Explosion-proof equipment

Electrical apparatus (such as compressors, motors, and switches) designed to contain explosions or flames produced within them (due to arcs, sparks, or flashes) without igniting the surrounding (external) flammable gases or vapors
Reference: Chemical Process Safety – Fundamentals with Applications, 2nd Ed., Daniel A. Crowl/Joseph F. Louvar
Any electrical equipment designed to be installed, used or introduced in areas where explosive atmosphere can be present. It must have a declaration of conformity adequate to the type of zone and must be properly CE marked.
Reference: S2S (safety to safety website)
Science/Flammability/Prevention Design