110.31 Enclosure For Electrical Installation

[Puppy6]

Hi guys,

Wanted to get your opinion on your thoughts on this section.

If electrical equipment rated over 1000V is installed indoors with a fence surrounding the equipment, do you think the clearances from table 110.31 need to be met?

Is that table only for outdoor installations?

Also if the equipment can provide power feeders to other equipment from multiple sides, would you provide that minimum clearance on all those sides or only the front of the equipment?

 

[jim dungar]

Totally enclosed equipment does not require any fencing per NEC.

Working space requirements should be met in front and back. Side panels are not normally removable when energized.

 

[Carultch]

110.31 is for equipment with permanently exposed live parts. For equipment normally behind a dead front, 110.26 and 110.34 apply instead. A metal fence counts as a Condition 2 surface. For determining whether a surface needs this space, consider whether it is electrical maintenance (full clearance), or whether it is non-electrical work (e.g. air filters), which only require 30" of workspace depth.

For medium voltage equipment, consider whether a hot stick will be used. As in, an insulated stick for maintenance on live medium voltage equipment. If the user standardizes on a 25kV hot stick, even for 15 kV equipment, there won't be enough space if you designed for the 15 kV clearances. I usually plan on at least 10 ft for hot stick maintenance.