PART XII POWERED MOBILE EQUIPMENT — Securing elevated loads
270
(1) An elevated load, part, extension or machine, shall not be left unattended by an operator unless it has been immobilized and secured against inadvertent movement.
270(2)
Where a worker is required to work beneath an elevated part of mobile equipment, the elevated part shall be securely blocked.
270(3)
An hydraulic or pneumatic jack shall not be used for blocking unless it has been fitted with a device to prevent collapse in the event of loss of hydraulic or pneumatic pressure.
Not legal advice. Verify the cited article against the signed agreement.