Stefek Zaba wrote
| A better form of trailing socket from that point of view is a metalclad
| socket, with a cable gland used to provide proper strain relief. Being
| finicky, they're not really meant to be bashed about on their own -
| it's possible one of the round blanking discs could fall out if
| subjected to rough handling, exposing the innards to a careless finger.

It is possible to obtain metalclad back boxes without knockouts, for use in
schools etc where vandalism is a problem. Obviously, it would need to be
20mm drilled for the cable gland.

Owain