FAQs: Circuit Breaker Boots

Thermal and magnetic/hydraulic circuit breakers are precision controls components offered in a variety of actuating styles; single and multiple lever, pushbutton, rocker and toggle (illuminated & non-illuminated). In many applications they are exposed to harsh environmental conditions that could shorten their actuation life and affect reliability. Each Intended for different applications, each having different environmental sealing challenges. Most (lever & pushbutton) require the ability of the operator to see the position (status) of the actuator/LED. Matching sealing boots (covers) must be transparent, and remain so for the life of the breaker. These boots basically fall into two mounting categories -- front-of-panel and back-of-panel styles. Standard toggle boots can be opaque. The skills necessary to design and build a sealing boot that is rated IP66/68 are quite different for environmental protection as opposed to the manufacture of the breaker itself, whether for military or commercial applications.

For example, any mounting hardware used in association with lever style breaker seals has to incorporate its own high-pressure sealing system making a positive sealing contribution. In fact, APM invented the first self-sealing screw (SEELSKREW®) for circuit breaker boot-flange mounting which seals to 20,000psi. Highly flexible clear silicon rubber, which is most frequently used for the enclosure portion, has to be of correct durometer and geometry to address varied tactile and ergonomic considerations. And, must remain clear for the rated life of the sealing boot (cover) and NOT turn yellow as ordinary silicone rubber does with age and UV exposure. To insure reliable life-time see-through performance, APM formulated a silicon rubber composition trade marked RUBRGLAS®. This exclusive material can only be found on HEXSEAL® & E-SEEL® circuit breakers sealing boot enclosures. But sometimes this dynamic is not enough and addition tactile operating force is required. Many of our boots feature a carefully designed internal patented “trigger” that extends the operator’s finger pressure. APM HEXSEAL® and E-SEEL® boots are ideal mates to the very best breakers available today. That’s why the vast majority of breaker manufacturers recommend our UL Recognized Component HEXSEAL® and E-SEEL® boots.

APM has been satisfying their customers’ environmental protection needs for more than 60 years with the world’s largest selection of sealing boots. APM circuit breaker boots have been installed on many thousands of electrical/power supply systems in a wide variety of marine equipment from submarines to pleasure and commercial military surface vessels, aircraft and support equipment, military land equipment of all kinds, medical, and control panels of a variety of field maintenance and repair equipment, to name just a few of many applications.

For more details see our Circuit Breaker Sealing Boot catalog PDF in the literature section of this website.