youcantSomething that I've not seen mentioned: if you put a 13A FCU spurred off from each double socket, then you could connect the extractor fan + cabinet lighting on one spur, and the dishwasher+lighting on the other?
i mount all sockets and built in oven isolators in to adjacent cupboards nothing gets put above the worktops apart from sockets to be used for portable appliancesI'm trying to minimise the number of switches/outlets above the worktop to give clean lines and simplify the tiling. Since the dishwasher has a 13 amp plug I'll mount the socket in an easy to access spot in an adjacent cupboard.
what software did you do that in??Guys, I want to put a few spurs off my kitchen ring main buit am not shure what is and isn't allowed.
I want spurs for the hob extracter fan, dish washer and cabinet lights like this.
First is this allowed, i.e two spurs from each double socket. if yes should they be wired in 2.5mm?
If not allowed, what are my options?
Thanks
View attachment 310923
And you cant do that then?that is why you can only take one 13 amp spur of a ring at any point to balance the load round the ring otherwise you could get a string of sockets down a 10 meter length of the ring and the other half return may be 20 meters with nothing on it
u can but its not good practice having a fair few sockets on the 1st 15 meters of wire and 35m of cable on a return why would youAnd you cant do that then?
PowerPoint, just a bit of cut and paste.what software did you do that in??
They do not and never have saved on material costs, this is a myth!
wikipedia said:that the ring final circuit offered a more efficient and lower cost system which would safely support a greater number of sockets
WHY would you not call them inferior? What advantages do they offer over rings? In a ring circuit current flow is equal in all parts of the ring, if it is BROKEN, it is no longer a ring circuit. Ring circuits break for 2 reasons, someone damages a cable, or they are badly installed.
This test is of purely academic interest, in reality the actual restivity of the conductors is MUCH less than the resistors and this is the reason I said it makes no "meaningfull" difference. Also the resistors will have a tolerance, IOW they will not be all identical in resistance.
Properly installed ring circuits do not just "break" the fact that it is happening today highlights the falling standards of installations, and to some extent the fragility of solid conductor cables
Please explain why? You understand that a radial carries a cumulative current in each leg, so I cannot see how you come to this belief.
This statement is disproved by the massive drop in electrical fires after the introduction of properly installed ring circuits. Also note that ring circuits of today carry nothing like the currents they used to in the days of electric fires and fan heaters.
I agree the short courses are a scam, but nevertheless, the people who complete them are registered with one of the part P scheme providers, most will pass their inspection, and will go straight onto a building site and start wiring houses, which is another reason why consumer units are catching fire, something totally unheard of till recently, and the solution of putting it in a metal box with entry glands and fireproof sealer is such a laughable solution from an engineering point of view, that this alone demonstrates that the IET as an organisation is not fit for purpose. I don.t mind being disagreed with, but give me evidence, not opinions.
Edit, before the ring circuit was adopted, all power including sockets used radial circuits, I thought the ring main had consigned them to the past, I have asked many why they are being reintroduced, never had a satisfactory answer
Phil
, before the ring circuit was adopted, all power including sockets used radial circuits, I thought the ring main had consigned them to the past, I have asked many why they are being reintroduced, never had a satisfactory answer
The 13A Socket, fused plug and ring final sub circuit were developed all together to be installed as a unit, you could equally argue that as the 13A socket was devloped for use with the ring main, another type of socket should be fitted to a radial circuit to indicate that it is not a ring main!Radial circuits are not being reintroduced, both ring and radial circuits have been acceptable since the introuductio of the ring final circuit.
A competent electrician is able to decide which type of circuit is most appropriate for each installation.
It is only the fools who blindly follow the 'sockets = ring circuits' approach.
The 13A Socket, fused plug and ring final sub circuit were developed all together to be installed as a unit, you could equally argue that as the 13A socket was devloped for use with the ring main, another type of socket should be fitted to a radial circuit to indicate that it is not a ring main!
Massively longer post alert!!Long post alert.
In the pre ring days You had a socket only where you needed one, wired as a single circuit with one socket, and with its own switch/fuse. More sockets were often added to the end of the circuit thus developing it into a radial circuit and causing a possible overload. The ring system and sockets were developed to move from this early system to a "socket in every room" system with local fuse protection provided by the different rated fuse in the plug, and coarse protection provided by the 30A fuse in the CU. Because you were wiring a whole house with sockets, as opposed to just the rooms where you actually needed one, it always used more materials, and was never cheaper. BUT "which would safely support a larger number of sockets".The reason I asked was I've heard a few opinions on why rings were used over the years- the information you have quoted appears to come from wikipedia and if you scroll down just a little further you will see it goes on to say (with a citation):
that the ring final circuit offered a more efficient and lower cost system which would safely support a greater number of sockets.
Radial circuits were never used in this way in domestic premises, and generally only had one socket on each circuit, it was later additions to the end of these circuits that turned them into radials.Which was also my understanding - to provide the same capacity and coverage with radial circuits would require more materials. Hence I wondered why you said it was to "cut the number of fires caused by overloaded radial circuits".
These are all advantages for the electrician! Where is the advantage to the householder?To be clear, I am not particularly anti-ring, both radials and rings have their place IMO.
However, radials do offer advantages over rings - they are easier to install, they are easier to test, and if there is a fault it is easier to find.
The only place where I would install one ring is a bungalow, we always installed an upstairs and a downstairs ring. Today it is usually just one ring in an average 3 bed, no advantage to the householder,, but cheaper and easier for the electrician again.You can also design in other advantages for example - replacing a ring with multiple radials protected by RCBO can also provide more selectivity should a fault develop, as opposed to one large ring that knocks out everything.
and to load only one socket on a ring is not a real world occurence, which is why it is of academic interest only!The current flowing in a ring is not equal, it depends where the load is, obviously.
"This installation should be periodically inspected and tested, and a report on its condition obtained, as required by the latest edition of the IEE regulations for the wiring equipment of buildings"If a ring is broken, it is still supplied by the same 32/30A protective device - only now that protective device can no longer protects the cable from overload, and there is usually no obvious sign this has happened unless the circuit is tested
Does this ring a bell?
I agree, the weakness of the ring circuit is only apparent if it ceases to be a ring, this is why good workmanship in installation is required. I was trained on the job and at College that the wires were to be twisted together tightly before they were put into the terminal, and then the terminal screw to be tightened till the brass "squeaked". this ensures continuity even if the wires pull out of the socket, and if you tighten till the brass squeaks, they wont! If I had not done this I would have failed my C&G practical year 1 exam. I understand that today the wires are not twisted together because it makes the ring easier to test, once again, easier for the electrician, but less safe for the householder
Dumbing down? if a ring is installed as above it will not fault unless tampered with or damaged, you can't fight "stupid"Rings can and do fail for a number of reasons, connections can work loose over time or they can be incorrectly altered when work is carried out. On a radial circuit a fault is self evident, on a ring it isn't.
That is your opinion, to which you are entitled. I have seen no evidence for them being safer than a COMPLETE ring circuit. The fact that they are easier to install, use less materials, are easier to fault find are all manifestations of the profit over safety mindset.That's not to say rings don't have their own benefits, but you cannot say they are superior to a radial in every case, as it simply isn't true.
Creative licence? LOL more like VAST exageration. Remember the old IEE reg I quoted "and the whole not to serve an area of more than 100 sqm". This makes 30METRE runs between sockets impossible!! As I said originally, it is of purely academic interest, and bears no relation to real world physics whatsoever!By my calculation each set of resistors in that video equates to about a 30m run - so 180m for the lot. Creative licence perhaps, 100m is probably about the maximum recommended before you start getting into voltage drop.
The above regulation used to make it impossible for such an installation to exist. I am interested however as to why anyone should make this sort of video, using unreal parameters, to try to undermine the value of the ring circuit, and be willing to cheat to do it? 5Metres of cable between sockets is much more realistic, and 100m of 2.5 will wire most modern 3 bed semis even if two rings are used!On the other hand 5kw of load isn't exactly massive. Consider a relatively long, highly loaded ring, perhaps with a string spurs at the end of one leg, and it isn't hard to see how things could get unbalanced - which was really the point of the demonstration.
Neither would you have only one socket loaded in a real world situation!Resistance tolerance is academic, you would never have every socket equidistant anyway, as they explained.
A lot of the installations I have tested have been in service for decades, and still test the same as the day they were installed, I have only seen faults like broken rings on recent installations, and outside of damage or tampering, always caused by not twisting the wires together, which work hardens the copper, not tightening the screws enough, and the favourite one, not leaving enough cable behind the socket. It is also commonplace today to see the back box not earthed and grommets out of place or entirely missing, all of which were instant fails on C&G level 1. It is not rocket science to get this right, but it is essential for safety and I have been horrified to find that some of what I thought were DIY installs were actually very expensive installs done by reputable (supposedly) companies!Nothing is perfect, everything breaks at some point. Cabling can be in service for decades, that's a long time for a lot of things to happen to it irrespective of how well it was installed initially.
I can't imagine there are too many sparks that haven't encountered a broken ring at some point in their career.
I suspect you are overthinking this.
Consider:
A circuit with one 20A rated cable protected by a 16A breaker.
A circuit with two 20A rated cables protected by a 32A breaker sharing the load.
A circuit with two 20A rated cable protected by a 32A breaker where the maximum load is carried by one cable.
Obviously the third one is the problem, Which is why C&G used to have zero tolerance to any faults in workmanship, remember, we were told on starting college, both by our employer and the college, that if you failed the the first year exam, you got 1 retake, then kicked out of college and sacked!All three of these are common scenarios - Which of them is a problem?
This is my point! there has been a worsening of standards, both in materials and workmanship!! The first time I installed a 32A MCB I used the usual torque I would use for a 30 amp fuse, and it broke, the clamp style connector and screw was steel, not brass, and it just could not stand the correct tension to be applied! No I don't remember the days of BC adapters, that was the fifties, but I have rewired many of those houses, and been in them to fault find when you could smell the fault as soon as you walked in the door! Yes they "can" be replace with lower rated radials, but as discussed above, the only advantage of this sytem is to the installer. When ring circuits were installed they all stopped using coal, and started using electricity instead!I think general improvements in terms of materials and standards probably had the most impact on reduction of fires. Remember the days of plugging your iron into a light fitting?
Most ring circuits outside of the kitchen carry very little load in typical domestic environments, which is why they can often be replaced with lower rated radials.
On the other hand, when ring circuits were introduced people mainly used coal for heating anyway and had very few sockets.
We used to call them the "Not Very Qualified" Of course the training courses I mentioned are all NVQ, although they now seem to be £7500 and eight weeks! No part P registered, so who inspects and certificates/signs off on the installations? JIB is synonymous with Pay A Fee isnt it? I certainly never had one and have worked on everything from single dwellings, building sites etc right through to massive factories, industrial plants, engineering works and even laboratories. One of the first houses I ever worked on was a full rewire on Sledmere house, a stately home in East Yorkshire.You won't find a Part P registered on a building site - most reputable sites will require a JIB gold card which requires you to have completed an NVQ or apprenticeship.
Metal clad consumer units are not a bad thing!, I have installed hundreds of them, we used them for shops, offices and business premises, and every grain dryer panel we built got one for the single phase, but to use a metal box to provide a solution to a consumer unit that catches fire is like putting a sticking plaster on the Titanic. It is the tacit admission that they have been wrongly designed, and made from the wrong materials, with the wrong terminations for cables and bus bar, but it will damage our profits too much to put that right, so we will just stick it in a tin box, put some glands in for the tails, and use some fireproof sealer to pretend that will stop the problem, then bring in new regulations so that the responsibility for installing these nighmarish things is on the installer, not the manufacturer!I don't think metal consumer units are necessarily a bad thing, if they are installed correctly. On the other hand I never really saw the issue with plastic consumer units, providing they are good quality and installed correctly.
The issue I have is people ripping out perfectly serviceable plastic CU and then bodging in a metal CU - worst of both worlds. Happens a lot in tenanted properties.
Once again, it is not rocket science! "largely untrained people under pressure" is a recipe for disaster, but not the whole story. I had installed enough of these monstrosities to see the problems up close!There is speculation a lot of fires may have been caused by the push towards smart meter installation.
Largely untrained people under pressure fiddling with the tails and then not checking the terminals are tight in the consumer unit.
I could see that being a factor, some of the smart meter installs you see are nothing short of diabolical lash ups.
Quicker, easier= more profit, safer? again. your opinion, there is no proof here, and although you assume extra safety by derating the mcb, you should check on the reaction time of the MCB's they are nowhere near as quick acting or as current sensetive as most ppl assume, especially if some slow cooking has occured, Bigclivelive has some interesting disections of fired equipment on you tube., and I havent even gone into counterfiet MCB/RCD's arriving from China with all your fave brand names on them!Basically, quicker, easier, potentially safer and satisfactory for most domestic situations. Nothing more complex than that.
Not appropriate for every situation, but a common example would be a ring for kitchen, radials for the rest of the house.
Convention is ,or should be the ring circuit, because the 13A socket, fused plug and ring circuit were designed together to be used together, and in my estimation you shouldnt use one without the other, even though the old style spur was a radial, I always used to try for every socket on the ring, and only used spurs for low demand areas if at all!Convention is still ring final circuits, out of habit if nothing else, and I imagine it will be for many decades to come
What's a radialMetal clad consumer units are not a bad thing!, I have installed hundreds of them, we used them for shops, offices and business premises, and every grain dryer panel we built got one for the single phase, but to use a metal box to provide a solution to a consumer unit that catches fire is like putting a sticking plaster on the Titanic. It is the tacit admission that they have been wrongly designed, and made from the wrong materials, with the wrong terminations for cables and bus bar, but it will damage our profits too much to put that right, so we will just stick it in a tin box, put some glands in for the tails, and use some fireproof sealer to pretend that will stop the problem, then bring in new regulations so that the responsibility for installing these nighmarish things is on the installer, not the manufacturer!
Once again, it is not rocket science! "largely untrained people under pressure" is a recipe for disaster, but not the whole story. I had installed enough of these monstrosities to see the problems up close!
Space, there is not enough room inside them!
It is far too easy to think that the cable is correctly in the mcb/rcd clamp when it actually isnt, even though a tug will not pull it out when new, over time and heat cycling because it is a poor connection, it will come loose, and get hotter
Same applies to the stamped copper bus bars, they must be assembled in to position very carefully in order to ensure full clamping on all the lugs.
Design of the terminations! What is wrong with a solid block of brass with a hole in it, and two well engineered screws to clamp the cable or buss bar? Nothing, but it is too expensive, so it has been reduced to a brassed steel screw and a bit of pressed metal which is very easy to break, as I found out! Torque screwdivers is another "Titanic" solution, you tighten it too a click which is set to be just below the breaking point of the termination!
All these thinngs cause heat in the terminations, which is the absolute enemy of all electrical terminations and must never be allowed to happen! When it does happen, it slow cooks the electronics inside the Mcb/Rcd and when a fault occurs, they dont trip. and owing to the fact that the IET ignore the old IEE regulation about no mechanical device being used as a sole means of protection, or using the excuse that there is actually a fuse, albeit a 100amp one, and you have a consumer unit with a faulty circuit which is carrying 100+ amps on a cartridge fuse which will blow when the current gets up to about 130 Amps, but of course the consumer unit and the MCB/s are made from flammable materials, where as the old wylexes were made from non flammable phenolic resin, and hey presto, your CU becomes a volcano! From the workmanship point of view, should the equipment be designed so that it is VERY difficult to make a mistake, rather than quite easy? Of course it should, and it used to be!
Quicker, easier= more profit, safer? again. your opinion, there is no proof here, and although you assume extra safety by derating the mcb, you should check on the reaction time of the MCB's they are nowhere near as quick acting or as current sensetive as most ppl assume, especially if some slow cooking has occured, Bigclivelive has some interesting disections of fired equipment on you tube., and I havent even gone into counterfiet MCB/RCD's arriving from China with all your fave brand names on them!
Convention is ,or should be the ring circuit, because the 13A socket, fused plug and ring circuit were designed together to be used together, and in my estimation you shouldnt use one without the other, even though the old style spur was a radial, I always used to try for every socket on the ring, and only used spurs for low demand areas if at all!
Phil
It was in response to your casting aspertions on my competence! No offence intendedNo you couldn't argue that, it is quite obviously a ridiculous suggestion.
A radial is a circuit where a single cable leaves the consumer unit and goes from socket to socket but ends at the last socket.What's a radial
What's a spur.
And what's a ring main.
I think I know. But just in case..
The old wylex units also had a wooden base and rewirable fuses, nice and safe!Metal clad consumer units are not a bad thing!, I have installed hundreds of them, we used them for shops, offices and business premises, and every grain dryer panel we built got one for the single phase, but to use a metal box to provide a solution to a consumer unit that catches fire is like putting a sticking plaster on the Titanic. It is the tacit admission that they have been wrongly designed, and made from the wrong materials, with the wrong terminations for cables and bus bar, but it will damage our profits too much to put that right, so we will just stick it in a tin box, put some glands in for the tails, and use some fireproof sealer to pretend that will stop the problem, then bring in new regulations so that the responsibility for installing these nighmarish things is on the installer, not the manufacturer!
Once again, it is not rocket science! "largely untrained people under pressure" is a recipe for disaster, but not the whole story. I had installed enough of these monstrosities to see the problems up close!
Space, there is not enough room inside them!
It is far too easy to think that the cable is correctly in the mcb/rcd clamp when it actually isnt, even though a tug will not pull it out when new, over time and heat cycling because it is a poor connection, it will come loose, and get hotter
Same applies to the stamped copper bus bars, they must be assembled in to position very carefully in order to ensure full clamping on all the lugs.
Design of the terminations! What is wrong with a solid block of brass with a hole in it, and two well engineered screws to clamp the cable or buss bar? Nothing, but it is too expensive, so it has been reduced to a brassed steel screw and a bit of pressed metal which is very easy to break, as I found out! Torque screwdivers is another "Titanic" solution, you tighten it too a click which is set to be just below the breaking point of the termination!
All these thinngs cause heat in the terminations, which is the absolute enemy of all electrical terminations and must never be allowed to happen! When it does happen, it slow cooks the electronics inside the Mcb/Rcd and when a fault occurs, they dont trip. and owing to the fact that the IET ignore the old IEE regulation about no mechanical device being used as a sole means of protection, or using the excuse that there is actually a fuse, albeit a 100amp one, and you have a consumer unit with a faulty circuit which is carrying 100+ amps on a cartridge fuse which will blow when the current gets up to about 130 Amps, but of course the consumer unit and the MCB/s are made from flammable materials, where as the old wylexes were made from non flammable phenolic resin, and hey presto, your CU becomes a volcano! From the workmanship point of view, should the equipment be designed so that it is VERY difficult to make a mistake, rather than quite easy? Of course it should, and it used to be!
Quicker, easier= more profit, safer? again. your opinion, there is no proof here, and although you assume extra safety by derating the mcb, you should check on the reaction time of the MCB's they are nowhere near as quick acting or as current sensetive as most ppl assume, especially if some slow cooking has occured, Bigclivelive has some interesting disections of fired equipment on you tube., and I havent even gone into counterfiet MCB/RCD's arriving from China with all your fave brand names on them!
Convention is ,or should be the ring circuit, because the 13A socket, fused plug and ring circuit were designed together to be used together, and in my estimation you shouldnt use one without the other, even though the old style spur was a radial, I always used to try for every socket on the ring, and only used spurs for low demand areas if at all!
Phil
As I thought. So you can have spurs of rings and radials?A radial is a circuit where a single cable leaves the consumer unit and goes from socket to socket but ends at the last socket.
A spur is a radial circuit, one end of which is connected to a ring for its supply, and the other end stops at the last socket
A ring is a circuit that leaves the consumer unit MCB and goes from socket to socket, and then from the last socket it returns to the consumer unit and is connected to the same MCB.
Yes.As I thought. So you can have spurs of rings and radials?