Using a 13 amp socket on a 5 amp circuit

[#1]

I have a simple small radio which has run off the lighting circuit (5 amp) for thirty years without issue, using an old, three round pin 5 amp socket.  The 13 amp ring main runs no-where near this radio, and therefore the lighting circuit is the only source of electricity.

Sadly, after years of loyal service, the radio has run out of gas - actually, the FM signal no longer works reliably.  If I move the radio elsewhere, it works o.k. but not where I want it, and where it has worked happily all these years.

So, I have had no alternative but to buy  a small internet radio working off the broadband WiFi which works perfectly.  The problem is that I have to use an extension cable from another room, because of course the power is supplied through the usual 5 volt DC transformer that anything electronic comes with these days, which of course requires a standard 13 amp socket !  

As a long term solution, I am therefore proposing to replace the old 5 amp round pin socket with a regular 13 amp socket.  "NO" I hear you all say .....  But I intend to take precautions by bridging the live 5 amp lighting circuit wire in the wall-socket box with a 3 amp inline fuse to the nominal 13 amp socket itself.  This should ensure that anyone trying to use the socket for anything other than the radio will blow the 3 amp fuse if they exceed 3 amps, thereby protecting the lighting circuit itself.  I will also stick a warning sign on the socket to read "5 AMP ONLY", and may even cover it.  (I presume actually that, without the inline fuse, an overload of the lighting circuit would just blow the lighting circuit fuse, but I do not want the house plunged into darkness if that were to happen for some extraordinary reason).

By doing this, I can then plug the 5 volt DC transformer into the nominal 13 amp socket without risk of someone else trying to draw more than 3 amps from it; if they did, it would just blow the 3 amp inline fuse without affecting the 5 amp lighting circuit - in theory !

I am quite sure that this breaks ALL the rules, but is there in practice any reason why I should not do this ?  The socket can in reality only be used for the radio, and it is highly unlikely that anyone would try to plug anything else into it for any reason as it is not very accessible.

Comments would be appreciated.  Thanks.

[#2]

Is this a wind up?

Have you not heard of the any of the regulations that apply?

Have a read here as a starting point

Could you also buy some of that yellow and black tape and surround the house to warn off any buyers in future, if it has not burned down by then.

[#3]

@WinfredVaughan 

Whether it meets the letter of the regs I have no idea but as long as the socket is fed from a fused spur labelled Max Fuse 5A then there will be no safety issue.

[#4]

but as long as the socket is fed from a fused spur labelled Max Fuse 5A then there will be no safety issue. 

In general I'd agree with that. The only proviso I'd add depends on how old the electrical installation is.

Some older lighting circuits were wired without CPC ( protective earth conductor ) , in which case its going to be a no-go.

[#5]

@Mustrum 

In my working life, many years ago, BS7671 sat on my desk as the equipment we produced needed to meet these regulations. For my sins I was responsible for the electrical safety of the bespoke equipment that we produced. Any-one who has had to read this weighty tome will tell you that it's about ensuring installations are safe. They don't tell you how to do it.

Then comes along 'experts' who produce guides. What these guides do is to produce instructions along the lines 'if you do it this way you will meet the regulations', regardless of alternative approaches to ensuring that the regulations can be met. This is fine but then this becomes elevated to being 'this is the only way to do it because that's what I have been taught'. Then along came building regulations which, whilst I have never studied them in full, I suspect are based on the same premise.

Just because wiring doesn't meet the strict regulations doesn't mean that it's dangerous or that your house will burn down.

Running a 13A socket off a 5A fused spur on a lighting circuit is cerainly undesirable and probably contrary to Part P of the building regulations. It is certainly undesirable but not dangerous. The risk comes in when some idiot changes the fuse to 13A, especially if the lighting circuit is wired in 1 sq mm cable. Hence the need for regulations to make electrical circuits idiot proof.

[#6]

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@Mustrum wrote:

Is this a wind up?

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I hope so. A 13A socket on a lighting circuit? 🙄

[#7]

@MisterW 

Some older lighting circuits were wired without CPC ( protective earth conductor ) , in which case its going to be a no-go.

I agree but rightly or wrongly assumed that this was replacing a 3 pin 5A round pin socket. I have installed one on a lighting circuit for a table light. I have had over recent years two NICIEC registered electricians see this and neither commented.

[#8]

Thanks for the sensible comments.  The wiring is all modern wiring, with 1mm twin and earth 5 amp cable, terminating with RCDs.

[#9]

@Baldrick1  the fact the OP came on a public Telecoms forum to ask the question should be the start of warning bells.

Whilst not yet as bad as the USA for regs, the ones we do have demand that any gas or electrical work is signed of by suitably qualified "professionals". I suspect a printed copy of this thread in the house paperwork may not be sufficient for a new buyer, nor from the insurance company should something go wrong. You can just imagine the conversation - "Oh but Baldrick and Mr W said it would be OK!"

Oh, and yes I do understand the theory behind what they are trying to do.

[#10]

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@WinfredVaughan 

Wouldn't it be a better idea to try and source another 5V power supply which had an inline mains lead, rather than the wall-wart type?

You could then replace the 13A plug with a 5A one, although obviously that type of plug wouldn't be fused.

EDIT:  Although having now checked, 5A fused plugs are available.

https://cpc.farnell.com/mk/641whi/5a-fused-round-pin-plug/dp/PL01928

[#11]

@WinfredVaughan 

If the RCD is properly rated then there should not be any danger of overloading the cable. I agree that a 3A fuse will give better coordination with a typical 6A rated lighting circuit MCB. 

[#12]

@Mustrum 

Fair enough. So you come to sell the house. A ‘professional’ electrician says that this socket is not acceptable. You agree and replace it with a 5A one. Where’s the problem?

By the way, I haven’t said that it’s OK per se. I have said that it is undesirable but can be done safely without it, as you have intimated,  resulting in dire consequences.

[#13]

I think I would be more concerned about the implications to my property insurance rather than if it is technically possible

Dan.

Sorry if I've spoilt everyone's fun

[#14]

In my younger days given the shortage of power sockets  it was not uncommon to use a  Y adaptor that plugged into the light socket. On one side would be a light bulb on the other side a plug to run a electrical device i.e. record player. 

[#15]

I just wish that one of the nay sayers would point to a regulation that explicitly forbids this arrangement where the cabling is protected with both a 3A in line fuse plus a 6A MCB in the consumer unit.