German term (edited): Freischalten der Anlage / gegen Wiedereinschalten sichern

See
http://www.hse.gov.uk/electricity/faq.htm
http://www.industrialsafetytalk.com/news/hea/hea165.html
and

http://www.lancs.ac.uk/depts/safety/section.12/body.htm

"Means of cutting off the supply and for isolation (Regulation 12)

Provision must be made within an installation for cutting off the supply and ***isolating*** it. It should be noted that whilst "cutting off the supply" relates to switching, ***"isolation"*** refers to the disconnection of the supply and the prevention of ***inadvertent reconnection***."

--------------------------------------------------
Note added at 37 mins (2006-03-16 08:47:01 GMT)
--------------------------------------------------

to prevent inadvertent reconnection -> to safeguard against inadvertent reconnection - see example @

http://unionsafe.labor.net.au/hazards/1074833741320.html

"Isolation

The electrical equipment to be worked on must be isolated from all sources of supply. Where isolation is effected at a removable or rack-out circuit-breaker or combined fuse switch, it must be racked out or removed to provide a visible break for isolation verification, then locked open and danger tagged. When returning after being absent from the immediate work area, it is imperative that checks and tests are carried out to ensure that the electrical equipment being worked on is still isolated when you return, ***to safeguard against inadvertent reconnection*** by another person."

--------------------------------------------------
Note added at 1 hr (2006-03-16 09:54:29 GMT)
--------------------------------------------------

"(equipment) isolation" beinhaltet in der Tat mehr als nur "spannungsfrei machen/schalten" (also die Stromversorgung unterbrechen), nämlich die Trennung von *sämtlichen* vorhandenen Energiequellen (bzgl. die Ableitung von Energie aus der Anlage). "Freischalten/Freischaltung (von Anlagen)" wird aber auch genau in diesem umfassenden Sinne im Deutschen verwendet.