In article ,
"Ellis Greensitt" writes:
If a metal backbox was supplied with a preinstalled piece of earth wire onto
the earth terminal, how much time do you think you could save 2nd fixing a
house ?

Sparks never earth back boxes, so it would add time to either connect
it or cut the wire off, neither of which they would otherwise do.
Also, it's another dangly bit to get in the plasterer's way.

Some conciensous DIY's earth back boxes, but their time is free to a
first approximation, so the time saved isn't worth anything.

--
Andrew Gabriel