Conducting Materials and Methods for Grounding Metal Bodies
49. (1) Metal roofs shall be provided with air-terminals as prescribed in section 26. R.R.O. 1990, Reg. 712, s. 49 (1). (2) A conductor shall be coursed over a metal roof in the same manner as over a roof other than of metal, but coursing is not required where a metal roof is grounded by conductors attached to the eaves or to grounded metal siding if the roof and siding are in good electrical contact or the eaves and siding are interconnected in at least three places at intervals not exceeding forty feet. R.R.O. 1990, Reg. 712, s. 49 (2). (3) A metal-roof slope or interconnected metal-roof slopes, when grounded through conductors attached to the eaves, shall have two down-conductors if the length of the eaves or interconnected eaves exceeds thirty feet and three down-conductors if the length exceeds 100 feet. R.R.O. 1990, Reg. 712, s. 49 (3). (4) Where groundings are connected to metal siding only, they shall be installed at the main corners of the building or structure and at intervals not exceeding 100 feet measured horizontally along the metal siding. R.R.O. 1990, Reg. 712, s. 49 (4). (5) Connections of down-conductors to metal eaves or metal siding shall be made, (a) if the down-conductors are cable, by means of metal plates, (i) shaped to fit over and in tight contact with at least three inches of the cable, (ii) secured in tight contact with at least nine square inches of the eaves or siding by means of six bolts, rivets or screws, and (iii) with the ends of the wires turned back over the edge of the metal plate; or (b) if the down conductors are strap, by securing at least nine square inches of the strap in tight contact with the eaves or siding by means of four bolts, rivets or screws. R.R.O. 1990, Reg. 712, s. 49 (5). (6) Connections of conductors, other than down-conductors, to metal roofs and metal siding shall be made, (a) if the conductor is cable, by means of metal plates, (i) shaped to fit over and in tight contact with at least two inches of the cable, (ii) secured in tight contact with at least six square inches of the eaves or siding by means of four bolts, rivets or screws, and (iii) with the ends of the wires turned back over the edge of the metal plate; or (b) if the conductor is strap, by securing at least six square inches of the strap in tight contact with the eaves or siding by means of three bolts, rivets or screws. R.R.O. 1990, Reg. 712, s. 49 (6). (7) Where, (a) a copper conductor is coursed over an aluminum roof or siding; (b) an aluminum conductor is coursed over a copper roof or siding; (c) a copper air-terminal support is attached to an aluminum roof; or (d) an aluminum air-terminal support is attached to a copper roof, the copper and aluminum shall be separated under all fasteners and air-terminal supports by sheet lead of at least one-sixteenth of an inch in thickness or by galvanized iron of at least 28-gauge. R.R.O. 1990, Reg. 712, s. 49 (7). (8) Where, (a) a copper air-terminal is attached to an aluminum roof; (b) an aluminum air-terminal is attached to a copper roof; (c) a system is grounded by attaching copper conductors to an aluminum roof at the eaves or siding; or (d) a system is grounded by attaching aluminum conductors to a copper roof at the eaves or siding, the copper and aluminum shall be separated by galvanized iron of at least 28-gauge. R.R.O. 1990, Reg. 712, s. 49 (8).