a deeper footprint so the clearance between the back of the switchgear and the wall will only be 3 feet.

Table 110.34(A) requires 6ft between the back of the gear and the concrete wall which would not allow the switchgear to be installed in this location.

In looking at the working distances in 110.26 and 110.34 these only seem to be required when there are work activities in the back of the gear that are performed while the back is energized.

I'm curious to hear others thoughts/opinions on this working distance requirement specifically related to MV switchgear which in which it is very rare to be working in back of gear while energized. The only thing that really comes to mind is checking for the absence of voltage to establish an electrically safe working condition.

Also is the working distance referenced to the back of the gear or to the actual energized bus which may be another foot or two inside the gear?

 

[drktmplr12]

2011 NEC

110.34 Work Space and Guarding.
(A) Working Space. Except as elsewhere required or permitted
in this Code, equipment likely to require examination,
adjustment, servicing, or maintenance while energized
shall have clear working space in the direction of access to
live parts of the electrical equipment and shall be not less
than specified in Table 110.34(A). Distances shall be measured
from the live parts, if such are exposed, or from the
enclosure front or opening if such are enclosed.

Exception: Working space shall not be required in back of
equipment such as dead-front switchboards or control assemblies
where there are no renewable or adjustable parts
(such as fuses or switches) on the back and where all connections
are accessible from locations other than the back.
Where rear access is required to work on nonelectrical
parts on the back of enclosed equipment, a minimum working
space of 762 mm (30 in.) horizontally shall be provided.

The way I read it: If you are replacing any electrical parts while energized, the table applies and distance is from the enclosure. If you only have to service non-electrical parts while energized, 30 inches from the enclosure.

Edit, some manufacturers require additional space to service equipment, check with the manufacturer of the gear to make sure you provide enough space!