Working Clearance 110.34(A) - 5KV Switchgear

[nhee2]

In an existing installation, a 4160 VAC 2-section Metal Clad Switchgear has 42" working clearance to a grounded wall in the rear. Switchgear contains generator breaker/protective relaying/transformer protection for a distributed generation facility. I originally thought this was a violation of Table 110.34(A) condition 2 which would require 5 ft of clearance, but I am assuming they must have used the exception since the rear sections contain no "adjustable or renewable parts). However, when the exception refers to 'all connections are accessible from locations other than rear' - what connections is this referring to - switch/relay/fuse/component connections? Or field conductor terminations? Because the 4160 field terminations are located in the rear, which would make this install a violation of 110.34. (2014 code).

If the gear is not going to be inspected/maintained while energized, does 110.34 even apply? Likewise, does the requirement in 110.33(A) apply?

The existing gear in question is crammed into a tight space, and customer wants to add a section - I am just trying to determine whether the existing is even allowed.

 

[charlie b]

For starters, a 4160 volt system will have a voltage to ground of 2401 volts. So the Condition 2 clearance requirement is 4 feet, not 5 feet. But you don't have that much room anyway.

I believe that the exception is talking about any and all connections that might require inspection or adjustment, and that would include the 4160 V terminations. So I think you have a violation on your hands. One possible solution is to install some insulating material on the wall, so as to turn that wall into a ungrounded surface. That would put you into Condition 1, and the clearance requirement is only 3 feet.

 

[charlie b]

If the gear is not going to be inspected/maintained while energized, does 110.34 even apply?

This is subject to interpretation. But I suspect that very few, if any, inspection authorities would accept that reasoning.

 

[nhee2]

Thanks Charlie B. Good point on Nominal Voltage to ground which I overlooked.

This is subject to interpretation. But I suspect that very few, if any, inspection authorities would accept that reasoning.

I would have specified 110.34 working clearances around front and back, with area entrances as required by 110.33. The existing install meets neither. But I am generally conservative (sometimes overly conservative) so was looking to see if others would interpret existing installation to meet code.