Installing new 13A socket next to existing socket

[SUNRAY]

... It would not, for example, be a good idea to run it like a radial then at the far end bring a long leg back to the origin, that would be a not so well designed ring approach. And yes I think with the OPs question the actual loading would probably be not much.

Silly or not, I've found it a few times, one that instantly springs to mind was a series of offices built in a wharehouse against one wall which had a trunking running just above the new ceiling level. All modular partition style so each office was about 4m wide, 2 condiut/double sockets drops fitted in each office. I can't remember the exact numbers but drops were say 2m x 4 so roughly 12m (plus the return making 16m) of wire per office and feed DB some distance from one end, something like 30-40m adding 60-80m.
So ring from DB to closest office, looped along the row to furthest end then return the whole length back to DB. The circuit was well over the 106m permitted.

 

[ebee]

Rings have their purposes and can have advantages if wired correctly.
Indeed Sunray, I have found a few like you mention. If someone wants to wire as a ring using one length of trunking then it makes sense to wire every intermittent one on the outgoing leg and then every intermittent one on the other leg. More spread and balance (if all other things are equal).

Although the question might then be , would a radial suffice as a better option anyway?

 

[JohnW2]

No John it is not usually a problem. More theoretical. But if you endeavour to make a first approximation using the middle third and/or spread about evenly so to speak you are unlikely to wander that far off the mark both regard possible loading and actual real life too that it is getting anywhere near a likelihood. I did say more of a back of a fag packet approach (I doubt anyone goes to great lengths planning/measuring or unduly worrying about it).

As I've been saying, I totally agree, the only small difference between us is that my "fag packet" is inclined to say that two-thirds is adequate. As for ...

.... and/or spread about evenly so to speak ...

That's really no different - since if the load is 'spread evenly' then 'most of it' will inevitably be in the 'middle two-thirds' (and a third of it within the 'middle one-third'). Mind you, within that 'middle two-thirds', it doesn't matter whether or not the loads are evenly spread, at least in terms of possible 'overloading' of cables - there would be no risk of overloading if all of the load in the segment were at one end of the segment.

However I think many of us would try to avoid an "all at one end" scenario

That's probably true, but not really necessary provided that the 'rules of thumb' we've been discussing are adhered to.

Kind Regards, John

 

[JohnW2]

Silly or not, I've found it a few times ...

I suspect that most of us have seen it (and may even have 'done it' at times!). It could be said to be a little 'silly', but nothing wrong with it if it is actually 'compliant' - the alternative being to forget the 'return run' and wire it just as a radial, using fatter cable.

The circuit was well over the 106m permitted.

There is no 'permitted limit', per se. That 106m figure results from consideration of VD recommendations, assuming 20A at the centre of the ring and a further 12A evenly distributed across the rest of the ring. However, assuming it's 2.5mm² cable,then "well over 106m" could well result in failure to satisfy the Zs requirements.

Kind Regards, John

 

[Sparky54]

Thanks for all the comments and thoughts. The ‘new technology’ for us is very low current, FTTP box, router and an Alexa thingy. There are two other double sockets in the bedroom, one unused by the door, which will be used for higher-current devices. But, as you say, new owners may have different plans… I think a fused triple socket instead of another double will be the answer, didn’t know they existed (I did 35 years on low-voltage, AF and RF wiring, not mains wiring). A flush-mounted version with a triple back box looks ideal. The 4th socket was a spare which I can live without. Thanks again.

 

[robinbanks]

If they all run on 12v can you use your LV skills to:

* cut all the wires off the adapters for these products
* solder them onto one decent, higher amps output 12v adapter

Thus running three 12v appliances from one adapter?

Did the same thing in my comms cabinet, where the lighting controller, two Ethernet switches, router and thermostat hub were all the same voltage; one 3A adapter runs them all

The PoE injectors couldn't have the same trick applied, but I saved a plug for those by wiring their two kettle leads into the same plug

 

[RandomGrinch]

but I saved a plug for those by wiring their two kettle leads into the same plug

"Y" leads are readily available, although they are an 'intersting' item to PAT and label!

https://cpc.farnell.com/pro-elec/pe01092/lead-uk-plug-to-2x-iec-c13-skt/dp/PL13331

 

[JohnW2]

If they all run on 12v can you use your LV skills to: ...

Some joker is bound to point it out to you - so, to get in first ..

... whilst we all 'know what you mean' (although some believe that 'not to be the point'!) anything up to 1000 V AC (or 1,500 V DC) is, per industry (IEC) terminology, "LV"

Other than that, I agree with you, and have done similarly myself at times.

Kind Regards, John

 

[ebee]

Yep, LV = utilisation voltages and HV is distribution/transmittion voltages in a nutshell.

LV can be further broken down into RLV, ELV which includes SELV, PELV and FELV.

You can make a song about it to the tune of "three blind mice" if you like.

 

[Arzon]

Ah! Didn’t know there were so many LV sub-sets. Low voltage for me was usually 12, 24 and occasionally 50V DC and RF power from the transmitters was up to 250W. Every day is a school day!
Also… Seem to have logged in from another account my phone had stored.

Sparky54

 

[JohnW2]

Ah! Didn’t know there were so many LV sub-sets. Low voltage for me was usually 12, 24 and occasionally 50V DC ...

It still IS for the vast majority of the general public, who therefore consider "Low Voltage" essential as "safe to touch" or even "safe for children to play with". It is a tiny proportion of the population (those in the 'electrical industries') who have turned that into a potentially dangerous misconception !

Kind Regards, John

 

[plugwash]

In english low and high are terms whose meaning depends on context. What is high in one context may be low in another.

Unfortunately the standards body have taken a power distribution networks idea of high and low and pushed them into the domestic/commercial electrical installation world,

 

[JohnW2]

In english low and high are terms whose meaning depends on context. What is high in one context may be low in another.

Indeed so.

Unfortunately the standards body have taken a power distribution networks idea of high and low and pushed them into the domestic/commercial electrical installation world,

Exactly. Most of the 'general public' (i.e. the vast majority of the population) have a notion of the meaning of "high voltage" and "low voltage" in the context of their own lives and environments and, as you say, it seems more than a little unfortunate that the 'standards body' has tried to push definitions appropriate only for distribution networks onto that general public.

If there is a ';saving grace', it's that their efforts have largely failed. In forums like this, the pedantic amongst us might try to 'correct' members of the public but I don't think that has any significant effect on the great majority of that public - who continue to regard 230V as "high voltage" (and therefore 'dangerous').

Kind Regards, John

 

[ebee]

I think at the outset we should point out the parameters. Whilst we refer to High and Low in the industry approved sense we should make it clear that we also recognise what a vast majority of people think those terms actually mean. For clarity we often need to make such a comment.
Terms such as Live, Line, Earth, Ground are easy examples . Electrocution V Electric Shock. Ring Final/Ring Main. Spur is a good example, many people (including electricians) say Spur when the mean a fused connection unit (usually a switched one). The list of such things is quite big. The same happens in the everyday world too. Quite often there is a general meaning of a word/phrase and also a technical meaning and also a legal meaning. So three or more slightly different meanings to a lot of things. Whether to clarify at the outset or just stick to the technical meaning on , for example, this forum.

 

[JohnW2]

I think at the outset we should point out the parameters. Whilst we refer to High and Low in the industry approved sense we should make it clear that we also recognise what a vast majority of people think those terms actually mean. For clarity we often need to make such a comment.

I agree totally, and have very often said that - but my personal view is that we should merely inform people about the 'industry terminology', not 'correct' them or try to persuade them to use that 'industry technology'.

Terms such as Live, Line, Earth, Ground are easy examples . Electrocution V Electric Shock. Ring Final/Ring Main. Spur is a good example, many people (including electricians) say Spur when the mean a fused connection unit (usually a switched one). The list of such things is quite big.

Quite so. And my view about such things is exactly the same as above. If there is actually true ambiguity, one obviously has to ask for clarification (as well as 'informing'), but that is rare (i.e. we nearly always "know what was meant"). It's worth remembering that people who work in any 'specialised field' (e it 'electrics' or anything else) are also 'members of the general public', so really can't claim that they don't understyand the terminology used by the general public.

The same happens in the everyday world too. Quite often there is a general meaning of a word/phrase and also a technical meaning and also a legal meaning. So three or more slightly different meanings to a lot of things. Whether to clarify at the outset or just stick to the technical meaning on , for example, this forum.

Very much so. One of the most dramatic examples is seen in Medicine - and, in that context, even the 'informing' is not generally practical. Doctors, nurses and other healthcare professionals simply have to 'accept' (usually without any comment) 'lay terminology'. I can tell you that if they always attempted to educate patients about the 'correct medical terminology', they would probably spend more time doing that than they spent actually providing healthcare!

Kind Regards, John