Special testprobe to perform a PE-test safely en quick. The moving testtip is attached to a micro switch. The testcurrent is only than switched on after a good secure contact has been established. Also the testcurrent is switched of before the contact is broken. Switching on and of the testcurrent is done on the zero crossing. This avoids damage to your product due to arcing. 

Because of the separate sense wire, the wiring resistance is compensated up to the measuring tip. This allways guarantees an accurate measurement.