I don't see an obvious get-out clause for 421.1.7 like there is for 411.3.3. Maybe IT equipment (being generally free of a.c. motors and frequently operated switching devices) isn't particularly prone to nuisance trip AFDDs,but I share your concern.

I guess another option would be to hard-wire the rack (e.g. replace the socket with a rotary isolator), make it a 3-phase socket (421.1.7 only applies to single phase) - it's fine just to pick up one phase at the plug if that all that's needed, or perhaps replace the fixed socket with a box, a short length of dangling flex and a BS EN 60309 connector ... by BS 7671 definitions that would seem to be classed as connector rather than a socket outlet (but I can see a debate about that).

   - Andy.

AJJewsbury said:

BS EN 60309 connector .

BS EN IEC 60309 outlets are either 'fixed socket-outlet' or 'portable socket-outlet' as defined in the standard, so not a "connector".

Plugs to the standard are either a "plug" or an "appliance inlet".

So, I don't think that is valid, as far as BS 7671 goes, it's still a socket-outlet.

BS EN IEC 60320 might offer an alternative, though ... these are either inlets or outlet 'couplers'... just a thought.


Pedantry aside, surely this is one for the fire risk assessment of the premises, rather than a discussion on how to avoid conformity alone ... and to involve the competent person responsible for that?

BS EN IEC 60309 outlets are either 'fixed socket-outlet' or 'portable socket-outlet' as defined in the standard, so not a "connector".

But when reading BS 7671 surely it's BS 7671 definitions we follow - and BS 7671 defines what it considers a socket outlet to be 'intended to be installed with the fixed wiring'.

   - Andy.

AJJewsbury said:

But when reading BS 7671 surely it's BS 7671 definitions we follow - and BS 7671 defines what it considers a socket outlet to be 'intended to be installed with the fixed wiring'.

What is 'fixed wiring' ?

Flexible cabling can be used for 'fixed wiring'.

To my mind, I'm not sure that attempting to 'fudge' the requirements is the right approach.

gkenyon said:

What is 'fixed wiring' ?

Fair comment. A flex, unclipped, but hard wired at one end... the far end is "movable" in the same way an hand held appliance could be moved while still plugged in, but not in the sense of being transportable. Certainly open to interpretation. In these times where some entire installations could consist of flexes plugged together on site (whether BS 7909 style or otherwise) or being located in transportable assemblies, the very concept of "fixed wiring" has probably had its time. 

To my mind, I'm not sure that attempting to 'fudge' the requirements is the right approach.

I don't disagree in principle at all. I do find it interesting to try and disassemble the underlying logic sometimes though. Say we had a substantial bit of kit that we were fundamentally trying to hard wire to the installation, but it came with a "appliance connector" of some sort (probably more to make the 1st stage more easily replaceable during maintenance rather than for any portability reasons) - would we still want to regard it as a socket outlet?

   - Andy.

AJJewsbury said:

Certainly open to interpretation. In these times where some entire installations could consist of flexes plugged together on site (whether BS 7909 style or otherwise) or being located in transportable assemblies, the very concept of "fixed wiring" has probably had its time.

Also, construction sites, exhibitions, shows & stands (not covered by BS 7909), etc. ... there are other examples out there.

AJJewsbury said:

Certainly open to interpretation. In these times where some entire installations could consist of flexes plugged together on site (whether BS 7909 style or otherwise) or being located in transportable assemblies, the very concept of "fixed wiring" has probably had its time.

Also, construction sites, exhibitions, shows & stands (not covered by BS 7909), etc. ... there are other examples out there.