Siemens ground fault equipment protection circuit breakers provide protection of equipment from damaging line-to-ground fault current and de-energizes the circuit for all ungrounded conductors of the circuit. Siemens strongly recommends against the use of "used" breakers. The installation of used breakers in a Siemens panel will void the warranty on the panel. Siemens does not sell used breakers and has not approved any 3rd party sellers to do so.