104. An employer shall ensure that a working platform is—

(a) suitable and of sufficient strength and rigidity for the purpose for which it is intended to be used or is being used,

(b) so erected and used as to ensure that its components do not become accidentally displaced so as to endanger any employee,

(c) when altered or modified, so altered or modified as to ensure that it remains stable,

(d) where it has moving parts, prevented by appropriate devices from moving inadvertently during work at height, and

(e) dismantled in such a way as to prevent accidental displacement.