It is an equipment: ‘
(a) having an enclosure capable of :
(i) withstanding an explosion within it of a specified flammable gas or vapor, and
(ii) preventing the ignition of the specified flammable gas or vapor in the atmosphere surrounding the enclosure by the sparks, flashes or explosion of the gas or vapor within.
(b) that operates at such an external temperature that a surrounding flammable atmosphere will not be ignited. Where explosion-proof equipment is required by these rules, equipment is certified as being flameproof by any accepted authority.