Totally enclosed low-voltage switchgear, in its present form, began to gain
acceptance through the 1950s. The manufacturers of the time marketed threepole
circuit breakers and their enclosures as equipment that was safer for the
user’s personnel, more reliable, and as having advantages over fuses; namely,
prevention of single phasing on three-phase AC systems. Today, low-voltage
switchgear takes on many specialized forms and functions that combine metering,
monitoring, control, protection, and distribution. Major manufacturer