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Code Quiz

Jul 17, 2008 2:49 PM, By Steven Owen

Q. When installing a hand-hole enclosure flush with the surface of the earth surrounding it, do you know how to properly ground the enclosure, including the cover? The enclosure is metallic. The dimension of the hand-hole enclosure is 24 inches wide by 24 inches long by 12 inches deep. The conductors installed in the hand hole are feeders. The feeders are 2/0 AWG THWN-2 conductors installed in Schedule 80 PVC, which are turned up into the enclosure. The equipment-grounding conductor for the circuit is based on the 175A overcurrent device protecting the feeder conductors. What is the appropriate Code section you should reference for this type of installation? What is the appropriate size equipment grounding conductor and equipment-bonding jumper, which will bond the cover, for this installation?

Grounding is not required for enclosures that are smaller than 36 inches wide by 36 inches long by 18 inches deep. Therefore, there is no Code section to reference.
Section 250.66. Minimum conductor size is 8 AWG.
Sections 314.30(D), 250.96(A), 250.102(C), 250.122 and Table 250.122. Minimum size equipment-grounding conductor and equipment-bonding jumper is 6 AWG.
Section 314.27, 250.92, 250.102(C), 250.122 and Table 250.122. Minimum size equipment grounding conductor and equipment-bonding jumper is 2/0 AWG.

Answer: C

As per 250.102(C), 250.122 and Table 250.122, the equipment-grounding conductor and the equipment-bonding jumper for this circuit should be based on the 175A overcurrent device protecting the feeder conductors. This yields a minimum size equipment-grounding conductor and equipment-bonding jumper of 6 AWG.

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.