S-2.1, r. 14 - Regulation respecting occupational health and safety in mines

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515. In a circuit whose voltage exceeds 300 V to ground, a disconnecting switch with visible air-break contacts shall be connected between a control device and the source of electric power, unless the control device makes a visible air-break on each phase of the circuit.
For the purposes of this section, “visible break” means that the separation between the fixed and mobile current-carrying parts of a switch or a disconnecting break than can be visually checked.
O.C. 213-93, s. 515.