On 16/02/2013 00:50, Lobster wrote:
On 15/02/2013 22:29, John Rumm wrote:
On 15/02/2013 20:15, mike wrote:
Just came to fit some socket outlets from Toolstation and realised the
faceplate screws aren't connected to earth.

They're the top ones in this pic:

http://i46.tinypic.com/9glo1z.jpg

Older MK version with earth connection is below.


I thought all sockets followed the MK pattern with the result that
using either the earth connection on the faceplate or the earth
connection in the back box would result in everything being connected
to earth.

As you have seen, not always...

Don't think I've ever seen them before - I always assumed the earthed
screw holes were mandatory

But if someone made the earth connection to the back box on
the Toolstation version, any connected appliance (double insulation
and plastic earth prongs aside) wouldn't be earthed. Is that right?

No, because the circuit earth wires will always be connected to the
earth terminal on the socket face plate. You would not simply terminate
the circuit earth wires on the backbox and rely on that to make an earth
connection to the backbox.

With a "normal" socket that has earthed screw holes the reverse
situation is allowable - i.e. you can re;y on them to earth the backbox
(assuming it has at least one fixed tag), however good practice would
suggest adding a separate fly lead between circuit terminal and the
earth terminal on the back box.

So, if you have sockets with earthed screw holes does that mean you
actually don't need the fly lead twixt socket and backbox? I thought it
must be a belt-and-braces thing or something, but didn't think you could
just do away with the flylead?

IIUC, so long as the box has at least one fixed lug, then you can do
without the discrete fly lead.


--
Cheers,

John.

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