On 13/05/2018 13:24, Harry Bloomfield wrote:
It happens that Robin formulated :
Yes, but the context of the text I quoted was a *different* point -
viz "I have never understood why *wholly* [emphasis added] plastic
earth pins are not allowed."

I would imagine that is because if a brass pin is actually needed, the
partially sleeved ones have more of a tendency to break. On something
which requires an earth, the last thing you want is an internally broken
earth pin, which might still allow you to plug the plug into a socket.

Plastic earth pins are allowed on the likes of phone chargers, even
folding ones. There, just to push the shields out of the way.

They tend to break off, then you have to plug the device into the same
socket and nothing else there. I don't know whether they are still made,
but you could get 13A sockets which didn't rely on the earth pin to open
the shutter - you just had to insert pins into both line and neutral
simultaneously. That's a better idea as devices that don't require an
earth just need two pins. Our 13A plugs and sockets are rather a rubbish
design.

--
Max Demian