Wiring in ducts and plenum chambers

1) No electrical equipment of any type, unless marked for the purpose, shall be installed in ducts used to transport dust, loose stock, or flammable vapours.

2) No electrical equipment, unless marked for the purpose, shall be installed

a) in any duct used for vapour removal or for ventilation of commercial-type cooking equipment; or
b) in any shaft that is required by regulation to contain only such ducts.

3) Where cables are installed in ducts, plenums, or hollow spaces that are used to transport or move air as part of an environmental air system or in a duct or plenum chamber to connect to an integral fan system, the cables shall be in accordance with the requirements of Rules 2-130 and 12-100.

4) Notwithstanding Subrule 3), where a plenum or hollow space is created by a suspended ceiling having lay-in panels or tiles, flexible cord not exceeding 3 m in length and terminated with an attachment plug shall be permitted to supply pole-type multi-outlet assemblies, provided that the flexible cord is listed in Table 11 for hard usage and the supply voltage does not exceed 300 V.


5) Where a furnace cold-air return duct is formed by boxing in between joists, wiring methods specified in this Section for use in the particular location shall be in accordance with Rules 2-130 and 2-132.

Source: Rule 12-010, 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