Proof in the form

1 intrinsically safe "i" (intrinsically safe electrical equipment and its associated equipment) intrinsically safe circuits:
The specified test conditions, or required to work under fault conditions and thermal effects resulting spark can not ignite an explosive gas or vapor prescribed circuit.
Intrinsically safe  mcb circuit breaker  equipment: All circuit is intrinsically safe electrical equipment.
Intrinsically safe equipment and associated equipment ia and intrinsically safe part is divided into ib:
¨ ia: + work + a failure of any combination of two failures were not caused by the fire of electrical equipment.
¨ ib: work + a fault condition does not cause ignition of intrinsically safe electrical equipment.
Thus ia ib grade level higher than
Associated equipment:  electri cenergy meter  safe circuits and non-intrinsically safe circuits, and the structure is non-intrinsically safe circuits intrinsically safe circuits can not adversely  circuit breakers  the electrical equipment.
2 flameproof "d" flameproof enclosure with electrical equipment.
Has entered the interior of the housing can withstand the combustible mixture from an internal explosion damage, and on the housing does not ignite any joint or the holes of one or more gases or vapors formed by the external electrical equipment explosive environment shell.
3. Increased safety
4. Oil-filled
5. Sand filled
6. Encapsulation
7. Compound