Spur off Double Socket.

[JohnW2]

I don't have it with me (I'm away), but I remember in the 14th Ed., something like you could have two single sockets or one double on an unfused spur.

Thanks. That's obviously what Harry and myself are both "vaguely recalling" !

Kind Regards,John

 

[ebee]

Can I just add, I think the spurs allowed only this, that and t`other and subsequent changes is a result of an attempt to keep things as simple rules of with few ifs and buts as possible aka KISS

 

[Mottie]

I've just had a thought. The double socket is either an end radial or potentially a spur off. (only L,N & E at rear of this socket), How can I tell if this is a spur off somewhere else or end radial? If it's a spur off somewhere else this would obviously mean my new single socket spur off might be off a spur which is a NO!

I know this is a no but from a 16A breaker in my CU, I have a 2.5 single feed to my garage at home. That goes to a double socket. From that socket there is a feed to another double socket also in the garage, a spur for the garage lights and security light and a feed to another double socket in the shed that runs a small freezer and a tumble drier as well as another spur for the shed lighting. Been like that for at least 10 years. Never had a problem.

 

[EFLImpudence]

Why do you think that is a no?

 

[ebee]

a 16A Breaker feeding any number of sockets in any configuration is (almost always) not a no and providing you have taken some regard to potential overloading by area served/liklihood of what might be plugged in and used at any one time then ok.
Upgrading to a 20A breaker just to add a bit more headroom might pretty much equally too.

 

[securespark]

What you have is a 16A (or, more usually 20A) radial circuit which can serve a floor area of not more than 50m². You can have as many sockets as you like.

This is different to an unfused spur taken off a ring final circuit.

 

[EFLImpudence]

... which can serve a floor area of not more than 50m².

Nonsense. Stop perpetuating these silly myths.

 

[Mottie]

Why do you think that is a no?

I’m sure I’ve mentioned it on here before and been told it was a no no. Is it okay?

 

[Harry Bloomfield]

I know this is a no but from a 16A breaker in my CU, I have a 2.5 single feed to my garage at home. That goes to a double socket. From that socket there is a feed to another double socket also in the garage, a spur for the garage lights and security light and a feed to another double socket in the shed that runs a small freezer and a tumble drier as well as another spur for the shed lighting. Been like that for at least 10 years. Never had a problem.

Basically, nowt much wrong with that, always providing it is covered by an RCD. You could even up the 16A, to 20amp, to allow a bit more 'headroom'.

My own garage/workshop/hut/summerhouse/garden feed, is a single 2.5mm. Installed 50 years ago, as a temporary supply, just to get power out to the garage for lights and a socket, it was fed from the downstairs ring, via an 13amp FCU. As time went on, it fed a huts socket and light, summerhouse, and outdoor sockets. I improved that, with a 10w consumer unit in the garage, but still all fed from that temporary 2.5mm, and the FCU - because the house consumer unit was desperately short of ways.

Only this year, did I finally get around to swapping the house CU, to one with more ways, and so was able to give the outdoor CU, it's own MCB, and do away with the 13amp FCU. I used a 20amp MCB.

In all the years, that FCU has been in use, I have never blown the 13amp fuse. I've often tripped the garage CU's MCB, working on various projects in the garage and workshop.

 

[Harry Bloomfield]

I’m sure I’ve mentioned it on here before and been told it was a no no. Is it okay?

Yes, it's fine. Just swap the 16amp, to a 20amp MCB - if and when you get a roundtuit.

Rather more urgent - Is that circuit covered by an RCD, or an RCBO?

 

[JohnW2]

What you have is a 16A (or, more usually 20A) radial circuit which can serve a floor area of not more than 50m²....

Another incidence of 'guidance' being cited as if it were regulations.

I don't know about 'ancient history (you're the expert on that!!)', but there has certainly not been ny such regulation in the last few editions of BS7671.

 

[Harry Bloomfield]

Another incidence of 'guidance' being cited as if it were regulations.

I don't know about 'ancient history (you're the expert on that!!)', but there has certainly not been ny such regulation in the last few editions of BS7671.

Sometimes, you have to just engage common sense, with regard to an installation, or a circuit - in normal use, is the circuit liable to overload, or tripping the MCB. Mottie hasn't reported even the 16amp as tripping, so the proof of the pudding....

 

[JohnW2]

Sometimes, you have to just engage common sense, with regard to an installation, or a circuit - in normal use, is the circuit liable to overload, or tripping the MCB. Mottie hasn't reported even the 16amp as tripping, so the proof of the pudding....

Quite so - and there is little common sense in a 'guideline' such as the one secure mentioned.

Depending upon the nature and use of a room, it might be 'quite likely' that a 16A circuit with just a few sockets in a tiny room would sometimes be 'overloaded', whilst, in different circumstances, such overload would be 'very unlikely' in a massive room with countless sockets.

 

[ebee]

What you have is a 16A (or, more usually 20A) radial circuit which can serve a floor area of not more than 50m²

I think that strictly speaking that is guidance - it is a good idea to follow guidance in most circumstances because it is usually put there for good reason, if you choose not to follow it then by using sound engineering judgement then I would be ok with that, but if you have not got the combination the competence by virtue of qualifications and experience then it is more sensible to follow the guidance. Guidance is there for a reason and whilst it does not cover every case it is often basically a set of simplified rules it is expected in most cases to achieve the objective goal of trouble free and safe installations.
I myself would be foolhardy not to follow guidance on cars and plumbing and a load of other things.
I would probably be deemed ok to not always follow some guidance on certain aspects of electrical practice yet I would still ensure that I always follow BS 7671 (Wiring Regs).

Strictly speaking BS 7671 is, in itself, guidance not law, however we treat it as if it is actually the law though.
If by contract, including if you are registered with one of the competent schemes then you must follow it by law,
Plus, if by coming under Landlord Legislation, then one certain version of BS7671 must be followed by law anyway in certain circumstances.


Effectively parliament decides which version of the regs must be followed as law but that does not give carte blanch for successive updates of BS 7671 to become a legal requirement of parliament, they might authorise a government minister or government office do do that on parliaments behalf.

 

[JohnW2]

I think that strictly speaking that is guidance - it is a good idea to follow guidance in most circumstances because it is usually put there for good reason,

The problem is that unless the guidance is so 'conservative' ('ultra-cautious') as to be almost 'fool/idiot-proof) (which will often make it 'unrealistic'), it really relies upon those who may apply it to have the skill and knowledge to know when it is appropriate guidance (in which casethey probably would not need the 'guidance', anyway!)_

As I've said, the 'guidance' that "a 16A radial can serve a room/area of up to 50 m²" is all very well, but anyone applying that guidance really needs to understand that a 16A circuit might be pitifully inadequate in some rooms/areas a lot smaller than 50 m².

Kind Regards, John