Molded-Case Circuit Breakers - Is There Danger in Present Rating Methodology?

Molded case circuit breakers have proven to be quite versatile, with increasing capabilities being designed into new products. Interrupting capacity and adjustability of tripping times and magnitude are constantly being improved. This proliferation has developed so widely that applications may appear much simpler than actual and may be marginal even if executed in accordance with certified tests and standards. Examples of less publicized facts about the application of molded case circuit breakers are described. The possibility of the user having unsafe results is inescapable. A conclusion is reached that issues of safety should receive more open discussions so that standards can be improved. It also appears that users have not been advised of the risks involved in order to enable an economic justification study to be made. A suggestion is made that the IEEE develop an intensive educational program which would result in certification of engineers involved with protection.