(a) is at least 50 mm thick by 250 mm wide,

(b) has a span not longer than 3 m,

(c) extends at least 150 mm and not more than 300 mm beyond a supporting member,

(d) is laid flat with an overlap of 300 mm with another plank, with the centre of the overlap directly over a bearer, and

(e) is secured to prevent movement in any direction that may create a danger to an employee.