Levels of hazard probability

Ref. 39 suggests an initial qualitative hazards analysis early in systems design, with only general levels of hazard probabilities identified, in addition to severity categories. An example of such a qualitative ranking from Ref. 39 appears in Table V. 

Likelihood of Hazard. The NEC recognizes two distinct levels of hazard probability. Division 1 denotes an environment in which the probability exists that sufficient levels of the hazardous element may always exist, under normal operating condition, as to warrant extreme protections. Whereas, Division 2 denotes an environment where the probability for sufficient levels of the hazardous element to exist, under normal operating conditions, is less likely, and therefore, the extreme protection is not justifiable. Further areas adjacent to Division 1 areas can often constitute classification as Division 2 environments. 

Design for Minimum Risk The system safety order of precedence dictates that, from the first stages of product or system design, the system should be designed for the elimination of hazards, if possible. Unfortunately, in the real world, this is not always practical or feasible. If an identified hazard cannot be eliminated, then the risk associated with it should be reduced to an acceptable level of hazard probability through design selection. 

---

See also in sourсe #XX -- [ ]

---