Earthing a mounting box (flying earth)

[EddieJT]

When is it necessary in a socket to run an earth from the socekt earth terminal to the metal mounting box. I thought it was only when the actual socket fitting was metal?

I have just wired all of my new plastic sockets without this earth connection to mounting box, but have just read that if using metal mounting boxes they should have an earth run to them regardless of plastic socket fitting.

Can someone put me straight please?

 

[Adam_151]

Your socket outlets will be earthed by the earth conductors connected to them, whether the plates are metal or plastic, if the socket is screwed to a metal box, then this needs a connection to earth, now if this is a flush mounting box with at least one fixed lug, then its considered earthed through the screws, now if its a surface m/c knockout box, or it has no fixed lugs then you'll have to put a flylead in. Some consider it good practice to put the flylead on recessed ones witha fixed lug as well

Not that doesn't work the other way, you can NOT connect the earths in the cable to the box terminal and earth the plate through the screws... you'd have to put a link in... this also applies where steel conduit, swa or MICC is used as the cpc... you have to put the link in