Sch 1 para 38 General requirements
(1) Protective systems must be dimensioned in such a way as to reduce the effects of an explosion to a sufficient level of safety. (2) Protective systems must be designed and capable of being positioned in such a way that explosions are prevented from spreading through dangerous chain reactions or flashover and incipient explosions do not become detonations. (3) In the event of a power failure, protective systems must retain their capacity to function for a period sufficient to avoid a dangerous situation. (4) Protective systems must not fail due to outside interference.