Apologies - not having access to BS EN 60320 I can't see the context of its definitions, so I'm having difficulty commenting on that bit. While I can see that the usual female IEC connector on the load end of a flex would certainly be a coupler (or "connector" in BS 7671 definition terms), I still can't see how the panel mount version (connected to "fixed" wiring and intended to accept a C14 plug on the supply end of the flex) would fit the same BS 7671 definitions. Looking at it the the way around, trailing 13A sockets come under BS 1363 - the standard for socket outlets, but surely in BS 7671 terms they're couplers/connectors, rather than socket outlets, when connected on the end of a flex rather than fixed wiring.

I think the title of the standard is sufficient.

I do see your point about BS EN 60320 items not being listed as being acceptable socket types - but again that of itself doesn't say to me it's not a socket.

No, but it does mean you shouldn't really be specifying it if it is.

If I stuck a schuko socket on a wall, I think the usual conclusion would be that it was a departure from BS 7671 (which may or may not be justifiable under 133) rather than it needed to be given the name of a different kind of accessory.

But the standard for Shuko socket-outlets are "socket-outlets". But yes, might be acceptable for, say, a factory test area where export appliances are made, as it would be a safer option than using a UK or Industrial socket-outlet in that particular case, but in "domestic and similar" situations, the Plugs and Sockets (Safety) Regulations apply, plus the requirement for shuttered outlets in that type of usage.

So far we seem to be saying that, in the picture of the PDU above, that the right hand four "outlets" are sockets as far as BS 7671 is concerned, and so require 30mA RCD protection (unless a risk assessment concludes otherwise), but the eight "outlets" on the left, are deemed not to be socket outlets, so have no such requirements - even though they're likely to be used in exactly the same way. That's a conclusion I'm not entirely comfortable with.

But this is precisely why I asked the specific question whether you were advocating 30 mA RCD protection for couplers as well!

In fact, I agree it's a difficult situation to grasp, but at the end of the day the Reg exists for "couplers" separate to "socket-outlets", and I can't see the difference between "appliance outlet" and "free outlet" in the context of a cable coupler.

So, the question - should couplers be included in 411.3.3 ? I sort of think you're saying they should be.

13A Socket -> Plug -> Flex -> Appliance - OK (30mA RCD protection required at or before socket)

Agreed. 411.3.3

FCU -> Flex -> Appliance (might be fixed or hand-held) (no RCD requirement)

Yes, but not quite, 411.3.3 (ii) may apply in some cases?

FCU -> Flex -> BS 1363 outlet (as in the pendant socket mentioned before, or a autorewind reel with a trailing socket on the end of the flex) - apparently a connector rather than a socket, so no RCD requirement?

I think this is a socket-outlet, or an accessory with socket-outlets, so I think 411.3.3 (i) applies.

FCU -> Flex -> BS EN 60320 connector - similarly, no RCD requirement?

Unless 411.3.3 (ii) applies, I believe so. This is definitely a cable coupler, and these do not appear to be covered by 411.3.3 (i)

FCU -> BS EN 60320 panel outlet (directly hard-wired, no flex) - not permitted?

Disagree. If the panel outlet complies with BS 5733 and has a connector block for "hard wiring", then this would comply with BS 7671, and I don't think it needs an RCD unless 411.3.3 (ii) applies, as there are no socket-outlets, just couplers.

Apologies - not having access to BS EN 60320 I can't see the context of its definitions, so I'm having difficulty commenting on that bit. While I can see that the usual female IEC connector on the load end of a flex would certainly be a coupler (or "connector" in BS 7671 definition terms), I still can't see how the panel mount version (connected to "fixed" wiring and intended to accept a C14 plug on the supply end of the flex) would fit the same BS 7671 definitions. Looking at it the the way around, trailing 13A sockets come under BS 1363 - the standard for socket outlets, but surely in BS 7671 terms they're couplers/connectors, rather than socket outlets, when connected on the end of a flex rather than fixed wiring.

I think the title of the standard is sufficient.

I do see your point about BS EN 60320 items not being listed as being acceptable socket types - but again that of itself doesn't say to me it's not a socket.

No, but it does mean you shouldn't really be specifying it if it is.

If I stuck a schuko socket on a wall, I think the usual conclusion would be that it was a departure from BS 7671 (which may or may not be justifiable under 133) rather than it needed to be given the name of a different kind of accessory.

But the standard for Shuko socket-outlets are "socket-outlets". But yes, might be acceptable for, say, a factory test area where export appliances are made, as it would be a safer option than using a UK or Industrial socket-outlet in that particular case, but in "domestic and similar" situations, the Plugs and Sockets (Safety) Regulations apply, plus the requirement for shuttered outlets in that type of usage.

So far we seem to be saying that, in the picture of the PDU above, that the right hand four "outlets" are sockets as far as BS 7671 is concerned, and so require 30mA RCD protection (unless a risk assessment concludes otherwise), but the eight "outlets" on the left, are deemed not to be socket outlets, so have no such requirements - even though they're likely to be used in exactly the same way. That's a conclusion I'm not entirely comfortable with.

But this is precisely why I asked the specific question whether you were advocating 30 mA RCD protection for couplers as well!

In fact, I agree it's a difficult situation to grasp, but at the end of the day the Reg exists for "couplers" separate to "socket-outlets", and I can't see the difference between "appliance outlet" and "free outlet" in the context of a cable coupler.

So, the question - should couplers be included in 411.3.3 ? I sort of think you're saying they should be.

13A Socket -> Plug -> Flex -> Appliance - OK (30mA RCD protection required at or before socket)

Agreed. 411.3.3

FCU -> Flex -> Appliance (might be fixed or hand-held) (no RCD requirement)

Yes, but not quite, 411.3.3 (ii) may apply in some cases?

FCU -> Flex -> BS 1363 outlet (as in the pendant socket mentioned before, or a autorewind reel with a trailing socket on the end of the flex) - apparently a connector rather than a socket, so no RCD requirement?

I think this is a socket-outlet, or an accessory with socket-outlets, so I think 411.3.3 (i) applies.

FCU -> Flex -> BS EN 60320 connector - similarly, no RCD requirement?

Unless 411.3.3 (ii) applies, I believe so. This is definitely a cable coupler, and these do not appear to be covered by 411.3.3 (i)

FCU -> BS EN 60320 panel outlet (directly hard-wired, no flex) - not permitted?

Disagree. If the panel outlet complies with BS 5733 and has a connector block for "hard wiring", then this would comply with BS 7671, and I don't think it needs an RCD unless 411.3.3 (ii) applies, as there are no socket-outlets, just couplers.