Double Insulated Singles

[topcop999]

I am a qualified spark. I have encountered a scenario and something in my head tells me that it is a no no. I cant find the regulation documented anywhere. I am sure I read it last year and the lacking availability of double insulated 1.5mm singes would support my thoughts.

This is a change to an existing installation whereby there are limitations on how much damage can be caused to rewire it to my liking. The scenario is a 3 way grid switch, the common line is supplied by a 1.5mm flat twin and earth sheathed cable. The black conductor is used as a switched line return for a nearby lamp. The question is, can I run another 2 x single double insulated line conductors in the already installed metal (earthed, buried in wall) conduit, in order to feed two separate nearby lamps, which have already have neutral supplied from the same circuit. Basically the question is can you run a single double insulated line conductor without a CPC adjacent to it? Obviously each lighting point, switch and accessory does have a CPC. We obviously used to do this regularly on the old style lighting systems with the two core strappers? Any comments or advice greatly appreciated.........

 

[KINKY]

I would say you can.

EDIT:
Thinking about it, cant see any reson at all why not.

 

[UNG]

I don't see any reason why you can't do what you are proposing, I use double insulated singles quite alot for similar jobs

6181Y (double insulated single core) and 6241Y (double insulated single core with CPC) has never been easy to get hold of as most wholesalers will tell you there is no call for it. Recently I was in the stores of a wholesaler I use and they had a reasonable stock of it on the shelf which surprised me

 

[topcop999]

Thanks UNG... It seems as though I have mis-read something as the general consensus so far is that it can be done.

I managed to get some from Newey & Eyre, who I found had a fair stock, to my surprise as most other outlets did not stock it.

I was holding off doing the job until I had clarified this,

Thanks

 

[Andyfm]

There was a little known reg in the 16th that stated that all single live conductors must be incorported into a cable with an earth - or something similar - but I don`t know if it was excluded from the 17th

 

[DJ wilki]

All 230v cables need to have a cpc, this is in the 17th. Best place for them is either cef or newheys.

 

[nickblake]

All 230v cables need to have a cpc, this is in the 17th. Best place for them is either cef or newheys.

where , what about lawn mowers drills etc

i have enquired with elecsa's technical regarding the use of double insulated singles cables and there is no problem using them

 

[sparkylad]

TopCop. -Nothing wrong with what you are proposing--standard wiring practice as far as I can see .

 

[topcop999]

Thanks all for your replies. I feel the general trend is that this is allowable. It is obviously one of those grey areas which is why I queried it in the first place.

 

[Risteard]

I don't see it as a grey area at all. All points in the wiring must have a cpc but there is nothing wrong with using singles. Nothing to say that all cables must incorporate cpc (otherwise they wouldn't manufacture such cable surely).

 

[UNG]

I don't see it as a grey area at all. All points in the wiring must have a cpc but there is nothing wrong with using singles. Nothing to say that all cables must incorporate cpc (otherwise they wouldn't manufacture such cable surely).

This is my thinking as well

 

[topcop999]

Good point Risteard, I have a NAPIT assessment due next week so will run it past him too.. Think its just been my mind working overtime!

 

[Andyfm]

There wasn`t british standards approval on Single and earth cable IIRC, so should not be used( though i dont know if this has changed)

 

[Benny_Boy]

Reg 543.2.7

Use the earthed metal conduit as CPC and earth the accessory to the enclosure with a separate CPC.

job done no?

 

[topcop999]

Not that simple Benny Boy, maybe my explanation didn't make it clear. The earthed conduit only runs within the wall, then the single double insulated will run on its own in the ceiling void to the lamp ceiling rose, approximately 4 metres away. The ceiling rose already has a line, neutral and earth supply, however the conduit was of insufficient width to accommodate the usual twin and earth switch wire. As I mentioned, the householder does not wish to disturb their beautiful wall.

 

[Benny_Boy]

Not that simple Benny Boy, maybe my explanation didn't make it clear. The earthed conduit only runs within the wall, then the single double insulated will run on its own in the ceiling void to the lamp ceiling rose, approximately 4 metres away. The ceiling rose already has a line, neutral and earth supply, however the conduit was of insufficient width to accommodate the usual twin and earth switch wire. As I mentioned, the householder does not wish to disturb their beautiful wall.

Ah I see.

 

[Risteard]

I presume by "double insulated" you mean insulated and sheathed.

 

[Pinto Baz]

I presume by "double insulated" you mean insulated and sheathed.

Thanks Risteard, I've been going purple trying not to say that!

In a public building where there may at some time be a hearing aid induction loop fitted single cables can cause inteference if not run with their neutral or opposing flow live (return switch etc) Other than that I can't think of anythink that makes single sheathed cables any different to twin.

 

[Pinto Baz]

Just thought of something that might have prompted your original question. If you do run a seperate earth cable, that should be run adjacent to the cable that it protects. It's just for traceability

 

[topcop999]

Thanks Pinto Baz.... I think that was along the lines that I had read, at some point in my obscure studies! I don't recall what I had read stating why it should be run adjacent, but you have clarified that. Any idea what reg this is under?

Thanks