Outlet box supports (see Appendix B)

1) Except as permitted by Subrule 6), boxes and fittings shall be firmly secured to studs, joists, or similar fixed structural units other than wooden, metal, or composition lath, in accordance with this Rule.

3) Where boxes having any dimension greater than 100 mm are used, they shall be secured on at least two sides or shall be secured to metal supports or to wooden boards at least 19 mm thick that are rigidly secured to the structural units.

4) Where boxes are mounted on metal studs, additional support shall be provided to prevent movement of the box after the drywall is installed.

5) Mounting nails or screws shall not project into nor pass through the interior of an outlet box unless

a) the nails or screws are located so as not to be more than 6.4 mm from the back or ends of the box; and
b) the nails or screws are located so that they will not interfere with insulated conductors or connectors.

6) This Rule shall not apply to boxes and fittings installed after the studs, joists, or structural units have been concealed.

7) This Rule shall not apply to a switch or a receptacle with an integral enclosure for use with nonmetallic- sheathed cable and having brackets that securely fasten the integral enclosure to walls or ceilings of conventional construction.

8) Where a ceiling outlet box marked for fan support is installed, the outlet box shall be

a) securely attached directly to the building structure; or
b) attached by a bar hanger securely attached directly to the building structure.

9) A pendant ceiling fan and all possible accessories weighing 16 kg or more shall be supported independently of the outlet box.

Source: Rule 12-3010, CSA C22.1:21, Canadian Electrical Code, Part 1 (25th Edition), Safety Standard for Electrical Installations. © 2021 Canadian Standards Association. Please visit store.csagroup.org