Q. Excluding exceptions, what is the requirement for cabling work space, which includes a requirement for a clear work space not less than __________ wide where cables are located on both sides? In the case of cables installed on one side only, the minimum clear workspace shall not be less than 750 millimeters (2 feet 6 inches) wide. The vertical headroom shall not be less than __________, unless the opening is within 300 millimeters (1 foot), measured horizontally, of the adjacent interior wall of the enclosure.

A) 3 feet - 6 inches / 6 feet
B) the width of the equipment / 6 feet - 6 inches or the height of the equipment
C) 8 feet or the width of the equipment / 6 feet - 7 inches or the height of the equipment
D) 900 millimeters (3 feet) / 1.8 meters (6 feet)

Answer: D

Explanation: What is now Part V of Art. 110 of the 2005 NEC was relocated from Art. 314 during the 2005 Code cycle. To allow adequate space for qualified persons to examine, adjust, or maintain cabling within a manhole or other electric enclosure intended for personnel entry, the minimum requirements of Section 110.72 apply.

For safety’s sake, do not forget that for manholes — or other types of confined spaces — OSHA has rules for safety, which can be found in 1910.146(d). Also, do not forget to check Table 130.7(C)(9)(a) - Other Equipment 1 kV and Above of NFPA Standard 70E to determine the appropriate level of PPE required when examining cables in manholes or confined spaces.

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.