Replacing old twin cables

[gardener1214388]

I want to replace old twin cables;

One twin cable has a Thick Red pvc outer sleeve inside that is a smaller thinner Red pvc coated single copper core wire, the other wire is a smaller pvc green coated single copper core wire

One twin cable consists of a Thick Black pvc outer sleeve with a thin green stripe on the outside covering a smaller black pvc single copper core wire the other wire is a smaller pvc green with thin black stripe coated copper core wire.

Question: Would you replace these; for lighting with 1.5mm flat grey twin and earth. I prefer 1.5mm for lighting; the 1mm looks a bit flimsy.

Question: I cannot find any twin cable that would do the job properly, is twin lighting cable available; if so who supplies it.

I look forward to your input.

 

[diyer56]

Like this?

http://www.cef.co.uk/catalogue/categories/10496-6241y-flat-single-core-earth

 

[Risteard]

I prefer 1.5mm for lighting; the 1mm looks a bit flimsy.

It isn't. 1mm^2 cable will likely be ideal for your application. Why overspecify?

 

[gardener1214388]

Like this?

http://www.cef.co.uk/catalogue/categories/10496-6241y-flat-single-core-earth[/QUOTE]

Many Thanks for the prompt reply; marvellous;

Question; Would you suggest; as I have 50 meters of 1.5mm grey flat twin and earth for lighting; that I use this instead and cut the appropriate wire back as required.

 

[gardener1214388]

I prefer 1.5mm for lighting; the 1mm looks a bit flimsy.

It isn't. 1mm^2 cable will likely be ideal for your application. Why overspecify?

Many Thanks; but dare I say it; I've always used 1.5mm belt and braces; 1mm just looks too thin and flimsy; some regs go up and some go down and I am not convinced all of the time, but then that's me.

 

[gardener1214388]

I prefer 1.5mm for lighting; the 1mm looks a bit flimsy.

It isn't. 1mm^2 cable will likely be ideal for your application. Why overspecify?

Q - Do you know what the maximum permitted single run (ms) is for this cable for lighting.

 

[Risteard]

I prefer 1.5mm for lighting; the 1mm looks a bit flimsy.

It isn't. 1mm^2 cable will likely be ideal for your application. Why overspecify?

Q - Do you know what the maximum permitted single run (ms) is for this cable for lighting.

It is likely to be limited by volt drop. If you take the guidance for lighting this is generally taken as 3% (though that is not actually a requirement - ensuring proper functioning of equipment is). So depending on the design current, and bearing in mind that it will not be evenly distributed (the load will decrease the further from the distribution board you go) then it can be worked out. But for a domestic premises it really isn't going to be an issue.

 

[JohnW2]

I prefer 1.5mm for lighting; the 1mm looks a bit flimsy.

It isn't. 1mm^2 cable will likely be ideal for your application. Why overspecify?

Q - Do you know what the maximum permitted single run (ms) is for this cable for lighting.

It is likely to be limited by volt drop. If you take the guidance for lighting this is generally taken as 3% (though that is not actually a requirement - ensuring proper functioning of equipment is). So depending on the design current, and bearing in mind that it will not be evenly distributed (the load will decrease the further from the distribution board you go) then it can be worked out. But for a domestic premises it really isn't going to be an issue.

As you say, it's very easy to work out. With 1mm² cable, the maximum permissible length to remain within a 3% voltage drop (assuming 230V) with 6A flowing (very unlikely these days - that's is about 1380W of lighting) is about 26 metres.

As you also rightly point out, despite what a lot of people seem to think, that 3% limit is not a rule, but merely a 'deemed-to-satisfy' provision. Any amount of voltage drop is permitted by the regs provided only that 'safe' (not even 'proper') functioning of equipment is preserved.

From the point of view of current-carrying capacity (as opposed to voltage drop), any length of 1mm² cable is obviously more than adequate for a 6A lighting circuit.

Kind Regards, John

 

[securespark]

Are these cables feeding lighting at the moment?

Might you be better off replacing them with conventional T & E?

 

[Risteard]

As you say, it's very easy to work out. With 1mm² cable, the maximum permissible length to remain within a 3% voltage drop (assuming 230V) with 6A flowing (very unlikely these days - that's is about 1380W of lighting) is about 26 metres.

And of course that assumes that the full load is present at the extremity of the cable run, which of course it isn't.

 

[JohnW2]

Might you be better off replacing them with conventional T & E?

My understanding is that that is what the OP is proposing and asking about.

Kind Regards, John

 

[securespark]

Like this?

http://www.cef.co.uk/catalogue/categories/10496-6241y-flat-single-core-earth[/QUOTE]

Many Thanks for the prompt reply; marvellous;

Question; Would you suggest; as I have 50 meters of 1.5mm grey flat twin and earth for lighting; that I use this instead and cut the appropriate wire back as required.

 

[JohnW2]

As you say, it's very easy to work out. With 1mm² cable, the maximum permissible length to remain within a 3% voltage drop (assuming 230V) with 6A flowing (very unlikely these days - that's is about 1380W of lighting) is about 26 metres.

And of course that assumes that the full load is present at the extremity of the cable run, which of course it isn't.

Indeed it almost always won't be - although, I suppose, one might theoretically approach that situation if a circuit from a distant CU served a few lights close to the end of the cable.

Particularly with today's very low lighting loads, if T&E smaller than 1mm² were available (and allowed), we'd probably be using it (with appropriate OPDs - but still maybe 6A!) for lighting circuits!

Kind Regards, John ²