KNOW HOW: How does current divide in a ring final circuit? (ring main)
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- Опубликовано: 15 май 2024
- The ring final circuit (ring main) is a unique British socket wiring system. More complex to test and install compared to radial circuits. In this electrical tutorial, Joe Robinson explores how the current flows in the branches of a ring circuit.
This video demonstrates why you can't use a 16A junction box on a 32A ring final circuit, a topic explored in a previous electricians' Q&A - • Can a junction box rat...
🕐 TIME STAMPS 🕕
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00:00 Ring final circuits - (yes loads of people still call them ring mains)
00:56 Ring final test rig.
02:00 Load placed in the exact mid-point.
03:35 Placing load away from the electrical mid-point.
04:50 Placing load close to the consumer unit.
05:50 Appendix 15 - BS7671
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🎦 Presented by
Joe Robinson - technical editor eFIXX
#efixx #morepower #BS7671 
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Visual explanation always has more impact for me, thanks.
Me too, glad it helped. 😊
Lp
That's why I like being an electrician, you learn new things all the time.thanks
Such a clear explanation! I love it when you can clearly demonstrate the science and the simplicity in which it is explained.
Brilliantly well illustrated! Thank you.
Another great demonstration video by Joe explaining the reason why load should be split equally between the legs of the ring final circuit. Also like the reason why 16amp junction box shouldn't be used. 👍👍👍
Thanks very much!
Excellent demonstration!
Well, you've just won my subscription. I'm a competent DIYer (I always get everything tested and verified by a qualified spark), but while I knew the vague theory of this I could never quite get it straight in my head why. Awesome demonstration!
A twin and earth cable leaves the fuse travels round all the sockets and returns back to the fuse again. Not that hard
@@Steveuploads And yet hard enough that you completely missed the point of the video, well done you.
Best explanation I've seen for a ring circuit, like the use of power resistors 😃 Using a thermal camera would also allow the demonstration of heat in a cable.
Great 👍 idea
Excellent demonstration, well done
That's an excellent demo/video. Hope to see more like this. Very informative.
Thanks Chris, stay tuned. 👍
Excellent and very informative, thanks!
Brilliant vid and explanation. Thank you very much and keep them coming.
Totally brilliant, just doing a course at the moment, this really supports my learning👍👍
Brilliant explanation of this problem. thank you
Wow, Brilliant demo and nicely explained, many thanks!
Thanks for the very positive feedback 👍
Bang on.
Which proves the point that when installing an appliance grid plate on say a kitchen ring final circuit it needs to be approximately in the centre.
#toptip
Your "temporary test examples" are of a level of impressive quality.. Only thing missing is some plasterboard and some paint.
Great explanation that people still do not get!
At college we were always taught to balance rings as best as possible for even distances between sockets. Rings were never designed for high loads too.
Excellent video, as always!
Good explanation and reminding folk that the current flows in both legs of the ring. When I had the house gutted out and insulated the electrician was told to increase the diameter to 4mm2 due to the interior wall insulation (Aerogel) he asked if I wanted a return leg or a radial, for the extra half an hour labour I had a return leg. The only benefit of the ring I found is the voltage of the last device is more consistent. Given the cost of labour of the electrician vs. the cost of the wire, I'd much rather have the resistance in the appliance than in the wiring and interconnects. The 32A breakers (20A would be frustrating and prone to nuisance tripping and failure in the kitchen) protect the wire from shorts leading to fire or overload leading to excessive joint heating/conductor insulation melting->short and fire. I suspect we'll end up with panels and steel conduit with radial finals each with its own RCBO, a much more professional and industrial setup.
Another great vid guys
Really enjoy these videos very helpful and informative keep them coming guys
Thanks very much and we will! Stay tuned!
Great video very educational and helps a lot thanks keep up the vids👍
Great experiment and demo thanks
Excellent. Well explained Joe.👍🏼
Thanks Kevin. Much appreciated. 👍
Try explaining this to a client so insistent on plugging in a lazy spa on a spur because “well it can’t be that bad it’s on a 3pin plug”?!
Great video 😊👍
My neighbour had a lazy spa set up in the shed plugged in to a 10amp extension which was plugged into a kitchen socket. Lots of melted equipment the next morning.
For sure! Show them the video! 👍
I bet!
May I suggest eFixx is for you to maybe perhaps do a video using laymans terms without the jargon where electricians can direct their customers to visually explain to their customers re the lazy spa issues regarding the risk of melting components and what the solution would be to ensure safety of supply and to occupier of the property?
Try telling this to the suppliers of said lazy spa who don't seem to care if the customer plugs the damned thing in via an extension lead........... I have been called out to multiple melted outlets.
Interesting. I was involved with Power Line Communications about 20 odd years ago and did some modelling of a ring main using transmission line and two port network theory.
I like it! Nicely done. Thanks Joe👍
Thanks very much! 👍
Excellent Upload.
Message received !
Very interesting!! Well done
Great presentation and information. Many thanks
👍🏻
Great video idea. Weldone guys!
Thanks very much. 😊
Very good video well explained! Would love to see a video showing how to properly cut and lift different types of flooring to rewire etc please
Good luck with a tiled concrete floor! 🤔🙄🤣🤣
Great demo. Makes you think that say in a kitchen with a kettle, toaster, washing machine and dryer all early on in a ring final circuit, followed by above counter sockets, most of the current will be flowing through a single 2.5mm twin and CPC cable.
That is exactly the point David. 👍👍👍
That's exactly why a kitchen should be a dedicated circuit
Had to put in a 4mm spur for my under the sink 4kw water heater, so brought a whole reel of cable as it always useful, and my mate electrician said best upgrade anyone could do is go 4mm through whole property in this day and age, my little kitchen alone has 15 sockets/switch spurs , rest of my flat I put a switch double every 4ft apart with 2 doubles in corners where TV could go , one corner upgraded to 2 triple sockets, every room has it's own ring main , put a 6mm armour cable to my garage 4 was plenty but 6 even better 😀 for more tools and toys to power.
Absolute brilliant video!
Thanks
Great presentation, thank you 👍
You're welcome, thanks for commenting. 😊
Nicely explained by efixx.
A fan from India who strongly follow British Standard rather than Indian standard.
Thanks Mohammed 🇬🇧
When installed like below the igneous & simple final ring circuit now is near *bombproof:*
*1)* Use an AFDD in the CU (regs recommend them);
*2)* Use screwless terminals on the sockets;
*3)* Use 4mm cable;
Having a ring like this would eliminate a multitude of radial circuits, all with their own AFDD and eliminate a large CU cabinet. All reservations of a final ring splitting creating two radials on a 32A breaker and arcs created due to loose connections are gone.
I have seen one and two bedroomed flats in London with heating on a gas combi, wired with *three* circuits:
*1)* Final ring as above, in 4mm;
*2)* An RCBO on 4mm cable to a 13A hob and 3kW oven (both with 20A isolator switches in adjacent cupboards;
*3)* 3A RCBO for the LED lights on 1.00mm cable.
*4)* Small and cheap CU box with a spare way.
Only 4mm and 1.00 cable was used.
If this was in France it would have a large main panel with many, many needless radial circuits. Regs in France state the maximum number of socket on one radial is *eight.* I have 12 in my living room alone. In France that would be two radials for one room. Madness, when rings are here.
Circular is the way to go! As you prove the point here.
Hi what spec power resistors did you go for in this rig?
Great explanation sir! 😁👏
Thank you sir!
Excellent video. Great explanation and demonstration. I wasn’t a spark and now I am.😂 It’s made want to unplug a load of equipment now though.
😂 Glad it was helpful, sorry to increase your paranoia. 😬
Thanks. Very informative
Our pleasure, really enjoyed making this one.
This is a very good way for people to get a practical understanding of the way electricity operates in circuits. Have you done any videos showing the same for radial circuits and spurs from ring and radials at each point along the circuits? that would be really good and would help explain why certain decisions are taken. Digging down into the current for the increased loading, I am not quite sure how that has come out at 16.5A on the bottom leg as the ratio of resistance for that socket is 0.22 vs. 1.1 on the other leg. Based upon a 5KW loading, which equates to 21.7A, 5/6 x 21.7A should come out at around 18.1A in the bottom leg vs approx. 3.6A in the upper section. I wonder what that would have been...
Excellent explanation
Thanks
Brilliant explanation joe, it certainly if food for thought that unevenly spaced sockets on a poorly wired ring, could potentially overload a single leg of 2.5mm t&e.. you can imagine the scenario, kitchen ring with kettles, toasters washing machines and maybe a hot tub on an extension lead into kitchen all backed up on a 32A MCB with a single 2.5mm cable rating in the region of 27A🔥🔥 it begs the question, Why have they been allowed for so long? surely the radial circuit is the way to go in the future👍
Thanks very much. And it certainly is thought provoking. The last house I rewired I actually didn't use any ring final circuits, only radials. 👍 By the way is it Daddy B on your birth certificate? 😂
Yes that is correct, daddy b🤣👍
😂👍
Good explanation, however you have to remember that ring mains generally have loads of varying types plugged in throughout the whole circuit. When that happens the load is more eventually distributed than loading up one socket with one heavy load. Naturally one leg will probably carry a bit more current if the loads never change sockets and nothing else added. The routing of cables, some possible tight bends and yes not such good solid connections, will have an over all affect in the current in each leg. Higher resistance causes a bigger voltage drop, proportional to current through the cable / connection.
From memory, the BS standard for double sockets only requires them to run at 20A total for a sustained period, so that's a bit less than 5kW. I suppose that there's nothing stopping somebody actually plugging in two 3kW space heaters into the same double, but it's probably unusual. Things like kettles, Wahing machines, toasters and so on are less of an issues as they aren't sustained loads (most of a washing machine load is the water heater and the only run at full power for a few minutes).
@@TheEulerID Yes sounds right Steve. One has to consider “Cannabis Farms”, high current lamps plugged to every socket with extension on extension ?!, perhaps we need a review of the British Standards to take account of the continuous current …. :-)….. all the best to you …
Another great video explanation,
I have seen this type of circuit extended at a later date useing blue inline crimps in the back of a socket outlet.
Is that compliant?
On many commercial jobs these circuits are wired in 4mm conductors , "belt & braces !"
And what size feeder did you have on that DB when you connected 5KW????
Looked 1.5mm tastic to me.....
Great video, confirms I still need to deploy Final Rings because they work well, but poss use bigger string?
Excellent video, you get a good length of circuit with a Ring final. You are limited to length with radials.
Amazing thank you
Great teacher
Nice one guys
Great video .
Thank you!
Great demonstration 👍
Thanks Richard. 😊
Superb video
Thanks James. 😊
Clear concise information. Understand the less or more resistance in the ckt.
STILL trying to understand the INSIDE Of the CU Consumer unit of the Ring.
Is this the SAME as a Split Phase in North America wiring?
Thank you.
The CU is a single phase 230vboard. The two live legs of the ring are connected to the MCB OR RCBO, and the two neutral kegs are connected to the neutral bar in the case of an mcb, or to the neutral terminal of the rcbo. Hope this helps
Looking at rebuilding our house. Having recently bought a new build it’s got a mix of radial and ring. What’s the right option
Current going in = current going out. Kirchhoff’s current law. Nice visual demo.
Okay, please explain what happens when a load is plugged in two of the outlet boxes. What current flows through the middle link between each outlet?
If the loads are equal do we see no current flow between the two outlets, only on each leg back to the breaker box?
Very nice explanation, which has made me question my (just being built) kitchen island electrics. I have brought the ring into the island and there was an existing spur from this junction to the fridge feezer. I want to add a double socket for kettle and toaster, and a single for the dishwasher. Is it better to make the new sockets spurs or part of the ring?
Doesn't matter. Just do the current calculations and ensure you don't overload the cable or breaker. At the end of the day, you are running a spur of the ring so the current is passing through the ring.
The downside of extending the ring to the new sockets is you need two lengths of T+E cable, whereas if you add a spur and fit the socket on the spur, you just need a single length of cable.
You’ve overloaded that 13a double socket there, naughty naughty 😉
Great video on ring mains. Showed the path of least resistance concept brilliantly 👍
Yeah, I’m just pulling your leg 🙃
Actually it’s a great video. Are you planning on showing how a radial makes much more sense? And showing example of 4mm, 6mm and 10mm etc just to drive the point home?
Also, my bugbear with “rings” is that I’ve see many rings that aren’t rings anymore (N or L wire hanging out of the back of a socket). So two radials on a 32MCB 😧
Thanks 🙏
Couldn't agree more. 👍
"Path of least resistance". I have seen this phrase used by qualified electricians and it is such a poor phrase that we should stop using it.
The phrase gives rise to a misunderstanding that where there are multiple paths for the current to flow, that it only flows along the path of least/lowest resistance, and that is just not true.
The current flows through all parallel paths, and the way to calculate what current flows along each path is by using (1) 1Rt = 1/R1 + 1/R2..1/Rn for n parallel paths/ resistances in parallel and (2) R=V/I, and (3) ΣIn =0
where do i take the neutral feed from in a 3 phase circuit which doesnt have a neautral?
What distance do those power resistors represent?
Question what's that cable rated too?
Let me thank you , I have this question long time ago, current will not go totally in the less resistance path , instead it will be divided proportionally between the ring-two paths, that's it , thank you again
Really interesting video. I always assumed that the load is divided equally. Would love to see part two to this. Where you power the socket next to the other one. Could you have an example where you could overload the 2.5mm conductor on one side of the ring. How many amps can 2.5mm take?
27amp
Great video 👍. Would you say any Junction box under 32A is unacceptable? I've seen a well know electrican youtuber use 24A wago connectors and he used that reason of the load being split down each leg?
I believe i Am correct in saying BS7671 states that conductors of a ring final circuit must have a min ccc of 21a so I would assume a joint of a rating exceeding this requirement is satisfactory. As joe mentioned there is only so much we can do.
Joe mentioned in a previous video that by the regs, the connection should be rated to no less than 20A. The Wago 222s, to which I believe you refer, are fine for this.
Great vid Joe ... Will you be uploading new vids to your channel anytime soon ?
The content on this channel is Joe’s content. We upload 3 videos a week every week 👍. Thanks for commenting. Team eFIXX 👍
Excellent, will there also be electrical theory themed videos ?
Interesting result. A 2KW load at 230 volts implies a resistance of, what, about 30 ohms approx? So one's first thought is, well, the ring main voltage is pretty much the same everywhere and the wire resistance is relatively much smaller than the load, so it shouldn't make much difference where in the ring the load is placed. But of course when you draw the full equivalent circuit (which you sort of did in the model), Kirchhoff''s laws come into play and the result is a bit unexpected!
Awesome demo thanks. I'm no electrician but have a keen interest, could you explain as to why this is worse than having a radial?
I'm guessing from the tone in the description and some of the comments that this is not the preferred method but even recently my spark said we should always do rings for sockets. Thanks.
Because they can carry twice the amp compared to radial....unless u use 4mm radial sockets.. ..and also if one side of ring damaged there will still be power..
@@whitebeltlyfbjj3393 That is the issue. Ring can fail without actually losing power. The load handling of the circuit is then halved (and there might be something even sketchier going on in the place where the circuit failed) but there isn't a loss of power to the circuit.
When a radial circuit fails you won't get power until you get the failure fixed and that's how it should be.
Your sparky is wrong mate.
Since copper had a positive temperature coefficient (resistance increases as temperature increases), does that help balance the current in a ring main in a way that wouldn't be demonstrated here? Or is the effect so small that it's irrelevant?
It has only a minor effect.
Can you show how to calculate on your board current flow in a ring circuit if you dont have a clamp meter.
Brilliant Joe. Where have you been!
I've been here the whole time! 😊
@@efixx About time you had a holiday.
Kitchens are where ring circuits are useful - my kitchen has toaster, kettle and Microwave all in same area
Greetings from Finland.
Question: Why there is only one 32A fuse/circuit breaker protecting both legs of the ring? Of course that's the way ring circuits were made in the 1940's but wouldn't it remove all the safety hazard from the ring final circuits if there was one 2x16A circuit breaker (so two breakers but internally connected together, if one trips -> the other one trips as well).
The idea here is that you would connect one live lead to one circuit breaker and the the other live to other circuit breaker. If the ring would go off-balance enough, more than 16A would be drawn from one live wire and it would trip the breaker. However if you have perfect balance in the circuit, you still could draw 32A from the whole circuit but you are not overloading any of the wiring.
I don't know what is "normal" current rating for 2.5mm^2 in UK but here in Finland we use usually 16A breakers for 2.5mm^2 wiring.
This is something that if there is no real reason not to do this, maybe something like this could be enforced in future regulations to make ring circuits more safe.
Ring circuits are VERY safe, a cable rated at 27A (ie 2.5mm²) will not burst into flames if loaded to 30A! It will simply get a bit warmer than the rated 60ºC but that takes time, and the breaker will warm up too and trip long before any cable becomes hot enough to ignite wood next to it. A dual 16A breaker solution would solve a problem that doesn’t exist, and cause lots of nuisance tripping. Ring circuits have worked extremely well for decades
@@edwardemberton8069That raises the same question though: why not 2 27A breakers (or whatever most closely matches the rating of the wire) setup to trip each other? Could increase total possible amperage on the circuit for balanced loads, while still preventing unbalanced loads or ring breakages from exceeding the rating of the wire?
A kitchen ring is the only ring circuit likely to get loaded up in a house environment!
You mentioned a kettle and a toaster produced your load!
Both items will only be on for minutes at a time!
A dishwasher,dryer and washing machine are often on together in my house often along with the kettle, probably over 30 amps on occasion as the machines go through their cycles?
Rings are safe otherwise 1 in 10 houses would have a fire daily! Piss poor maintenance and installation by a kitchen fitter should worry people
There is a video somewhere on RUclips (I don't remember where and i don't know whose channel) where a spark is baffled that a ring circuit has been wired with cable not running from outlet to outlet consecutively. Some of the comments for that video point out that this used to be common so as to create even distribution of current throughout the circuit (as much as is possible).
An interesting sequel to the video here, would be to run the cabling in this way. So, socket 1 is connected to socket 3 etc and the return leg doesn't return from the extremity but somewhere in the middle and repeat the demo.
If I could find the video, I'd post the link🤔
If you watched it it will be in your youtube history (if you are signed in and have keep history turned on)
@@Apex180 I know. I watch so much of it though, it'll be like trying to find a needle in a hay stack. I really need to get a life😂
@@kendoknackersackee was it this one by David Savery perchance? ruclips.net/video/GlUlSQrneCU/видео.html
@@drunkkmachine4511 Well done Chris, I believe it was. Thanks mate👍
Someone in the comments called it the kangaroo method😂
David Savery mentioned this in a fault finding video, where he found the way the ring was connected unusual.
I remember at college we were told about DIY people, accidentally creating a ring with in a ring. Possibly by extending the ring but not braking it first(attaching a new ring between two different sockets). This is obviously incorrect! But I argued the it won't harm the current handling ability of the ring circuit. Its just more parallel copper added. My college teacher said it was dangerous, but I can figure out why. I know it will make it impossible to test the new B/8 shaped ring.
I wander if you wired the ring final in a different way. Say, hit miss fashion (socket 1-3-5/2-4-6 join the end) would make any difference in the load split
That method is recommend.
Lol I commented on this video a year ago. Literally this video showed up in my suggested videos again and I was just about to comment the exact same thing 😂 in a radial circuit, you plug the toaster and the kettle in together and you will draw more than 16 amps through the cable. No, of corse you can’t just slam a 16 amp junction box on the Ring Final circuit to extend it, but you can’t in a radial either. 2.5 mil cable can more than handle 20 Amp. 2.5 mil in a ring can handle almost double becuase although the load isn’t split evenly, it’s still split. 16 amp is negligible. In a radial however, you can handle 20 amps no problem but as you said, you only had 2 appliances hooked up (the two main power eaters btw) 16amp is getting quite close to the cable’s limit when you consider adding more load to it at the same time. So you need to then upgrade your cable to 4 mil which is more expensive and harder to work with before you can upgrade your breaker to 32 amp. I don’t see how you can hate on ring final circuits. They are cheaper, safer and easier to work with. They just require you to actually do proper work on them when you change things. Or you could be a decent guy and plan for changes in the future and accommodate them in your design. It’s not hard.
Have the ring circuit on an AFDD, screwless terminal sockets to avoid loose connections in time, and 4mm then it is near *bombproof.*
On a radial on full current draw all the current is on the terminal of the first socket on the radial. If an earth cable is severed for some reason on a radial there is no earth back to the CU, yet the ring has two earth ways back to the CU, so safer.
A 2.5mm final ring circuit should ideally have no more that 20 amps on each leg. See wiring regs Chapter 4 appendix 15.
If you are _a decent guy and plan for changes in the future and accommodate them in your design,_ then cable the ring in 4mm. 4mm is easy to work with if Wago connectors connect the ring in a backbox, with 2.5mm flex to the socket off the Wago. Easy to push back the socket. Also use the Wagos for 1st fix testing leaving them in the backboxes ready for socket insertion. Using Wagos means the ring current only runs through the spine not via the terminals of the sockets.
You can fit in a *_balanced_* ring circuit.
It goes like this:
*1)* From CU's MCB or RCBO, run a cable to the 1st socket on the ring;
*2)* Then *do not* run a cable to the next socket, the 2nd. Run it to the *3rd,* then the *5th,* etc. Alternating;
*3)* Then the second cable from the CU's MCB or RCBO, run to the *2nd* socket, *4th,* etc. Alternating;
*4)* Then at the end join the two cables up at the last socket;
*Then you have a* *_balanced_* *ring.*
It does not matter if the ring is not balanced. This isn't a 3 phase system where there is a requirement to balance it. The only thing that matters is you don't exceed the maximum current carrying capacity of the cable when it is not balanced.
@@deang5622
Correct.
But if it is heavily out of balance one cable on one of the legs can have its current limit *exceeded* if a number of heavy appliances are used.
If it looks like this can occur there are three way of solving it:
*1)* Balance the ring as I explained in the above post;
*2)* Run 4mm cable on one leg to the outlets of the final ring that will take the heavy load. For e.g., if the first three outlets on a ring say will have a tumble dryer on each, then run 4mm to the first three sockets. Then 2.5mm is fine for the other leg, which is the rest of the final ring;
*3)* Run all the 32A final ring in 4mm cable.
*1)* above is the cheapest, then *2).*
Based on this example is it therefore possible to overload a 2.5mm cable in a ring final by putting a lot of load at one end of the circuit?
No because it is fused at 32 amps . As the short leg heats up its resistance increases sending more current the other way
Screw caps? Bin 'em!
I used to think that till Blu-Tac!
Can a ring circuit be put into a 16amp breaker if the Zs is too high for a 32 amp?
Yep. IIRC, to current regs *minimum* of 2.5mm cable and *max* of 32A breaker (MCB, RCBO, AFDD).
A ring circuit can be in no more than 100 square metres of floor space, with the cable no longer than 100 metres in length - the 100-100 rule. If the ring is long, use 4mm cable to get the resistance down and avoiding an unbalanced ring.
Nice video. Perked up when I heard you quote, current is inversely proportional to the resistance. Anyway, regarding loads when balancing the circuit, you have no control over what is plugged in, unlike for fixed loads. Not criticising, just thinking. Which is what all your videos do to me. Again, nice video.
I have just installed a Emporia Energy Monitor to my consumer unit. The installation guide said to put a clamp around only 1 wire on the ring. Then in the App you can double up the result ( x2). Now having just watched this very good and informative video, i can see how i can get very inaccurate results. Should i put the clamp around both and delete the x2 factoring…. Is this better ??
Yes you’d have to clamp around 2 to get an accurate result.
As long as you are putting the clamp around two live conductors and they are both of the same phase, then there is no problem doing that and you will measure the total current in the cables.
Once did a course, where we were told to look up the data for double sockets, pointing out that a double socket is only rated to 13amp across both outlets, and that overloaded sockets in kitchens were commonplace. Apparently tested to 1.5times the design limit (i.e. 19.5 amp).
A double socket is rated to 20 amps
@@persona250 not according to the manufacturer's that I consulted about it. I did a design for a resin workshop where they were using 2kw heaters with moulded plugs for keeping the room hot enough whilst waiting to be used, and part of the process required banks of 2 side-by-side. I consulted the manufacturers of the kit we were using at the time (think it was maybe MK), and their tech guy said that they were tested to 1.5x the rated current, and they were rated at 13amp, but the rated current should not be exceeded. We tried another couple of manufacturers to see if we could do it, and all came back with the same response. Most tested to the rounded up 20amps instead of 19.5amps. Funnily enough, they have stood the test of time, unlike another similar room on site where the sockets had to be replaced with FSU's as the sockets and plugs had all over time melted or burnt out, preventing switching off, or function at all.
@@iandonnelly542 BS 1363 states a double socket should be rated to 20 amp minimum
@@persona250
But two 3kW appliance can be plugged into the two sockets on a double, drawing 26 amps through the double.
@@johnburns4017 correct john don’t shoot the messenger. 3kw appliances should be on there own individual circuits…
More Powaaaas 👍
An electrician recently discovered my house had a ring circuit wired incorrectly with each leg of the circuit going to two different 16amp mcbs. He changed this so both of the legs run to one 20amp mcb.
Would love a video explaining why this is dangerous
You do not need a vid to explain that.
Before many think they are going to have a fire.....
Yes, there are *advantages* to rings. They have been widespread in the UK for 75 years. They have been found to be *very safe.*
♦ Cheapness, as smaller, easier to install, wires can be used;
♦ Two ways for the earth back to the consumer unit;
♦ Another is a large number of sockets can be off one cheap ring;
♦ Having the same number of sockets using radials would mean multiple radials and multiple extra breakers at the main panel. Far more cable, expense, labour and hassle;
♦ The 32A breaker and 13A fuse in the plug ensures safety.
♦ Portable plug-in appliances on a ring cannot exceed approx 3kW. Some plug-in ovens are on rings;
♦ Rings usually have a 32A breaker at the main panel - can be a smaller value;
♦ Using push-fit *maintenance free* Wago type connectors to connect up the ring makes them a lot safer as not being screwed connections they do not work loose. The ring's current does not run through the socket terminals;
♦ The British plugs are designed with rings in mind having a _max_ 13A fuse in them - can be as low as a 1A fuse in the plug to suit the appliance. Small flex and appliance? Then a smaller fuse;
♦ Rings in the UK are limited by square metres of floor space, with no limit to the number of sockets on the ring. 100 square metres of floor space for 2.5mm cable for a 32 amp final ring .
Radials are also used in the UK, rings are not mandatory, but used because they are generally trouble free, safe. They can be installed using *rule-of-thumb.* These days a ring will be on an RCD or RCBO - these now are becoming DP, so safer again. In one job in an office, they wanted more socket outlets for extra desk computers. It was a simple matter of extending the existing ring with the extra sockets as the current draw was low. Cheap and easy. If radials were used three radial circuits would be needed, which would mean an extra consumer unit, breakers, wire etc, then far more labour.
Some *disadvantages* are:
♦ Rings are more difficult to fault find. But electricians have no problem once the ring is full understood;
♦ Another is that if a number of high current drawing appliances are on one side of the ring, say near to the main panel, most of the current draw may be down one cable of the ring which is rated below the main 32A breaker. 2.5mm cable is rated at 27A max. Although tests have proven the cables do not exceed their current capacity, just an imbalance in distribution of the two cables from the main panel (consumer unit). *Good circuit design will prevent this, negating this* *_disadvantage._* Balanced rings can be installed by daisy chaining to _alternative_ socket outlets on the ring. That is the first appliance will draw from one side of the ring, the second socket will draw from the other side, and so on round-robin. Or use 4mm cable to the point where heavy current drawing appliances are then 2.5mm for the rest, if it is that troubling for some. Using 4mm cable on one side of a ring and 2.5mm on the other, is still cheaper than a bunch of radial circuits.
Overall I consider one ring superior to a bunch of radials needing their own breakers at the main panel. They are simpler, cheaper, being proven to be safe and worked well over the past 75 years. You will have to give a very convincing argument for me to give up rings. I have not heard of one yet.
Shhhhhh...... we all knew this really but our beloved NICNIC will have us adding tertiary cabling now it's been brought to their attention.....
I’m sure they’ll sell you a course first!
God I am glad the UK is the only country with Ring circuits
The rest of the world is missing out.
Does this hold true for 120 volt single phase systems?
The principle holds true for any voltage, but local code would not allow it, mainly because there is no fuse in a 120V plug so the breaker has to protect the appliance too. A 32A breaker protecting a bedside lamp cable would be dangerous, but the UK system has a 3A or 13A fuse in the plug
My house is a 70s build with a 17th edition fuse box. (had new box installed when I moved in)
All my lights are split into two rings and breakers. However, my sockets are all on one ring circuit with a few spurs. Should I be worried that my sockets are not split into upstairs and downstairs?
This is how the house was wired in the 70s.
Your house needed a full rewire 20 years ago...
@@Emin3m1986
Why? cable can last and last. There is no time date on it.
@@johnburns4017 - yeah, the older is... it gets better, like wine :))
Put an Amp Clamp on the ring cables at the CU, with the most appliances all on. If a heavy draw, then _maybe_ run in a few radials for the heavy kitchen appliances.
Best have the dishwasher, washing machine, etc, on their own RCBOs. Safer, as one cable to each with screwed connections at each end.
Your lights are not on rings, they are radials. The breaker will trip before there’s a problem, if it ain’t broke then don’t fix it! PVC lasts nearly indefinitely, rubber perishes at the ends, your electrician would not have fitted a new fuse box if the wiring was unsafe
Hi . Why this type of circuit is used alot in uk what's makes it used from decades is there a clear reason to be use or is there a story of it ..
Here’s the full story
en.m.wikipedia.org/wiki/Ring_circuit
@@efixx
Thanks.
The penny dropped for me when you said that the current is split in inverse proportion to the resistances. I immediately thought of lightening, does that mean that current is actually travelling through every possible route to the ground, but it's only visible when the current is over a certain amount? enough to ionise the air or something?
No. The resistance of air is very high, until the electric field strength across it is high enough to cause an avalanche breakdown, in which point the resistance drops massively and the current flows through that ionised channel.
Is there such thing as 32a junction box instead?
You can get 32a junction boxes
@@efixx Yes thanks. It would it work well is the operative question? Lol.
4:31 FINALLY. Somebody said it!