Code Quiz

Apr 23, 2009 11:52 AM, By Steven Owen

When installing electrical equipment in manholes, which are intended for personnel entry, with all of the electrical equipment installed on one wall (opposite electrical cabling), what is the requirement for work space (with respect to the electrical equipment) according to Part V of Art. 110?
Note: The electrical equipment is operating at 240V and has live parts that may require examination while energized.

There is no requirement. Just use good judgment.
With respect to the electrical equipment and its clear work space, there must be a minimum depth of 30 in. as you approach the equipment, 36 in. width, and 72 in. vertical height/headroom.
With respect to the electrical equipment and its clear work space, there must be a minimum depth of 36 in. as you approach the equipment, 30 in. width, and 72 inches vertical height/headroom.
As long as the "qualified person" entering the manhole is wearing Level 4 flame-resistant PPE, including Level 4 flash suit hood, along with 00 rubber insulating liners and leather protectors, hearing protection inserts, safety glasses, and leather work shoes, the issue of clear work space goes away, as the "qualified person" is completely protected.

Answer: C

It is the intention of 110.73 to provide a clear work space for personnel to install, inspect, or maintain electrical equipment in manholes. However, this section of the Code only addresses the clear work space required for the electrical equipment, not the cabling. For systems operating at 600V or less, there is a reference to 110.26.

Owen is the owner and president of National Code Seminars and the holder of master electrician certifications in 46 states. He can be reached at necexpert@aol.com.