Why does the UK use rings for sockets?

[pc1966]

I'v obviously lead a sheltered life, especially over the last four weeks, cost seem a bit prohibitive, but then if you take into account the three modules it replaces, perhaps not that expensive, thanks for that.

With AFDD you are looking at something in the £1-2k region for a full CU at trade price, so it is something that is a very difficult to sell to most folk.

It is also a little unclear as to how effective they are in real terms, and so far no test equipment that I know of so for the 'AFDD' aspect you are trusting the self-test, though obviously you can verify the RCD action which provides some confidence on the electronics and mechanical trip reaction.

I suspect they will come down in price though but no idea how long for that to show.
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I have come to the conclusion that you can't get true separation of 3mm on each pole without the extra width, which seems logical when you consider the doubling up of the number of mechanical components needed, obviously flying leads are not required.

I can't see a problem in getting 3mm clearance when open, but I can see a problem in having an arc-quench chamber in a single-module size device if you were interrupting a N-E fault at high current.

Do you have a specific reason for needing this?

 

[Mike Johnson]

I think you'r right, the problem is IMO, domestic electrical instals are to a greater extent very reliable, so it's not seen as a priority to improve what is already working well, the old adage "If it ain't broke......." seems to be the majorities mantra.
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@pc1966 the only reason for needing this is the French regulations which stipulate dual pole 3mm gap, they are a bit behind in not using RCBO's in the main, but the availability of true dual pole units is getting better, I wont go into what I think they do better as it will start a very long debate. I am still looking for the "sat on the fence" smily.

 

[Mike Johnson]

As close as I can find, but looks painful.

 

[pc1966]

If you really need dual-pole tripping because you might have a L-N polarity reversal, etc, then it would need to be really a 2-P breaker (i.e. thermal/magnetic trips on both poles).

Is that a real concern? I guess you always have a high capacity dual-pole RCD incomer anyway due to them all being TT supplies?

 

[Mike Johnson]

The single module units offered in the UK do not have the thermal/magnetic trips on both poles, hence they do not comply with the French Regulations.

The incoming RCD is in reality set up to stop the consumer exceeding the tariff they are paying, there used to be a bit of head room to this, but with the installation of smart meters this head room has been drastically reduced, from what I have been told from 10% to 2%, most consumers who where on the limit prior to the change over have to upgrade their tariff at a cost.

 

[Mike Johnson]

@telectrix

View: https://youtu.be/TUsbRGVVLP0
apologies if you can’t stand Nagy

Interesting to watch Nagy at 2:18 and how much pressure he is putting on his torque screwdriver to get it to click over, seems to fly in the face of those that told me that 2.1N is only just over hand tight.

 

[pc1966]

Interesting to watch Nagy at 2:18 and how much pressure he is putting on his torque screwdriver to get it to click over, seems to fly in the face of those that told me that 2.1N is only just over hand tight.

He may be putting more downwards pressure to stop it camming out the screw head.

I have found that 4Nm is about as much as I can sensibly do single-handed, but that is not while worrying about a pozi screw head (e.g. when using a hex socket, etc).

 

[Ian1981]

Interesting to watch Nagy at 2:18 and how much pressure he is putting on his torque screwdriver to get it to click over, seems to fly in the face of those that told me that 2.1N is only just over hand tight.

I’ve got the same torque screwdriver, you do have to apply a bit of pressure on the 2.8Nm for the Hager mcb,s , Schneider rcbos are from memory around 2Nm so not so much pressure

 

[Mike Johnson]

Of course he is trying not to cam out the screw head, what I was alluding too is the comment made on a different thread that 2.1N is only just over hand tight, you would not need both hands for that, it was a very miss-leading comment when I was trying to find out how difficult turning a torque screwdriver was, I will try to find the thread and post on here, I eventually set up a rig to test my Armeg and found it was way over calibrated and sent it back.

 

[pc1966]

Trying to decribe force is very difficult to do as you need some sort of reference that people have in common, and screwdriver use varies a lot even among engineers. I find 2.1Nm is not that hard to do single-handed, will try to film something later but never posted a video so far so it might take a bit of faffing about.

 

[Mark Wright]

Just a few things i'm throwing out - Rings seem like they would be safer on 20A MCB but I guess there's very few accidents for this to be questioned by the powers that be.

If rings disappeared hypothetically would we loose the fused plug?

I'd be interested in the layout of some European Radials rules and Regs - Spider circuits and what's allowed.

This Hong Kong Code of Practice suggests Rings

Codes of Practice (443)

Training requirements for New Cable Colour Code

www.emsd.gov.hk

I think a few other Asian countrys use them and wonder if they use Fused Plugs

 

[Pete999]

I take it you're allowed to use radials for sockets?

So why does anyone bother with rings, seems like extra hassle to me.

Some places in Pak use RFCs.

 

[pc1966]

Just a few things i'm throwing out - Rings seem like they would be safer on 20A MCB but I guess there's very few accidents for this to be questioned by the powers that be.

You occasionally see rings on 20A fuses (or upgraded to plug-in breakers). They work fine but obviously a higher risk of tripping if a lot of loads on them, and slightly poorer selectivity with end equipment fuses as the instantaneous trip is around 100A instead of 150A.

If rings disappeared hypothetically would we loose the fused plug?

Other way round. The use of the RFC (or lots of sockets on a high current radial) is possible with fused plugs.

Of course it need not be fuse plugs, you could have sockets each with a fuse/MCB to allow an RFC with unfused Euro type plugs, etc, but frankly nobody is going to change systems in the foreseeable future.

I think a few other Asian countrys use them and wonder if they use Fused Plugs

They do. Many former commonwealth countries continued with the old 5A/15A round pin plugs with many radials (e.g. India), or a few moved to the 13A plugs due to ties with the UK extending beyond the post-WW2 introduction of them (e.g. Hong Kong).

 

[Mike Johnson]

In France radials are eight sockets on 1.5mm on 16amp MCB, twelve sockets on 2.5mm on a 20amp MCB, recently been updated to a double socket counting as two, this used to be only one, so there was the possibility of having twenty four sockets on 2.5mm, maximum of eight MCB's/RCD, not forgetting beside the obvious ones, ventilation, well pumps, alarms, heat pumps, UFH, electric radiators, Jacuzzi, Swimming pool, door entrance system, intercoms, electric gates, window blinds, towel rails, washing machines, dish washers, tumble driers and any type of water heater have to be on their own circuit, not sure if they have included fridge's and freezers yet, but there was talk of this, all off the top of my head, so I may have forgotten a few salient points.

 

[Mark Wright]

I have got a copy of L'installation électrique so have to look at that again but I'd love to see some books from other European country's

I have heard of Going from the consumer unit to a big Junction Box then off in every direction but maybe that's just lighting.

 

[Pete999]

T tried to teach the Russian Sparks the RFC theory, something got lost in the translation so much for détente. Left them to to their own ways in the end, I got labelled a Magician by the end of the contract.

 

[Mike Johnson]

I have got a copy of L'installation électrique so have to look at that again but I'd love to see some books from other European country's

My copy is 2016, but nothing on car charging in it, so expecting a revision soon. And they still have the requirement for a telephone point in every room, seems WiFi does not count.

 

[bjouis]

In France radials are eight sockets on 1.5mm on 16amp MCB, twelve sockets on 2.5mm on a 20amp MCB, recently been updated to a double socket counting as two, this used to be only one, so there was the possibility of having twenty four sockets on 2.5mm, maximum of eight MCB's/RCD, not forgetting beside the obvious ones, ventilation, well pumps, alarms, heat pumps, UFH, electric radiators, Jacuzzi, Swimming pool, door entrance system, intercoms, electric gates, window blinds, towel rails, washing machines, dish washers, tumble driers and any type of water heater have to be on their own circuit, not sure if they have included fridge's and freezers yet, but there was talk of this, all off the top of my head, so I may have forgotten a few salient points.

Ah my copy is from 2009 (a mate lent it me) and then you could only use five sockets on 1.5mm and eight on 2.5mm. Should probably get an updated version.

 

[Mike Johnson]

Ah Ha and in that addition any one of the sockets could have been a four gang, so that eight could have been thirty two sockets!!!!! There has been a lot of revisions since 2009 and even then an amendment 5 has been issued to the 2017 regulations.

L'installation électrique - David Fedullo , Thierry Gallauziaux -... - Librairie Eyrolles

Cette bible de l'électricité domestique rassemble tout ce qu'il faut savoir pour réaliser une installation sûre, aux normes, et parfaitement adaptée aux besoins de chacun.Devenu le livre de référence, L'installation...

www.eyrolles.com

 

[pc1966]

In France radials are eight sockets on 1.5mm on 16amp MCB, twelve sockets on 2.5mm on a 20amp MCB,

So they are very much only short circuit protecting the final cables then?

What is the thinnest flex allowed? Even for 1mm a 20A breaker would not be seen as acceptable here.