Depth of Working Space-110.26(A)(1)

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bnbowen@uiuc.edu

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We have a 277/480 volt switchboard 5 feet from a concrete wall. We are placing a 2 foot deep VFD trap filter against the concrete wall facing the switchboard.

Does this comply with "condition 1 at 151-600 volts" as both pieces of equipment are grounded and their "exposed live parts on both sides of the working space that are effectively guarded by insulating materials."

If condition 2 applies, can I measure from exposed life part to exposed live parts. I know we are splitting hairs but the room is only so big.
 
IMO according to the last sentence in 110.26(A)(1) you need to measure from the front of the enclosure.

110.26(A)(1) Depth of Working Space. The depth of the working space in the direction of live parts shall not be less than that specified in Table 110.26(A)(1) unless the requirements of 110.26(A)(1)(a), (A)(1)(b), or (A)(1)(c) are met. Distances shall be measured from the exposed live parts or from the enclosure or opening if the live parts are enclosed.
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bnbowen@uiuc.edu said:
Does this comply with "condition 1 at 151-600 volts" as both pieces of equipment are grounded and their "exposed live parts on both sides of the working space that are effectively guarded by insulating materials."
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Non does Condition 1 not apply, Condition 2 does not apply either. The "exposed live parts" become exposed, when you open the panel or enclosure door. At that point, there is no insulation material in place, since the panel on each side is enclosed in a metal frame. That puts you into Condition 3, and you would need 4 feet between the two components, as measured from their respective front surfaces.
 
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