4. A working platform shall—
(a)be suitable and of sufficient strength and rigidity for the purpose or purposes for which it is intended to be used or is being used;
(b)be so erected and used as to ensure that its components do not become accidentally displaced so as to endanger any person;
(c)when altered or modified, be so altered or modified as to ensure that it remains stable; and
(d)be dismantled in such a way as to prevent accidental displacement.