Pls help identifying T&E cable size.

It's probably 7/.044 which was rated at 36 A. 4.5mm is the metric equivalent.

charles wrote in news: snipped-for-privacy@charleshope.demon.co.uk:

Many thanks for that. Now for the dumb question! What is the max wattage of electric shower I can use this for? Probably none, right?

Al

do the maths - 8kW.

I'd say probably 7/0.29. That was the old equivalent of 2.5mm ring cable. But 7/0.44" is also possible - you'd need to measure a strand more carefully. The 0.29" etc is the diameter IIRC.

charles wrote in news: snipped-for-privacy@charleshope.demon.co.uk:

Thanks; that's encouraging. I'm not challenging your math, but the TLC cable calculator below says says I'd need 10mm cable for an 8kw shower. (same for a 7kw one). Perhaps they factor in some overkill to cover themselves and/or perhaps make more profit? The length of my cable run is

Calculator I used is here:

TIA

Al

You first need to make *absolutely* sure what the cable you have is. The

Measure a strand with a digital caliper.

Erm 0.029" I think you mean.

The problem is the OP said about 1mm and 0.029" is under 3/4mm

Accurate measurements and simple calculation is needed.

The only 7/ 029 I've worked with was TRS which in that era invariably was black. O/P iirc is saying a white sheath.

Andrew

I've come across plenty of PVC 7/029 in the past, but only grey.

I don't have any 7/029 clips left (I do have 1/029 though), but 2.5mm clips are only 10mm across. That's why I suspected 7/044. The stranmg diameter also seem to agree with .044

No, there was PVC in Imperial sizes. I re-wired my house in in 1964 using PVC.

As the earth wire is single strand, it must be 7/029. Rated at 20 amps, equivalent to 2.5mm these days.

Commonly used for wiring sockets, usually a ring main

If you go from the overall size, and compare with the figures in the last column of the table here:

That suggests something around the 6mm^2 mark, or its imperial equal.

While 7/.029" could be treated as roughly equal to 2.5mm^2 these days (it actually a bit more), its inappropriate to describe it as "20 amps". The rating will depend on the installation method.

The 14th edition quotes a "clipped direct" rating of 25A, which seems rather conservative given that's less than the 27A quoted for 2.5mm^2 in the same circumstances these days.

But the 14th Edition would assume rewireable fuse, but the current edition assumes MCB and has an optional derating for rewireable fuse?

Owain

Indeed, there is a de-rating factor 0.725 allocated for re-wireable fuses now. Hence my comment about 25A rating being conservative in a modern setting - the 2.9mm^2 that 7/.029 is approximately in modern money, would probably have a clipped direct rating of around 34A with MCB protection.

John Rumm wrote in news: snipped-for-privacy@brightview.co.uk:

I measured another piece of this cable. I am relying on a tape-measure, not a micrometer; the OD appears to be to be possibly 7mm x 13.5mm, which is close to the '6.8 x 13.1' stated as the OD of 6mm^ cable. However, would the insulation thicknesses be the same in the 1970s/1980s as it is today?

Somewhere buried in my house, I have an imperial micrometer. If I can somehow manage to find it, I'll be able to measure the exact thicknesses of the copper wires.

Anyway, assuming it is 6mm^, and I use a circuit breaker at the end of my

I have some vague recollection of hearing someone say it was frowned-upon to connect two or three shorter lengths of this stuff together, when feeding a high-wattage appliance. It that a hard-and-fast rule, or is it okay to have a couple or more joints using those round, hard plastic 30A junction boxes?

Thanks to all for the help. Al

I did, sorry.

I'd rather an accurate measurement than 'about'

And the overall diameter of the conductor was said to be about 3mm, which says 7/0.029 to me.

But I don't have any handy to check.

The only way is to measure a single stand *accurately*.