7 Safe system of work
1 The compressed air contractor shall ensure that a person shall not work in compressed air or enter or leave compressed air except in accordance with a system of work which, so far as is reasonably practicable, is safe and without risks to health.
2 The compressed air contractor shall ensure that a sufficient number of competent persons are present on site to supervise the execution of work in compressed air at all times when such work is being carried out and, in the case of such work undertaken at a pressure of 0·7 bar or above, for 24 hours thereafter.
3 Without prejudice to the generality of paragraph (1), the compressed air contractor shall ensure that all shafts or tunnels under his control to which he applies compressed air and the ground surrounding them are capable of withstanding the loads arising from the application of compressed air.