Unused openings

[chipster]

Metallic boxes used for junction boxes and device boxes have knockouts provided for conductor entry. Do the holes in the side of the boxes used for mounting (approx. 1/8") need to be sealed if surface mounting box to wall?

 

[cripple]

Take a look at 110.12(A)

"(A) Unused Openings. Unused openings, other than those intended for the operation of equipment, those intended for mounting purposes, or those permitted as part of the design for listed equipment, shall be closed to afford protection substantially equivalent to the wall of the equipment. Where metallic plugs or plates are used with nonmetallic enclosures, they shall be recessed at least 6 mm (1/4 in.) from the outer surface of the enclosure."