I have no clue, but maybe this site can help: http://en.wikipedia.org/wiki/Circuit_breaker

it mentions both live and dead tank circuit breaker and has a corresponding German link

OT

Next time if you could just check [Elec.] or whatever ...

I was all set to learn a nice new slang word for a morgue or something. (-:

... and, as you know what it means, explain it:

"Circuit breakers can be classified as live tank, where the enclosure that contains the breaking mechanism is at line potential, or dead tank with the enclosure at earth potential."

Source: above Wiki-article . . .

Ich rate mal:

live tank: 'spannungsführendes/potentialbehaftetes Gehäuse'
dead tank: 'spannungsloses/potentialfreies Gehäuse' ? . . .

... neue Schreibweise: 'potenzial...' . . .