Yikes, blown the suppy company neutral fuse ...

Extra sockets 15A and 5A) were fitted to my parent's house in 1957. A new fuse box was installed with double pole fusing, and TRS cable. This was installed by NEEB.

It was replaced with SP fusing, PVC cable and 13A sockets in the mid 60s.

Reply to
<me9
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: > Ring circuits and fused plugs were introduced in the UK : to save copper etc. in the post-WW2 rebuilding programme, : they have a number of disadvantages.

: Which are?

I take it that you have never come across the bolt being used as a 'fusible' link within the a Bullshi... sorry BS1363 plug that is feeding a device that draws < 3amp via a similar rated length of flex.

I take it that you have never come across the situation were an faulty appliance fails to blow the fusible wire within the Bullshit... sorry BS1363 plug but trips out the much more sensitive CB on the panel, taking out all other devices connected to that circuit (which in a house can be the entire power circuit.

The ONLY two advantage of ring circuits is installation cost and smaller size of fuse/CB panel.

Reply to
Jerry

Jerry,

I am happy for you that you are so certain. I suggest you practise 'thinking around the problem' a little more, and also clarifying your thinking. There are benefits and disadvantages to ring and spur circuits; and benefits and disadvantages to fuses and circuit breakers; and benefits and disadvantages to having fuses in plug-tops or at the consumer unit. Different choices will be better in different situations, and it is well worth understanding that. It is not the case that one method is unambiguously better than all the others in all situations.

To give an example: generally, domestic lighting circuits are not ring circuits, even though the circuit serving sockets frequently is. You might like to reflect on why that is. You may also like to reflect on why it is not uncommon for kitchens to have a ring circuit separate from the other circuits in a dwelling; and why immersion heaters are usually put on their own spur. And to start things off, what do you think the function of a plug-top fuse is?

Regards,

SId

Reply to
Sidney Endon-Lee

And this never happens with other fuses? Of course it does. Anyway, it's quite hard to use abol;t with many modern moulded plugs.

And no, I haven't come across it. Anyone who does that has probably done lots of other dangerous things too.

Pretty badly designed if it's the ONLY power circuit - our house has five rings.

Reply to
Bob Eager

Bollocks, it only need metal the same dia of the BS fuse, rather than having to dismantle a distribution board, take out a CB and replace even with a higher rated unit never mind a solid bridge.

: : And no, I haven't come across it. Anyone who does that has probably done : lots of other dangerous things too.

Your point being what, exactly?...

: : > I take it that you have never come across the situation were an faulty : > appliance fails to blow the fusible wire within the Bullshit... sorry : > BS1363 plug but trips out the much more sensitive CB on the panel, : > taking out all other devices connected to that circuit (which in a house : > can be the entire power circuit. : : Pretty badly designed if it's the ONLY power circuit - our house has five : rings. :

Only if you are being a pedantic fool and taking the meaning of the word "House" to me a multi floor dwelling rather than the more usual generic meaning of the word as a place were people live. Anyway, even if there was multiple ring circuits one faulty device will still take out all devices being powered from that circuit rather than just the one or two that would be on a radial circuit.

Reply to
Jerry

I was sufficiently intrigued to look that up, and you are completely correct - that standard domestic supply in Norway is IT, so the voltage from phase to neutral is about 133 V , and the voltage between phases is 230V. However, all new systems are now required to be TN.

I don't know if there are any standards in Norway for the phase to ground/earth voltage i.e. by how much neutral can float.

I guess that means all appliance and light switches need to be dual pole. It's a very different system to the UK.

Reply to
Sidney Endon-Lee

: > wrote: : >

: > : > : > Ring circuits and fused plugs were introduced in the UK : > : to save copper etc. in the post-WW2 rebuilding programme, : > : they have a number of disadvantages. : >

: > : Which are? : >

: > I take it that you have never come across the bolt being used as : > a 'fusible' link within the a Bullshi... sorry BS1363 plug that : > is feeding a device that draws < 3amp via a similar rated length : > of flex. : >

: > I take it that you have never come across the situation were an : > faulty appliance fails to blow the fusible wire within the : > Bullshit... sorry BS1363 plug but trips out the much more : > sensitive CB on the panel, taking out all other devices connected : > to that circuit (which in a house can be the entire power : > circuit. : >

: > The ONLY two advantage of ring circuits is installation cost and : > smaller size of fuse/CB panel. : > -- : > Regards, Jerry. : : Jerry, : : I am happy for you that you are so certain. I suggest you practise : 'thinking around the problem' a little more,

Who says I have not 'though through these problems', perhaps that IS why I have come to the conclusions I have...

and also clarifying your : thinking. There are benefits and disadvantages to ring and spur : circuits;

Err, spur circuits are supplied from ring circuits, thus they are one and the same, duh!

and benefits and disadvantages to fuses and circuit : breakers; and benefits and disadvantages to having fuses in plug-tops : or at the consumer unit. Different choices will be better in different : situations, and it is well worth understanding that. It is not the : case that one method is unambiguously better than all the others in : all situations. : : To give an example: generally, domestic lighting circuits are not ring : circuits, even though the circuit serving sockets frequently is.

Most of the domestic lighting circuits I've ever come across of based on looping in and out of ceiling (rose) fittings, thus one faulty fitting will trip all the lights on that circuit, hence why there will/should always be two lighting circuits (one usually for stair-well lighting) protected independently of each other BECAUSE the design failings of loop-in, loop-out circuits are recognised and accepted - one out, all out, so to speak!...

You : might like to reflect on why that is. You may also like to reflect on : why it is not uncommon for kitchens to have a ring circuit separate : from the other circuits in a dwelling; and why immersion heaters are : usually put on their own spur. And to start things off, what do you : think the function of a plug-top fuse is? :

Perhaps you should do the reflecting, WHY is it usual to install such circuits, perhaps if you actually thought through the actual issues then you would realise that you have made a very good argument against ring circuits!

Reply to
Jerry

No pedantry - you don't seem to understand at all.

Never mind - it'll ne OK when you finish Key Stage 2.

Reply to
Bob Eager

: > Only if you are being a pedantic fool and taking the meaning of the word : > "House" to me a multi floor dwelling rather than the more usual generic : > meaning of the word as a place were people live. Anyway, even if there : > was multiple ring circuits one faulty device will still take out all : > devices being powered from that circuit rather than just the one or two : > that would be on a radial circuit. : : No pedantry - you don't seem to understand at all.

Whhhoooossshhhh, unless you are makintg a very good case for radial circuits in small houses, flats and bungellows!

: : Never mind - it'll ne OK when you finish Key Stage 2.

Just because you are still at Key Stage 1, repeating, unquestioned, all your are being told parrot fashion, you think everyone else is...

Reply to
Jerry

I say, and it is self-evident from your answers so far.

Apologies, for 'spur', read 'radial'.

You didn't answer the question: perhaps you are confusing 'loop' and 'ring'.

I think you do need to take things a bit more slowly, and think deeply about your answers. Just because you do things in a certain way, possibly the way you were taught, doesn't necessarily make it the right way. You may, of course, be correct, but nothing you have said has convinced me you actually understand what you are doing.

Reply to
Sidney Endon-Lee

just because you have fished stage 2, don't assume that those of us with degrees in electrical engineering and a lifetime of dealing with electrical circuits haven't thought about it just as much as you have, and don't need to be patronised.

Reply to
The Natural Philosopher

The benefit of ring final circuits is...

1) Power is shared between two "legs" each of which must have a Corrected Current Carrying Capacity of 20A. Since most installs have FTE 2.5mm under capping/direct the two legs are individually often closer to a 27A rating so it is better than it appears. 2) CPC has 2 routes and twice the cross sectional area, which if into separate terminals is actually rather useful against "no CPC". 3) Prior to 17th where final circuit length was often limited by earth fault loop impedance having two CPC meant you could go substantially further than say a radial. 4) Ring final circuit could achieve a 32A final circuit using 2.5mm rather than more expensive 4.0mm which suffers the afliction of having only a 1.5mm CPC when TBH it could have had say 2.0mm.

The disadvantage of ring final circuits is...

1) Power draw may all be at one end of the ring, which is to say an imbalanced ring exists, for example 24A is supplied by one leg (above its 20A min rating) and only 8A in the other leg. It is here that ring finals have less of a leg to stand on. 2) Physical layout for a ring can actually be disadvantageous with solid floors, inaccessible ceiling voids etc, because you have twice as many cables as with a radial 3) 32A ring final circuit can tempt installers to fit just one such final circuit to a house, when it would be much wiser to have say 3 re upstairs, downstairs & kitchen.

Since I have solid floors, inaccessible ceiling voids, odd roof shapes and sloping ceilings, steel beams & chimney's everywhere etc, I much prefer 20A radials on a per room basis and 32A radial with 4mm in a kitchen. The original install had 32A radials on a per room basis including kitchen, however it is hard to justify 32A on a bedroom - that is over 3x 2kW fan heaters.

Lighting, loop-in does suffer from one lost supply, lose everything. You can use loop-in light switch which might be useful if future technologies require a neutral at the switch.

I designed a loop-in switch off a 2G accessible jn-box just below the ceiling, that way each room gets a supply to the switch (with neutral) and then switch to light fitting. If a room goes bad you can simply disconnect it quickly, test it, replace it - whilst other rooms are unaffected. Makes it easy to migrate from an old multi-junction box (19 for up & down lights) to a zero junction box system one-by-one with a MK Grid 2-module DP switch for "old lights" & "new lights" at the CU.

Lighting can be wired in a ring and often is industrially re 10A & even 16A lighting circuits, not so common domestically though. It provides some benefits like socket rings though. RCD reduce the need to get EFLI within 80% limit although personally I prefer that it is (TT rely on RCD critically for disconnect tho anyway).

Reply to
js.b1
[A very informative, long reply]

Thanks js.b1. That's the kind of reply I was hoping Jerry might come up with.

Sid

Reply to
Sidney Endon-Lee

No offence Jerry, but this is a load of ill thought out twaddle.

Being able to abuse a fuse in a plug is not a fault of ring circuit. The circuit in question could be a radial, and the circumstance would be no more desirable.

Again, this is nothing to do with circuit topology. As a general rule, overload related problems are more likely to blow the plug fuse, and hence result in "perfect" discrimination (i.e. the only device losing power is the faulty one). Fault (i.e. short circuit related) may occasionally trip a circuit breaker in the consumer unit. However again, this has nothing to do with circuit topology, the same could happen with a radial.

If you follow US practice for example where the only protection is at the origin of the circuit, then you can be sure to de-energise the whole circuit for all faults (either than or have to work out how to get at an internal appliance fuse).

In fact neither of these are true now. Installation cost, when installing from scratch is not significantly different. Also remember than in the UK we can have 32A radial circuits if required, so there is no particular advantage in reducing the number of ways in a consumer unit either.

It is important to realise that what started as a way of saving copper after the war, has been refined and improved over the years, to what we have now, which is a circuit that is very well suited to modern patterns of use. The ring circuit is also well suited to provision of power for "diverse" loads - i.e. large numbers of appliances can be provided for over a large floor area, and also higher power devices can be included in that mix without fear or overloading a circuit. Alternatively they also cope with applications where many high power appliances are used in proximity such as kitchens, where the ability to provision for 7.2kW of load without needing unmanageable cables sizes is a great advantage.

You have a circuit that behaves better under most of the common failure modes in circuit wiring (i.e. high resistance or broken conductors), and retains higher levels of protection under most of these failure modes.

For a full description see:

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circuits typically have lower earth fault loop impedances as well, result in quicker clearing of faults.

Reply to
John Rumm

For a type B MCB then voltage drop was the limiting factor for both rings and radials prior to the 17th ed. Under the 17th with a 5% volt drop allowed on sockets you can go even further.

But the word "further" is where the big difference between rings and radials matters.

I make good use of spurs for those far away sockets that would eat up lots of the maximum length of 2.5T&E if I was to include them on the ring.

Reply to
ARWadsworth

Although I suspect that Jerry has not realised it, his beef seems to be with fused plugs, since he has actually highlighted nothing of relevance to circuit topology. Plug fuses can be abused (as can rewireable fuses in consumer units), however in reality this much less of a problem that might be imagined. Most appliances are designed to be sold all over the world, and hence will usually have a flex that is capable of surviving faults with only 16A head end protection (as would be common in some countries), hence the fact that someone might substitute a 13A fuse in place of a 3A is not likely to be a problem with most appliances. There is the remaining issue that one could substitute a solid object for a fuse, but that does not appear to be something that happens regularly. Quite possibly because it is very rare for plug fuses to blow in the first place.

The absence of a plug fuse requires that the protective device at the head end of the circuit can clear not only overloads of the whole circuit, but also faults that may occur in light weight appliance flexes. This second requirement places significant restraints on the circuit as a whole, and drastically limits the total power supply capability. Hence the proliferation of inflexible[1] low current rated circuits you get in places like the US.

[1] Think about a kitchen / utility room with tumble drier, dish washer, and washing machine. That could represent 8kW of load - although it would be diverse - the chances of all three being in use at one time is relatively small, and the presence of thermostatic controls on the heaters will mitigate further. These could safely be power on one 32A ring circuit, but would probably require three 16A or 20A radials to do the same job.
Reply to
John Rumm

Oh, one other disadvantage (in theory) of 32A ring and indeed 32A radial is that a 2G socket is only capable of 19.5A continuously - somewhat less than 2x 13A fuse protection and somewhat less than the

32A fuse/circuit breaker.

I say in theory because running >19.5A continuouslly on a 2G socket is quite difficult. Even twin 2kW fan heaters are only 20A and are very likely to cycle on a thermostat. I guess in a warehouse it is possible, but that is not domestic. Tumbler dryer is a few hours at most, kettle minutes, toaster minutes. A commercial kitchen is one location perhaps.

Reply to
js.b1

One faulty device will just take out the fuse in the plug top.

Reply to
Brian D

What an elegantly crafted reply!

Reply to
The Wanderer

: >

: > Who says I have not 'though through these problems', perhaps that : > IS why I have come to the conclusions I have... : >

: I say, and it is self-evident from your answers so far.

Yes, that I have given the issues thought whilst all you appear to have done is read the building code/electrical regs - no doubt electricians in the US also blindly defend (their) *accepted* ways of "doing it"...

: >

: > and also clarifying your : > : thinking. There are benefits and disadvantages to ring and spur : > : circuits; : >

: > Err, spur circuits are supplied from ring circuits, thus they are : > one and the same, duh! : : Apologies, for 'spur', read 'radial'. : : >

: > and benefits and disadvantages to fuses and circuit : > : breakers; and benefits and disadvantages to having fuses in : > plug-tops : > : or at the consumer unit. Different choices will be better in : > different : > : situations, and it is well worth understanding that. It is not : > the : > : case that one method is unambiguously better than all the : > others in : > : all situations. : > : : > : To give an example: generally, domestic lighting circuits are : > not ring : > : circuits, even though the circuit serving sockets frequently : > is. : >

: > Most of the domestic lighting circuits I've ever come across of : > based on looping in and out of ceiling (rose) fittings, thus one : > faulty fitting will trip all the lights on that circuit, hence : > why there will/should always be two lighting circuits (one : > usually for stair-well lighting) protected independently of each : > other BECAUSE the design failings of loop-in, loop-out circuits : > are recognised and accepted - one out, all out, so to speak!... : >

: You didn't answer the question: perhaps you are confusing 'loop' and : 'ring'.

No, that is what you seem to be doing, or you simply do not understand the physical wiring schemes. There is very little

*schematic* difference in how a feed wires for lighting circuit loop in and out of the ceiling (rose) fitting and how the feed wires on a ring circuit loop in and out of sockets, the only differance is the lack of one set of conductors in the lighing circuit that would complete the 'ring' (and there is no techical reason why that conductor couldn't be pressent, other than added cost on instalation).

Ring Circuit; [CB1]==[SKT]==[SKT]==[SKT]==[SKT]==[CB1]

Lighting Circuit; [CB2]==[CRF]==[CRF]==[CRF]==[CRF]~~[CB2]

SKT = Socket CRF = Ceiling rose/light fitting

Spurs and switch drops are incidental [1] to how the *power* is delivered to the load, the missing conductor shown as ~~ is all that preventing the lighting circuit being a true 'ring' and if it was present the circuit would still work, still be protected and might even theoretically allow a smaller cross sectional conductor to be used.

[1] spurs are not always present whilst some light fittings / lighting instillations are devoid of individual switch drops

: >

: > You : > : might like to reflect on why that is. You may also like to : > reflect on : > : why it is not uncommon for kitchens to have a ring circuit : > separate : > : from the other circuits in a dwelling; and why immersion : > heaters are : > : usually put on their own spur. And to start things off, what do : > you : > : think the function of a plug-top fuse is? : > : : >

: > Perhaps you should do the reflecting, WHY is it usual to install : > such circuits, perhaps if you actually thought through the actual : > issues then you would realise that you have made a very good : > argument against ring circuits! : : I think you do need to take things a bit more slowly, and think deeply : about your answers. Just because you do things in a certain way, : possibly the way you were taught, doesn't necessarily make it the : right way. You may, of course, be correct, but nothing you have said : has convinced me you actually understand what you are doing.

Whilst nothing that you have said suggests that you actually understand anything other than what the regs say...

Reply to
Jerry

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