Summerhouse/Outbuilding wiring thoughts?

[Dan Buc]

So, my dad is finally getting a summerhouse built in his garden, and looks like Ill be doing the wiring. Now its not one of those flat pack assembly kits things; its the real deal joiners, builders, etc. Before we go any further, I know this work is notifiable and he intends on getting his sparky mate to check it and sign it off.

So, he said he only wants one 2 gang socket (for tv and beer fridge) and 4 Led downlights? peasy ( I think), but breaking into the main consumer unit in the house from a new mcb aint an option as it would mean ripping up 5 floors to get to it.

So heres my plan:

There is a new extension(utility room) around 4m from the summerhouse that's ring runs from its own mcb in CU. On the ring there is a 1 gang socket powering a fridge freezer and a 2 gang socket that has never been used inside a cupboard that is on the main wall.

So, I'm going to remove the double socket, replace with a 13a RCD fused spur, travel out brick wall directly from here into an ip65 junction box using 2.5mm T+E. From Junction box, run 2.5mm SWA cable along garden wall to a 'garage' type mini consumer unit on the exterior wall of the summerhouse. From the CU, use 1.5mm T+E to feed 4 led downlights from 3a MCB and use 2.5mm T+E to feed a 2 gang socket from a 13A MCB(replacing the standard 16A) .

I was going to use an RCD spur in the house simply for protection from the cable run outdoor.



Thoughts?? ))

 

[magico]

If you don't wanna rip up the floors. Armoured cable all the way round the outside of the house wall. Clipped and to fuse box entry. Or let your dads sparky mate do it all. And he'll want more than 1 double socket for sure

 

[Taylortwocities]

There is a new extension(utility room) around 4m from the summerhouse that's ring runs from its own mcb in CU.

Is this circuit protected by an RCD? If so, you do not need an

13a RCD fused spur,

just a fused spur with a 13A fuse in it.
In the outhouse, terminate the SWA directly to a double socket.
From the double socket cable to a switched fused spur with a 3A fuse in it
( this will be the light switch). Connect your lights to the load side of this FCU.

That’s it. You do not need a garage cu in the outhouse. It’s pointless.

 

[yorkspark]

Also bare in mind, you cannot install a bs7288 rcd spur onto a non rcd/rcbo protected circuit anyway, so will defeat the purpose of buying one.

 

[winston1]

You don't need 1.5mm for 4 LEDs or any lighting circuit. 1.0mm is standard.

But anyway if your dads sparky friend is going to "sign it off" he will have to design it and supervise the work. That is what he is signing to say he has done. Is he a scheme member?

 

[333rocky333]

Also bare in mind, you cannot install a bs7288 rcd spur onto a non rcd/rcbo protected circuit anyway, so will defeat the purpose of buying one.

Can you elaborate on that please, I take it your referring to 531.3.4.1 not mentioning RCD spurs or sockets,
However surely, 411.3.3 requirements are covered by a 30ma Rcd spur or socket regardless of its Bs number

 

[yorkspark]

From January 2019, BS 7288 is NOT listed in BS 7671:2018 Appendix 1

This is down to their product standard not stating they are suitable for additional protection, and requiring an upstream 30mA RCD to provide this function, if a device to BS 7288 does not provide additional protection then it offers no benefit over and above a normal socket/spur outlet which is MUCH cheaper.

Plus they require an upstream RCD to provide the additional protection, thus there is no selectivity.

Therefore they are a device without a valid use under BS 7671, this is why they have been omitted form the listing of RCD types, and uses, and why the standard has been omitted from Appendix 1.

 

[plugwash]

There was a thread on the IET forums (can't find it now sorry) which IIRC came to the conclusion that the writers of BS 7288:2016 essentially ****ed up and wrote a standard for a useless product. It seems unclear if and when the appropriate standards comittes will be able to resolve this and give us a standard for RCD sockets and FCUs that is actually useful.

Perhaps it was https://communities.theiet.org/discussions/viewtopic/1037/24702 but that thread doesn't seem to be what i'm remembering, maybe it was a different one.

 

[SUNRAY]

There was a thread on the IET forums (can't find it now sorry) which IIRC came to the conclusion that the writers of BS 7288:2016 essentially ****ed up and wrote a standard for a useless product. It seems unclear if and when the appropriate standards comittes will be able to resolve this and give us a standard for RCD sockets and FCUs that is actually useful.

Perhaps it was https://communities.theiet.org/discussions/viewtopic/1037/24702 but that thread doesn't seem to be what i'm remembering, maybe it was a different one.

I don't quite get the problem here, I helped with correcting some problems on a workshop inspection last year. 32A radial in surface mounted conduit for 3 IR wall mounted heaters. A SFRCD had been installed for a 13A DSSO. The heating circuit itself didn't require RCD, I don't see why the SFRCD was unsuitable. Luckyly there was plenty of space in the tube to add a new radial.

 

[flameport]

the writers of BS 7288:2016 essentially ****ed up and wrote a standard for a useless product

That's basically it - the standard now states that upstream RCD protection is required when using an RCD socket outlet, and that such things are only useful for 'supplementary protection' with the additional protection being provided by an RCD for the circuit.
There is more about them not being suitable for isolation purposes either.

RCD options for additional protection are those to BSEN 61008 or BSEN 61009, neither of which includes socket outlets or FCUs.

 

[EFLImpudence]

 

[Taylortwocities]

Yes, but it is additional to basic protection. And RCD isn’t basic protection.

or did I miss something?

 

[flameport]

For BS7288, it's implied that:
Fault protection - fuse or circuit breaker
Additional protection - from a 30mA RCD to 61008 or 61009 (as in section 415 in BS7671)
Supplementary protection - the undefined purpose that a socket outlet RCD provides.

Dictionary definitions of words and what they mean in certain standards are generally unrelated.
The meaning of words in one standard are often completely different to the same words in another standard.
One standard directly conflicting with another is a regular event.
Colossal mistakes and obvious blunders are commonplace.

Given the mess that was added in BS7288:2016 which made the whole point of the devices entirely irrelevant, those who amend BS7671 had no other choice but to remove any reference to it.

BS means British Shambles.
BS EN is the British Shambles version of European Nonsense.
It's not supposed to make sense.

 

[EFLImpudence]

Is it allowed to have an additional supplementary SRCD?

 

[JohnW2]

That's basically it - the standard now states that upstream RCD protection is required when using an RCD socket outlet, and that such things are only useful for 'supplementary protection' with the additional protection being provided by an RCD for the circuit. ... There is more about them not being suitable for isolation purposes either.

We've discussed this before and I still don't really see the purpose for having a Standard for an item of equipment (or, indeed, the item of equipment itself) which essentially appears to have no useful purpose.

It's also a bit worrying. Goodness knows what 'supplementary protection' means, but even if it merely means 'redundancy' ('belt and braces'), if I felt the need for such 'extra protection', I don't think I would be very comfortable with a device which, for whatever reason, the Standard said could not be relied upon to give 'additional' protection.

'Additional protection' surely only requires a device which will operate in response to a residual current ≥30mA. If an SRCD cannot be relied upon to do that, then what (if anything) can it be relied upon to do?

Kind Regards, John