Trenches more than 1.30 metres deep and no more than two-thirds the width of the trench must be shored, braced or propped if their walls are vertical or substantially vertical.
The walls of other trenches, as well as those of excavations or mounds, must be designed to prevent landslides, taking into account the nature and condition of the soil. If this is not possible, shoring, struts or props appropriate to the nature and condition of the soil will be installed. These protective measures shall not be reduced or eliminated when the ground is frozen.
These protective measures shall be taken before any worker or employer descends into the excavation for any work other than that of installing the protective devices.
When no one is required to descend into the excavation, areas close to the edge of the excavation which could present a danger to workers are clearly demarcated and visibly signposted.