4mm² Cable

[securespark]

The thread about 4 milli T&E radials got me pondering about the cpc size.

Like 2.5, did 4 milli ever have a 1 milli cpc?

If so, like 2.5/ 1.0, would an acceptable solution be swapping any such circuits on 3036's onto breakers?

 

[JohnW2]

Like 2.5, did 4 milli ever have a 1 milli cpc?

I don't know (someone probably will!) but I would very much doubt it - to have a CPC with 40% of that of the live conductors is one thing, but 25% would seem 'a step too far'.

If so, like 2.5/ 1.0, would an acceptable solution be swapping any such circuits on 3036's onto breakers?

In view of the above, this question is probably moot. However, although I haven't done the sums, it wouldn't surprise me to find that, adiabatically speaking, a 1mm² CPC was adequate for a 30/32A circuit, maybe even with a 3036 - but one would have to do the sums to find out. Whether such a cable (if it existed) would be adequate in terms of disconnection times would obviously depend on various factors (e.g. cable length and Ze) as well as the nature of the OPD.

However, as I said, I rather doubt that such a cable ever existed. Are you asking because you think you've found some?

Kind Regards, John

 

[securespark]

Not sure. Can't make up my mind...

 

[333rocky333]

Would if it existed be in the tables of old regs books, like the 15th edition

 

[333rocky333]

Not sure. Can't make up my mind...

Evident by all the posts in GD when you buy something

 

[JohnW2]

Would if it existed be in the tables of old regs books, like the 15th edition

Would it? I don't think the current regs give any information on the size of CPs in T+E cables, do they?

Kind Regards, John

 

[333rocky333]

I honestly dont remember, how detailed they were, or are now, but I know SS has some old regs books.

 

[rsgaz]

like the 15th edition

Go back a bit more! Table D.2, 14th.......

Old Imperial "7/.029" Twin and Earth

So 7/036 cable (4.52mm²) had a 0.97mm² CPC when it was metal sheathed and a 2.90mm² CPC for rubber or PVC.

 

[333rocky333]

Go back a bit more! Table D.2, 14th.......

Old Imperial "7/.029" Twin and Earth

He mentioned 4mm
I assumed he did not mean imperial equivalents
Though as I thought it was more detailed back then

 

[securespark]

I have looked in the 14th. If the cable was imperial, it could only be either 1/.044 or 3/.029 or 3/.036 because they have single stranded cpc's like the PVC cable I have been given to identify.

But it can't be any of those, as the live conductors have 7 strands.
And if the live conductors have 7 strands, the cpc ought to have 3 or 7.

So I assume it is metric.
Comparing the cpc of this cable with 1.0mm² conductors, they seem identical (though I don't have accurate measuring equipment).

Certainly, 1.5mm² is thicker.
I am wondering if it is a early stranded 2.5mm² T&E with 1.0mm² cpc.

Either that or it is 4 milli with a 1 milli cpc....?
But I doubt that now.

 

[333rocky333]

i usually gauge unknown cable by using a red or blue crimp

 

[securespark]

Yeah, thought of that, but I think I chucked 'em out.
Can't find any.