The striking element has a hemispherical face of radius 10mm made of hardwood, polyamide or similar material weighing 0.15kg. It is rigidly fixed to the lower end of a steel tube with an external diameter of 9mm and thickness 0.5mm which is pivoted at its upper end in such a way that it swings only in the vertical plane of the axis of the striking element. The axis of the pivot is 1m above the axis of the striking element. The design of apparatus is such that a force between 1.0 N and 2.0 N has to be applied to the face of the hammer to maintain the pendulum in a horizontal position.
The appliance is held against a solid wall of bricks, concrete or the like, and the test apparatus is so arranged that the pivot of the pendulum is vertically above the point of impact of the hammer. The striking element is then allowed to fall form such a height of 250 mm. Three such blows are applied to every part of the enclosure which is likely to be weak, including handles, levers and the like, but excluding signal lamps and their covers if these do not protrude from the enclosure by more than 3mm or have a surface not exceeding 3 cm2. Lamps within an appliance and their covers are tested only if they are likely to be damaged in normal use.