Age of these electrics?

[JohnW2]

John ward will be proud of that. One socket circuit for the whole house.

That was certainly the case in the house in which I was living in 1965 (and remained true of that house for a good few years beyond that), and I suspect was almost the norm in those days. I actually suspect that we might have struggled a bit to find a total of 30A worth of load (even if everything were used simultaneously) in the house back then!

Kind Regards, John

 

[FrodoOne]

Just for the record .... a 'bare' earth wire ('no insulation at all') is totally normal for the usual house-wiring cables ('twin and earth'), even today. Modern twin and earth cable looks like this ....

Kind Regards, John

John.
While a 'bare' Earth wire is still used in TPS in the UK and in North America, at least in the UK there is a "requirement" that any such 'bare' Earth wire be sleeved.

Please see https://en.wikipedia.org/wiki/Electrical_wiring#Colour_code and note that in Australia/New Zealand it has been a requirement since 1966 that the Earth conductor in TPS be insulated, as for the Line and Neutral conductors. Initially the colour was Green but, since 1980 the colours have been Green/Yellow.
From that 'reference', it seems that insulating the Earth conductor also may be a requirement in several other countries (including other [ex?]EU countries.)

In addition, the Earth conductor in Australian/New Zealand cables has always been 'stranded', since at least 1945, if not before - when there wasn't any TPS.

Also, while TPS cable with solid conductors is still available up to 2.5 mm in AU/NZ, all TPS cables over 1 mm are available with 'stranded' conductors, at a slightly higher cost.
This additional cost is so small that any electrical contractor would need to be an idiot to use it (and some are), since stranded conductors are much easier to twist together and terminate, so that the time involved with using solid conductors much outweighs their cheapness.

I have handled the TPS cables that are available to you in the UK and to persons in North America.

You all have my sympathy concerning the difficulty of handling such cables as compared to the flexibility of AU/NZ stranded conductor TPS cables.

https://en.wikipedia.org/wiki/File:Tps-3core.png shows a photo of pre-1980 NZ 2.5 mm T&E TPS Cable with insulated stranded conductors.

Of course, in North America most of the terminals on switches and socket outlets are designed to have a single solid conductor screwed down in a clockwise direction, so that stranded conductors cannot be used with most such (cheap) domestic equipment.
At least the UK is in a better position concerning the possibility of using stranded conductors.

 

[JohnW2]

John. While a 'bare' Earth wire is still used in TPS in the UK and in North America, at least in the UK there is a "requirement" that any such 'bare' Earth wire be sleeved.

Firstly, for the benefit of anyone who may wonder what you are talking about, I have virtually never heard PVC insulated and sheathed cables being described as "TPS" cables in the UK.

The is no UK requirement for the CPC ('earth') conductor of fixed wiring cables to be insulated - if there were, then virtually every electrical installation in the UK which used multi-core cables would be in violation of that requirement!! The requirement for an insulated CPC/'earth' only applies to flexible cables (e.g. 'appliance cords').

Please see https://en.wikipedia.org/wiki/Electrical_wiring#Colour_code

.... if you are referring to the bit about core colours, that is just plain wrong. Whoever wrote it seems to think that, when we changed to 'harmonised' identification colours for fixed wiring (on 31 March 2004), the UK also acquired a requirement for the CPC of fixed wiring to be insulated. That is NOT true. In other words, the final column the first row of this is wrong....

I think there are probably pros and cons of having bare CPCs in fixed wiring. One advantage is that it increases the probability that something penetrating a cable and coming in contact with a live conductor will also come in contact with the CPC, thereby hopefully causing a protective device to operate.

... This additional cost is so small that any electrical contractor would need to be an idiot to use it (and some are), since stranded conductors are much easier to twist together and terminate, so that the time involved with using solid conductors much outweighs their cheapness.

Solid conductors do not needed to be 'twisted' at all, and twisting together of two of them is regarded as bad practice.

I have handled the TPS cables that are available to you in the UK and to persons in North America. You all have my sympathy concerning the difficulty of handling such cables as compared to the flexibility of AU/NZ stranded conductor TPS cables.

I've never handled it, but I suspect that your cables are more flexible 'overall', leading to a requirement for more ('time consuming') cable support?

Kind Regards, John

 

[wrightsonm]

If the wiring is from 1965, it may be worthwhile looking for evidence of green residue on the cable ends, in the back boxes, or on the back of the fittings. PVC Cables from 1960-1970 ish had an issue where the plasticzer leaks out of the cable making it brittle. I certainly found exactly this on a couple of cables in my home dated 1965.

 

[AndyPRK]

Note the little b in the picture which states

Cables may have an uninsulated PE which is sleeved with the appropriate identifying colours at both ends, especially in the UK.

 

[JohnW2]

Note the little b in the picture which states. Cables may have an uninsulated PE which is sleeved with the appropriate identifying colours at both ends, especially in the UK.

So it does - FrodoOne obviously missed that, too. Mind you, I think it's still a bit misleading, since that "may have" belies the fact that such is actually the norm in the UK.

It also makes one wonder why that column in the two 'rows' differ. The second row (which also has a 'b' next to the G/Y-insulated conductor also depicts a bare CPC, with a description saying "no insulation (previously). Sleeved at the ends.", which seems redundant (and would be equally applicable {without the "previously"} in the first row)!

Whatever, I presume that all of us in the UK can agree that 'the norm' remains for the CPC in multi-core fixed-wiring cables to be bare, usually with G/Y sleeving at the ends. I don't even know whether one can get 'fixed wiring multi-core cables' (i.e. not flex) in the UK which has an insulated CPC, can one?

Kind Regards, John

 

[FrodoOne]

Firstly, for the benefit of anyone who may wonder what you are talking about, I have virtually never heard PVC insulated and sheathed cables being described as "TPS" cables in the UK.

The is no UK requirement for the CPC ('earth') conductor of fixed wiring cables to be insulated - if there were, then virtually every electrical installation in the UK which used multi-core cables would be in violation of that requirement!! The requirement for an insulated CPC/'earth' only applies to flexible cables (e.g. 'appliance cords').
.... if you are referring to the bit about core colours, that is just plain wrong. Whoever wrote it seems to think that, when we changed to 'harmonised' identification colours for fixed wiring (on 31 March 2004), the UK also acquired a requirement for the CPC of fixed wiring to be insulated. That is NOT true. In other words, the final column the first row of this is wrong....

View attachment 163255

I think there are probably pros and cons of having bare CPCs in fixed wiring. One advantage is that it increases the probability that something penetrating a cable and coming in contact with a live conductor will also come in contact with the CPC, thereby hopefully causing a protective device to operate.

Solid conductors do not needed to be 'twisted' at all, and twisting together of two of them is regarded as bad practice.
I've never handled it, but I suspect that your cables are more flexible 'overall', leading to a requirement for more ('time consuming') cable support?

Kind Regards, John

Oops.
We may have a language problem here. Normal Australian nomenclature is TPS but the North Americans call this cable NM (Non Metallic [insulation] in their weird way) or by the Trade Name of "Romex" - which has some paper "insulation" in its construction and so cannot be used outdoors.

Yes "There is no UK requirement for the CPC ('earth') conductor of fixed wiring cables to be insulated " - which was exactly the burthen of my comment.

You and others should all note that everyone has the ability to "correct" any reference in Wikipedia as you see fit so to do.
(If you do so you run the risk that someone else may "correct" you, and so it goes.)

You stated "Solid conductors do not needed (sic) to be 'twisted' at all, and twisting together of two of them is regarded as bad practice."
Really? How could you combine two conductors in the rear of one socket outlet without twisting them together? (Please explain.)

Your statement of "I think there are probably pros and cons of having bare CPCs in fixed wiring. One advantage is that it increases the probability that something penetrating a cable and coming in contact with a live conductor will also come in contact with the CPC, thereby hopefully causing a protective device to operate." is quite 'problematic'.
You seem to consider that no insulation on the Earth conductor within a cable is better than some insulation on that conductor because inadvertent penetration by a metallic object is somewhat more likely to produce a fault condition.

You also wrote "Whatever, I presume that all of us in the UK can agree that 'the norm' remains for the CPC in multi-core fixed-wiring cables to be bare, usually with G/Y sleeving at the ends. I don't even know whether one can get 'fixed wiring multi-core cables' (i.e. not flex) in the UK which has an insulated CPC, can one?"

Yes. I know that that is so.
However, there are other countries where an insulated CPC is the "Norm" and is required in these countries. Hence, insulated sleeving at the ends is not required and the additional cost is minimal.

Another point that I mentioned is that the North Americans do not require any such end sleeving, which can cause them some problems with their relatively primitive electrical connections.

You stated "I suspect that your cables are more flexible 'overall', leading to a requirement for more ('time consuming') cable support?"
The only time when "cable support" (presumably, via "cable clips" et al) would be significant would be where it could be seen. Within a building structure such spacing would be dictated by the spacing of the studs, joists etc.
Australian regulations indicate a spacing of not more than 350 mm between such cable clips.

At this point, I am reminded of a reference where an Electrical Inspector inspected a shed on a farmer's property and commented that the "wiring" was probably not done by an "electrician".
"How so?" asked the farmer.
The inspector replied. "Because it is too neat."

 

[JohnW2]

Oops. We may have a language problem here. Normal Australian nomenclature is TPS but the North Americans call this cable NM (Non Metallic [insulation] in their weird way) ...

Yes, a language problem. As I said, the term "TPS" is not really used in the UK. If we want a descriptive term, we call it "insulated and sheathed", but the type of cable we're mainly talking about is usually called "twin and earth" (or "3-core and earth", where appropriate), it being essentially implicit that that means 'flat cable' with PVC insulation and PVC sheathing.

Yes "There is no UK requirement for the CPC ('earth') conductor of fixed wiring cables to be insulated " - which was exactly the burthen of my comment.

That's not quite how I read your comment. As mentioned below, sleeving at the terminations is as much for identification as for insulation.

You stated "Solid conductors do not needed (sic) to be 'twisted' at all, and twisting together of two of them is regarded as bad practice." Really? How could you combine two conductors in the rear of one socket outlet without twisting them together? (Please explain.)

Put them both into the same terminal, without twisting them, and grip them with the terminal screw or cage. It can get a bit more iffy with more than two conductors. However, if one twists solid conductors, they can weaken or even fracture.

You seem to consider that no insulation on the Earth conductor within a cable is better than some insulation on that conductor because inadvertent penetration by a metallic object is somewhat more likely to produce a fault condition.

Yes, I mentioned that as one of the potential 'pros' of having a bare CPC.

However, there are other countries where an insulated CPC is the "Norm" and is required in these countries.

Indeed so - but I was talking about the UK. This is, after all, the "Electrics UK" forum

Hence, insulated sleeving at the ends is not required and the additional cost is minimal. Another point that I mentioned is that the North Americans do not require any such end sleeving, which can cause them some problems with their relatively primitive electrical connections.

Although generally regarded as 'good practice', I'm not at all sure that there is any UK regulation requiring the ends of a bare CPC to be sleeved. As above, sleeving, when used, is as much for identification as insulation.

Kind Regards, John

 

[EFLImpudence]

Answering both of you while quoting Frodo:

Yes "There is no UK requirement for the CPC ('earth') conductor of fixed wiring cables to be insulated " - which was exactly the burthen of my comment.

I think there is a further issue of nomenclature.
John seems to be implying that 'fixed wiring' is another name for 'flat t & e'.

Surely 'fixed wiring' is simply cabling that one has 'fixed'; it could be any kind of cable.

You stated "Solid conductors do not needed (sic) to be 'twisted' at all, and twisting together of two of them is regarded as bad practice."
Really? How could you combine two conductors in the rear of one socket outlet without twisting them together? (Please explain.)

I think we are talking about solid cores - so quite simply.
If the terminal is small enough that the screw grips both conductors, then mission accomplished; if not then the conductor can be bent back on itself to, in effect, make four conductors in the terminal.

Your statement of "I think there are probably pros and cons of having bare CPCs in fixed wiring. One advantage is that it increases the probability that something penetrating a cable and coming in contact with a live conductor will also come in contact with the CPC, thereby hopefully causing a protective device to operate." is quite 'problematic'.
You seem to consider that no insulation on the Earth conductor within a cable is better than some insulation on that conductor because inadvertent penetration by a metallic object is somewhat more likely to produce a fault condition.

Yes, is that not beneficial?

You also wrote "Whatever, I presume that all of us in the UK can agree that 'the norm' remains for the CPC in multi-core fixed-wiring cables to be bare, usually with G/Y sleeving at the ends. I don't even know whether one can get 'fixed wiring multi-core cables' (i.e. not flex) in the UK which has an insulated CPC, can one?"

Again, if I 'fix' cables with an insulated CPCs then one can obviously 'get' 'fixed wiring multi-core cables'.

Has anyone gone to a shop and asked for 'fixed wiring cable' please.

Yes. I know that that is so.
However, there are other countries where an insulated CPC is the "Norm" and is required in these countries. Hence, insulated sleeving at the ends is not required and the additional cost is minimal.

I have never figured out why sleeving is necessary. Surely a wire intended to operate the OPD should it come into contact with a loose live conductor would be better not sleeved - like the metal back box.

 

[AndyPRK]

I'm not sure why we would what to compare things to america.

Doesn't Ireland use TPS ?

 

[JohnW2]

I think there is a further issue of nomenclature. John seems to be implying that 'fixed wiring' is another name for 'flat t & e'. Surely 'fixed wiring' is simply cabling that one has 'fixed'; it could be any kind of cable.

It could - and, yes, I'm suggesting that, in practice, 'fixed wiring' (by which I really mean 'wiring of an installation', even if it is not literally 'fixed') nearly always means 'flat T+E'.

One could, as you imply, use, say, 'flexible cable' to wire an installation, but I'm not at all sure that one would then have any choice, because I'm not aware of any 'flexible cable' with a bare CPC. As for wiring which is not 'fixed' (part of an installation) (e.g. appliance cables), I'm not sure what regulations would apply (not BS7671) but I somehow doubt that, even if it were available, a flexible cable with a bare CPC would be acceptable, would it?

I have never figured out why sleeving is necessary. Surely a wire intended to operate the OPD should it come into contact with a loose live conductor would be better not sleeved - like the metal back box.

As I said, although it seems to be regarded as bad practice not to sleeve bar CPCs within accessories etc., I'm far from convinced that any regulation actually requires it. Whilst I certainly agree that, in many situations (e.g. within JBs), it probably achieves nothing, I think the perceived problem is not 'loose live conductors' but rather that when one pushes an accessory into a backbox, a bare CPC could bend and come into contact with a (non-loose) live part.

Kind Regards, John

 

[JohnW2]

Doesn't Ireland use TPS ?

The phrase/abbreviation, you mean? If so, I haven't got a clue.

It simply means "Thermoplastic Sheathed Cable", so theoretically covers the great majority of 'everyday' cables, of all types which have a PVC (or other thermoplastic) outer sheath.

Kind Regards, John

 

[EFLImpudence]

It could - and, yes, I'm suggesting that, in practice, 'fixed wiring' (by which I really mean 'wiring of an installation', even if it is not literally 'fixed') nearly always means 'flat T+E'.

...but that's the point; it doesn't, does it?
You have said yourself "nearly always" therefore...

SWA, Control cables, Fire alarm cables, Bell wire etc.

 

[AndyPRK]

I mean

insulated cpc in fixed wiring

 

[JohnW2]

I mean ... insulated cpc in fixed wiring

Fair enough - and I don't know the answer to that (in Ireland), either. However, as I said, if taken literally, "TPS" merely refers to the material of the outer sheath, saying nothing about inner insulation (or its absence).

It could be that, in countries which talk about "TPS", it is taken to imply that all the cores also have thermoplastic insulation - but if that is the case, it's really just a 'convention', since "TPS" does not mean that!

This discussion seems to be about all sorts of countries other than the UK - I'm not convinced that it's happening the the correct forum

Kind Regards, John