old imperial twin & earth

[MTI]

Hi all, thanks in advance. Please can anyone confirm (rather than give opinion ) if imperial T&E with integral earth was tinned aluminium or if indeed they made copper? off to check job out to confirm but it does indeed appear to be copper and not tinned from visual. By the way its grey smooth sheath and looks like pvc rather than soft black rubber. original 1970 wiring

 

[Guest55]

nearly always tinned copper
but there will have been a "cross over" period where clean copper was used prior to modern metric sized cables being introduced.
even the cable manufacturers wont be able to offer a "definative" yes / no answer.

as for aluminuim cable , youre unlikely to see it in any size less than 16mm.

 

[MTI]

cheers for the response. a very quick visual at CU looked like copper rather than tinned but I need to go back and do a PIR hopefully. I will use a blade to scrape the conductor and find out if its tinned but certainly didn't look like it. Agreed most old cable manufacturers are no longer around and if they are I will struggle to get a firm answer. The integral cpc was solid if I remember rightly and the L and N were stranded. solid concrete pad and flat roof with no access will be fun if im the bearer of bad news! Client wants new CU and earthing. Im sure I read somewhere not to use brass terminals with aluminium conductors. How would we stand with copper tinned?

 

[Guest55]

tinned copper is better than bare copper , it withstands damp better and improved metal fatigue , so no problems reconnecting the stuff.

aluminium is pants though and should be replaced.

 

[telectrix]

brass is fine with tinned copper, as brass is an alloy of copper ( with zinc, if irc ).

 

[MTI]

oh - think I have got my wires crossed (no pun intended!). so the tinning was copper and not aluminium with a copper coat? still, I either have straight copper or copper tinned copper - is that correct?

 

[Guest55]

bare copper or copper tinned with .... tin

 

[telectrix]

as biff said. plain copper or tinned copper. if it.s ali, it will be ali coloured and snap easily. cut a piece off and immerse in H2SO4. if it fizzes, it's ali.

 

[MTI]

right my daft moment is over - for a minute I thought I understood but now I do. tinned is tinned with tin! (red faced!) so I must have an installation which was done at the point of crossover between ali and copper as this is all copper with stranded L and N, solid earth (irc) and grey outer pvc-like sheath. cheers guys. all the best

 

[telectrix]

stranded copper cable was often tinned. this was back when things were made to a quality, not to a price, as when this solid rubbish came in.

 

[kingeri]

Out of interest, how many strands are there on the L and N? And how many on the CPC? 4mm T&E is easily confused with imperial, and I have almost made that mistake myself. My own house has older (circa 1978-1980) T&E in one wall of the kitchen on the socket circuits, when I first moved in I assumed it was imperial, it wasn't until I double checked (and even measured with Vernier callipers) that I fathomed that it was actually 4mm.

I believe the no. of strands forming the CPC is a big clue. Imperial 7/.029 and above had 3 or more stranded CPC. If the cable has a single stranded CPC it may be 4mm. Or bleeding copperclad carp, which will snap as soon as you fart near it.

 

[SJD]

stranded copper cable was often tinned. this was back when things were made to a quality, not to a price, as when this solid rubbish came in.

I've just rewired the lighting circuits a 1960-ish built house - the original cable was twin 1.0mm2 solid tinned copper in rubber (no earth) - and it was in beautiful condition, the rubber like new with like-new IR results. The rubber outer sheath had a light waxy coating as well. It was a shame to remove it, I felt the stuff I was installing was nowhere near as nice quality. Only done because there were quite a few unearthed metal fittings.

 

[MTI]

Out of interest, how many strands are there on the L and N? And how many on the CPC? 4mm T&E is easily confused with imperial, and I have almost made that mistake myself. My own house has older (circa 1978-1980) T&E in one wall of the kitchen on the socket circuits, when I first moved in I assumed it was imperial, it wasn't until I double checked (and even measured with Vernier callipers) that I fathomed that it was actually 4mm.

I believe the no. of strands forming the CPC is a big clue. Imperial 7/.029 and above had 3 or more stranded CPC. If the cable has a single stranded CPC it may be 4mm. Or bleeding copperclad carp, which will snap as soon as you fart near it.

Built 1970 give or take a year and is all original untouched barring probably more recently replaced accessories. Im pretty sure that the cpc was solid but could be wrong. ill have to confirm this. sorry didn't count cores on live conductors as was a v quick visual

 

[telectrix]

7/029... sockets etc., 7 strand. 3/029,,, lighting, 3 strand ( that's on L and N.)

 

[Engineer54]

If it had a solid strand CPC then you could well be looking at copper clad AL, they made that nasty stuff in stranded form from 1.5, 2.5, 4.0 6.0 10.0 and 16mm T&E . Ring circuits should have been wired in 4 mm on a max 30A OCPD and lighting in 1.5 on a max 5A OCPD.

Old Imperial would have been 7/029 with a 3/029 CPC, sometimes it could even be 7/036 also with a i think 3/029 or might have been a 3/036 CPC. Too long ago to remember!! lol!! So all stranded, if old Imperial cable.