Regulation 27

into high tensile steel, steel hardened by heat treatment, cast iron or any other substance of a hardness that a projectile is not designed to penetrate;

into tiles, terracotta, glazed brick, glass, marble, granite, thin slate or any other substance that is readily shattered;

into concrete or reinforced concrete, where any initial trial has shown that the aggregate is of such hardness, or the reinforcing is so positioned, that the use of the tool is unsafe;

so close to the edge of any substance, or to any hole in the substance, as either to risk cracking or breaking the substance or to risk the escape of the projectile from the substance;

within 15 millimetres, in the case of a direct acting tool, or within 10 millimetres, in the case of an indirect acting tool, of the edge of any exposed steel reinforcement; or

into any brick, concrete or similar substance that is within 75 millimetres, in the case of a direct acting tool, or within 50 millimetres, in the case of an indirect acting tool, of an edge of a structure of which the brick, concrete or substance forms a part.