Weatherproof/External Socket

[Hysteresis]

I purchased and installed an external Double socket from Screwfix. The back box has two Earth connections. When checking closely these earth connection have NO continuity with the Earth terminals on the sockets. I thought initially that continuity would be established when the sockets were installed in the back box via the location screws, however when checking the earth continuity I found that not to be the case. I reconnected the Earth wire from the supply cable directly to the socket earth terminal to establish continuity.
The question is, did I do right? I can see no reason for the Back Box terminals to exist as using them does not give an earth to the Sockets. Maybe the IEE Regs demand that NO Earth should be made for the External sockets as items like garden electrical equipment are usually double insulated and not earthed but of course I may want to use domestic equipment on a temporary basis which are not double insulated and as such require an Earth continuity for Safety reasons.
I would welcome comments from some IEE Regs knowledgable Sparky.
My thinking is that the design of having an earth terminal which serves no earthing purpose is suspect and providing it for use could be dangerous in that it provides an Earth terminal which does not earth the sockets if used.

 

[Colin Brenton]

The earth terminal in the box is there so that the box can be earthed, as well as the socket.

Just run your circuit earth to the socket, and then a wire link from the socket earth terminal to the box.

 

[CACKATALLTRADES]

The earth terminal in the box is there so that the box can be earthed, as well as the socket.

Just run your circuit earth to the socket, and then a wire link from the socket earth terminal to the box.

What purpose is served by earthing a plastic back box other than as a means of earthing the attached equipment?

 

[securespark]

Many non metallic boxes and pattresses have earth terminals in. You don't have to use them, they are there if you need to.

 

[SUNRAY]

The plastic enclosures are used for different purposes and it is likely that not all accessories fitted in the enclosure will have a use for an earth or even have an earth terminal. An all plastic switch for example.

Another possibility is there may be more than one earth, such as an earth rod, in which case the earth in the supply cable may be terminated in a terminal and completely isolated from the accessory.

In this instance you may add a link wire from the socket - as Colin says - but there is little point, or just ignore the boxes earth terminal.

 

[Hysteresis]

Thanks for all of your replies. My concerns were only that maybe the IEE Regs for some obscure reason may have stated that external sockets should not be earthed. It did not sound correct but the IEE Regs sometimes come up with weird regs which seem a little odd.
My earthing of the socket terminal is, as I thought, the correct installation and I will just ignore the Back Box Earth Terminal as superfluous to requirements.
Thanks everyone for your comments.