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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.

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    Presumably they don't have electricians in their installation crews, so prefer a 'plug and play' solution. We do the same in IT centres - racks that won't likely move in decades are still connected using 60309 connectors, simply to allow IT staff to re-configure things as they wish without the risks inherent in getting a screwdriver out and messing with exposed ends of individual wires.

    Some modular building systems also use connectors between units - so they can be simply plugged together on site.

    I'd also have concerns about using an unshuttered socket in a domestic environment (you might want to draw the supplier's attention to BS 7671's requirement for shuttered sockets in domestic environments) - if you need something over 13A then a interlocked 60309 socket would be my preference (so the socket can only be switched on after a plug is inserted and must be switched off before the plug can be withdrawn). Ideally the switch should be rated for isolation, but even the conventional 'functional only' switches would be a significant improvement over continuously live socket contacts.

    If the pod has a single 30mA RCD as an incomer device, then there is no selectivity issue at all in having another 30mA RCD upstream that only covers that socket - whichever (or both) RCDs trip, exactly the same set of appliances and sockets are disconnected - there is no selection to be had. It's the same situation with caravans - where both the site sockets and caravan incomer have their own 30mA RCDs.

       - Andy.

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  • 0

    Presumably they don't have electricians in their installation crews, so prefer a 'plug and play' solution. We do the same in IT centres - racks that won't likely move in decades are still connected using 60309 connectors, simply to allow IT staff to re-configure things as they wish without the risks inherent in getting a screwdriver out and messing with exposed ends of individual wires.

    Some modular building systems also use connectors between units - so they can be simply plugged together on site.

    I'd also have concerns about using an unshuttered socket in a domestic environment (you might want to draw the supplier's attention to BS 7671's requirement for shuttered sockets in domestic environments) - if you need something over 13A then a interlocked 60309 socket would be my preference (so the socket can only be switched on after a plug is inserted and must be switched off before the plug can be withdrawn). Ideally the switch should be rated for isolation, but even the conventional 'functional only' switches would be a significant improvement over continuously live socket contacts.

    If the pod has a single 30mA RCD as an incomer device, then there is no selectivity issue at all in having another 30mA RCD upstream that only covers that socket - whichever (or both) RCDs trip, exactly the same set of appliances and sockets are disconnected - there is no selection to be had. It's the same situation with caravans - where both the site sockets and caravan incomer have their own 30mA RCDs.

       - Andy.

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