I. INTRODUCTION
A number of presentations from past Institute of Electrical and
Electronics Engineers (IEEE) Conferences and Electrical
Safety Workshops have focused on the reliability and
maintainability of molded case circuit breakers as a factor in
developing a credible facility safety program. Most certainly,
proper maintenance of any electrical product is necessary to
assure reliable operation. However, past assertions such as
“Several studies have revealed that circuit breakers that were
not maintained within a period of five years have a 50%
probability of failure” [1] and “If a breaker has not been
operated within as little as 6 months, it should be removed
from service and manually exercised” [2] and “Maintenance of
molded case circuit breakers is limited to proper mechanical
mounting, electrical connections and periodic manual
operation” [3] tend to be misleading. In actual practice, circuit
breakers subjected to interruption of high level faults, harsh
environments and lack of maintenance will certainly need to
be replaced before their performance is compromised. The
question is how does one know when these breakers should
be replaced?
Over the past several years an integrated paper mill in
Longview WA has used innovative preventive maintenance
diagnostic methods to confirm the integrity of molded case
circuit breakers (MCCBs). Facility maintenance processes
and testing methods have resulted in sound decisions to
remove breakers from service during rotational outages based
upon thermal imaging from routine infrared (IR) scans.