topic Re: Using a 13 amp socket on a 5 amp circuit in Tech Help - Software/Hardware etc

Using a 13 amp socket on a 5 amp circuit

WinfredVaughan — Wed, 22 Sep 2021 13:07:41 GMT

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.

Re: Using a 13 amp socket on a 5 amp circuit

Mustrum — Wed, 22 Sep 2021 13:15:52 GMT

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.

Re: Using a 13 amp socket on a 5 amp circuit

Baldrick1 — Wed, 22 Sep 2021 13:20:04 GMT

@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.

Re: Using a 13 amp socket on a 5 amp circuit

MisterW — Wed, 22 Sep 2021 13:43:06 GMT

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.

Re: Using a 13 amp socket on a 5 amp circuit

Baldrick1 — Wed, 22 Sep 2021 13:48:51 GMT

@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.

Re: Using a 13 amp socket on a 5 amp circuit

198kHz — Wed, 22 Sep 2021 13:50:11 GMT

@Mustrum wrote:

Is this a wind up?

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

Re: Using a 13 amp socket on a 5 amp circuit

Baldrick1 — Wed, 22 Sep 2021 13:54:52 GMT

@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.

Re: Using a 13 amp socket on a 5 amp circuit

WinfredVaughan — Wed, 22 Sep 2021 13:56:58 GMT

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

Re: Using a 13 amp socket on a 5 amp circuit

Mustrum — Wed, 22 Sep 2021 14:07:55 GMT

@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.

Re: Using a 13 amp socket on a 5 amp circuit

RobPN — Wed, 22 Sep 2021 14:18:27 GMT

@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

Re: Using a 13 amp socket on a 5 amp circuit

Baldrick1 — Wed, 22 Sep 2021 14:15:53 GMT

@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.

Re: Using a 13 amp socket on a 5 amp circuit

Baldrick1 — Wed, 22 Sep 2021 14:25:45 GMT

@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.

Re: Using a 13 amp socket on a 5 amp circuit

Dan_the_Van — Wed, 22 Sep 2021 17:02:06 GMT

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

Re: Using a 13 amp socket on a 5 amp circuit

Champnet — Wed, 22 Sep 2021 19:15:10 GMT

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.

Re: Using a 13 amp socket on a 5 amp circuit

Baldrick1 — Wed, 22 Sep 2021 20:55:04 GMT

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.

Re: Using a 13 amp socket on a 5 amp circuit

MJN — Wed, 22 Sep 2021 21:44:01 GMT

@Mustrum wrote:
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".

Can you be more specific? If you're referring to the notification requirement of Part P then that only applies to new circuits, replacement consumer units and any electrical work in a 'special' location (a room containing a bath/shower, swimming pool or sauna heater). There is no need to have the addition of a socket to an existing circuit 'signed off', but it is required to be compliant to the regs.

With regards to the regs, and BS7671 in particular, there is no black-and-white rule either way regarding adding a 13A socket to a lighting circuit. It does go near the subject though, for example it says that a 'lighting' circuit can have a BS1363-compliant socket (which a reputable 13A socket would be) attached to it although elsewhere it states that a 'power' circuit must use a minimum conductor size of 1.5mm²and so if plugging a non-light into a lighting circuit does that therefore make it a power circuit in which case the commonplace 1.0mm² 'lighting' wiring might therefore be deemed inadequate? The regs remain silent on that point.

As always the regs are often open to a certain amount of interpretation - intentionally - because often there is no one size fits all rule. Hence, deviation from the regs is not automatically deemed a contravention. There is room for pragmatic judgement, and in the case of 13A sockets on lighting circuits this is frequently exercised - there are thousands of houses across the country with TV distribution and masthead amplifiers plugged into 13A sockets on lighting circuits because often that is the only power source available in lofts. Likewise with undercupboard lighting using plug-in lighting but where wall switch control is still desired. Professional electricians will usually mark up the socket to advise against plugging anything else in and some (along with perfectionist amateur DIYers, usually) will also add in an 3A FCU for belt and braces protection against such a situation occurring and in doing so helps uphold the regulatory requirement to minimise the risk of long-term small-overload (i.e. non fault) situations occuring.

An alternative, albeit bulky, approach would be to stick with the round pin 5A socket and make up a 5A plug to 13A socket adapter lead through which to power the new radio. This requires no modification to the fixed wiring whatsoever, although the risk of plugging something else in would persist for as long as the adapter lead remains in existence.

Personally, I'd go with a 3A FCU and marked-up 13A socket. I'd possibly ditch the 3A FCU if there were practical or significant aesthetic issues and not lose any sleep whatsoever.

Re: Using a 13 amp socket on a 5 amp circuit

WinfredVaughan — Wed, 22 Sep 2021 22:38:34 GMT

Thanks for all the contributions and sorry it has "sparked" such indignation !

I prefer to go with common sense. Life's too short for Pythonesque heel-clicking. My old radio has been plugged into the lighting circuit for thirty years and it will continue to be but with a 13 amp socket and 3 amp inline fuse. I can easily secure the transformer to ensure it cannot be removed.

If I were to buy an inline transformer, I would run the risk of invalidating the guarantee on the radio, although I am grateful for the suggestion.

A 13 amp fuse in the plug, tamper-proofing the transformer, a 3 amp inline fuse in the wall box and an RCD terminating the lighting circuit is enough belt and braces for me, especially as there are only two of us in the house and no-one is even likely to know that the socket is there, so little risk of anyone tampering with it.

I live in the real World, and believe it is always best not to be too proud to ask, but to seek information and then to weigh up the answers on the back of knowledge and practicality. The trouble with feigned indignation is that it discourages people from seeking advice in the first place ! Some of you may care to bear that in mind in future.

Once again, I am most grateful for the sensible input.

Re: Using a 13 amp socket on a 5 amp circuit

Baldrick1 — Thu, 23 Sep 2021 07:15:17 GMT

@MJN wrote:

With regards to the regs, and BS7671 in particular, there is no black-and-white rule either way regarding adding a 13A socket to a lighting circuit. It does go near the subject though, for example it says that a 'lighting' circuit can have a BS1363-compliant socket (which a reputable 13A socket would be) attached to it although elsewhere it states that a 'power' circuit must use a minimum conductor size of 1.5mm²and so if plugging a non-light into a lighting circuit does that therefore make it a power circuit in which case the commonplace 1.0mm² 'lighting' wiring might therefore be deemed inadequate? The regs remain silent on that point.

Personally, I'd go with a 3A FCU and marked-up 13A socket. I'd possibly ditch the 3A FCU if there were practical or significant aesthetic issues and not lose any sleep whatsoever

Thank you for an opinion based on facts.

Re: Using a 13 amp socket on a 5 amp circuit

WinfredVaughan — Fri, 24 Sep 2021 05:40:30 GMT

As a closing comment, following MJN's sensible suggestion, I have decided to keep the original 5 amp socket to which I will plug in a short extension lead, at the end of which will be a 13 amp socket and enclosure with an inline 3 amp fuse, into which the transformer will be plugged; the power cable will then exit the void and run back up the cupboard to the new radio.

I have discovered that the floor cupboard fixed to the wall in question (a standard kitchen cupboard, but to avoid Mustrum raising another hare, I hasten to add this is NOT in a kitchen of any sort) of course has the usual kickboard hiding the adjustable plastic feet. By removing the kickboard, I will hide the transformer in the void underneath out of sight, strapped firmly to the 13 amp socket to prevent the socket from being used for anything else, and then simply replace the kickboard.

This solution ticks all the boxes.

So thanks to everyone for an entertaining but nevertheless instructive discussion. It has been most helpful.

Moderators Note: Needlessly insulting paragraph removed.

Re: Using a 13 amp socket on a 5 amp circuit

VileReynard — Tue, 28 Sep 2021 18:22:43 GMT

It still doesn't stop anyone unplugging your radio and running an electric fire on the lighting circuit.

Do it properly and use a 13A circuit!

Your lighting socket should have a blanking plate installed.