Information Bulletin: Protection of electrical raceways and cables under roof systems and decks
The following bulletin provides guidance on the application BC Electrical Code: Sections 2 & 12.
Topic: Roofing and electrical equipment
The Roofing Contractors Association of British Columbia (RCABC) has reported a recent increase in occurrences of electrical raceways and cables being installed within, or adjacent to the underside of, roof systems or roof decks. Cables and raceways, installed in proximity to roof systems or roof decks may be subject to mechanical damage during roof installation or repairs. Nails and screws, used to penetrate the roofing from the top during the roof installation process, could easily penetrate electrical cables and raceways installed within or adjacent to roof systems or roof decks. This could result in electrical shock or fire hazards.
The figure below shows a typical roofing system and how a screw can easily penetrate electrical equipment (a conduit, in this example):
Diagram provided courtesy of Roofing Contractors Association of British Columbia
- Rule 2-032 Damage and Interference requires that no person shall cause damage to an electrical installation or components thereof, except when it is necessary to disconnect or move components of an electrical installation during alterations or repairs; it is the responsibility of the person carrying out the alterations or repairs to ensure the electrical installation is restored to a safe operating condition.
Persons performing roof installation, alteration, or repair must ensure that they have identified and located all electrical equipment installed within or adjacent to the roof system or roof deck before carrying out their work. Mapping out conduit and cable locations, disconnection of electrical power within work areas, and safe work practices will reduce or prevent electrical fire and shock hazards. Electrical contractors should ensure that electrical drawings accurately show locations of electrical raceways and conduits upon completion of their work. Alteration or relocation of electrical conduits, raceways, and equipment may only be performed under a valid electrical permit.
- Rule 2- 200 General requires that electrical equipment must be protected and guarded against mechanical damage or other damage to which it is liable to be exposed.
The RCABC recommends that electrical raceways and cables can be protected from mechanical damage by ensuring that:
a) no electrical equipment is installed closer than 38mm (1.5”) as measured from the nearest point of the roofing system or deck; or
b) the electrical equipment is protected from mechanical injury by a steel plate not less than 5mm (3/16 inch) thick and extending at least 38mm (1-1/2 inches) beyond the electrical equipment on each side.
Provincial Safety Manager, Electrical
References: BC Electrical Code