The mechanical construction of JW COS is rugged and strong. It is designed to withstand the interruption forces of heavy fault current and the typically closing by operator.

The upper contact and the hinge are attached to husky steel supports, Both supports and the mounting insert are permanently anchored into cavities in the insulator with inorganic cement, which does not deteriorate or absorb moisture. The cement will not shrink to loosen the inserts nor swell to put stress on the insert cavities of the porcelain.

The fuse tube is held at the upper contact by a self-aligning spring loaded detent type latch. The detent type is heavily silver clad and features embossed surfaces for built-in wiping action result-ing in minimum electrical resistance between the upper contact and the silver-clad fuse tube cap.

Theses specially designed high-pressure upper and lower contacts, featuring built-in wiping action, assure superb current transfer even after the contacts have been exposed to the atmo-sphere for an extended period of time.