Even thoughcircuit breakers can be very reliable, they tend to gather dirt, moisture, andcontaminants on the poles and on the exterior surface of the interrupter, whichmay cause insecurity during operation. Once the air finds its way into theinterrupter and leakage starts to appear, the vacuum bottle becomes unreliable.

In some westerncountries, people test the vacuum switch with DC voltage test and leakage currenttest method. For instance, the circuit breaker vacuum bottle tester.

InChina, peopletest the vacuum switch with AC hipot tester and vacuum degree tester.