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What does BS7671 mean by an "installation coupler" 411.3.3 Note 5?

JHFE

What does BS7671 mean by an "installation coupler"  411.3.3 Note 5?

Is this a proprietary connector or standard connector used in a singular and specific way purely for a particular installation application?

I will be providing a new circuit in a domestic setting which supplies power to a yet-to-be-installed garden office pod.

 

The Pod supplier/builder has specified a 32amp 230v BS EN 60309-2 Commando socket at the end of the circuit.  They then deliver and build their pod and connect a flexible lead from the back of the pod to the socket/circuit I provide.  This in turn powers a 40A 30ma 2-way consumer unit, pre-wired at the pod building factory. In other words, outlets and lighting in the pod are RCD protected.

 

My circuit will come from CU (DB2) which I will fit and SWA will run from DB2 all the way to the outlet near the garden pod. (15-18 metres on 6mm2 SWA)

 

My question relates to RCD requirements.

 

In the interests of Selectivity, I could run the SWA from just an MCB, as the SWA negates RCD protection for the cable itself.  However, if the 32amp commando I fit is classed as a "socket outlet", I could be failing to provide RCD protection where BS7671 requires it.

 

411.3.3 Note 5 pg65 A2:2022 - states that an "installation coupler" "is not regarded as a socket outlet for the purposes of this regulation"

 

Would it be fair to class this connection between pod and circuit as an installation coupler?  It is unlikely to be accessed by lay persons to, let's say, power a lawn mower and will be behind the pod and not readily accessible to lay persons, once the pod is installed.  It will more than likely be connected once and stay permanently connected for many many years without interference.

 

Or

 

The 32amp outlet used to connect the pod to power is without question a socket outlet and therefore 411.3.3 must be obeyed and the cable run from DB2 to the outlet must be RCD protected?  Even if I sacrifice selectivity as the lesser of 2 evils and have 30ma upstream and downstream?  (or fit time delay upstream)

 

Any advice is much appreciated. Thumbsup tone1

 

Cheers

James

 

Other info.  single phase, domestic setting, TNCS, 8-year-old property, "17th edition" dual RCD (AC wave) split board for the main house, no existing SPD.

  • 0

    Not being protected against UV degradation would limit the use of SY cable outdoors, in amongst all the other issues.

    This is not a difficult installation, the SWA just needs making off into the pod consumer unit and the plug, socket, SY cable and stuffing gland returned to sender.

  • 0

    If the intention is to claim compliance with Section 717 Mobile or transportable units, compliance with 717.411.4 is required, so the socket earthing arrangement cannot be TN-C-S PME, unless the pod is craned up onto the roof of the house so it is sat on top of the electrical installation that supplies it.

    The pod manufacturers trying to make life easy for themselves makes things a lot more complicated for everyone else, as well as more expensive for the customer.

  • 0 in reply to gkenyon

    One could potentially include it in 717 that Graham it is true, but then the definition between appliance and fixed is blurred even further. However if you try to make it a "caravan" the connecting cable etc. is defined and that is not what is supplied with these pods! Clearly then they are not intended by the manufacturer to be covered by 717, and he sees that the best definition is as an appliance connected with a plug and socket. As they are wooden, a lot of 717 is irrelevant, and a normal 30mA RCD supply would seem to me to be entirely safe. Feature creep is a terrible thing!

  • 0

    But following your own logic, it is a fixed building and therefore it can! Now explain why you think there is a difference, there are probably no services or extraneous conductive parts, although these are easily dealt with if present. Your problem seems to me in deciding what is "inside" and what is "outside", and perhaps you should consider an electric vehicle and a 13A plug lead. These must be contra BS7671, but widely available and used. SY provides a useful degree of extra mechanical protection, and its UV ability affects many air-con installations without any problem, because the sheath (outside the wire) is only rust and scrape protection. Failed pieces are very unusual.

  • 0 in reply to David Stone

    Agree. If the makers decide that bits of the UK national wiring regs do not apply, but their own rules do, then that is a matter for them and their legal team. Showing that it is equivalently safe to either should do.

    If an installer follows the maker's advice and plugs the building in, he has some defence, in that  the maker's inductions said it was what should be done.

    Not to do so is equally well defended by ' the voice of BS7671 told me to do it' .

    Which is the best course is a judgement call when you rock up on site and look at it - is being able to unplug it going to be useful or not - when they go on holiday perhaps ? 
    I might do either and I might put the socket in some sort of box or cupboard , given it is un-shuttered and un-interlocked and it sounds like more of  a domestic situation than the usual portakabin at a pop festival.

    Mike.

  • 0 in reply to David Stone
    David Stone said:
    and its UV ability affects many air-con installations without any problem

    But if the manufacturer specifically states in their product information 'These cables are not used for outdoor or underground installation.' then they are not suitable for that purpose?

  • 0 in reply to gkenyon

    Problem is a lack of agreement 'SY' on its own is a bit of a broad category-  some say  it is OK, some are a bit on the fence- this make of SY is OK for 'protected outdoors'  for example- so presumably not exposed to storms on a seafront but perhaps clipped to the eaves of a building or the side facing the fence, and the parts of a fairground ride less open to the elements. The lack of agreement is the issue here. Better perhaps to specify the maker, or at least the required UV and general weather resistance.


    In sunnier climes you will find a similar cable to CY but with dark UV blocking outer jacket in place of a clear one, and a silver coloured  braid that is actually a tinned copper rather than steels. . cy-jz-0.6-1kv

    Mike.

  • 0

    Whilst we are at it I would much prefer to see the consumer unit installed inside the pod.

    It is amazing how many hours of discussions there are on Internet forums about how to wire a wooden garden shed.

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