Insulated-case circuit breakers are molded-case breakers using glassreinforced
insulating material for increased dielectric strength. In addition,
they have push-to-open button, rotary-operated low-torque handles with
independent spring-charged mechanism providing quick-make, quickbreak
protection. A choice of various automatic trip units is available in the
insulated-case breakers. Continuous current ratings range up to 4000 A
with interrupting capacities through 200,000 A. The principal differences
between insulated-case breakers and heavy-duty power circuit breakers
are cost, physical size, and ease of maintenance. Insulated-case breakers are
not designed with easy troubleshooting or repairs as the principal feature;
whereas, draw-out power circuit breakers are. To partially compensate for
this drawback, many manufacturers now offer a variety of accessories for
insulated-case breakers that can duplicate the features of their more
expensive counterparts. Nevertheless, insulated-case breakers are generally
suited to light industry or commercial buildings where frequent or
numerous operations are not expected.