For comparison -- A piece of American 12-2 w/ground Romex and a piece of British 6242Y 2.5 sq. mm. T&E (with reduced-size ground wire):


Larger image

The "Twin & Earth" cable looks closer to UF cable IMO.

T & E cable would make good switch legs here in the US, no re-identifing the white. LOL

Could you legally use the British "romex" in the USA? If it's listed or approved by the revalent British agnecy, is that good enough, or does the NEC require that the agency be an American outfit?

I'd love to have some of that wire for DC circuits and switch loops! I have a feeling that the reduced GEC would be an issue. Is it available with a full-sized earth?

Yes, it looks like UF. Are all y'all (that's plural for "y'all") aware that the Klein NM strippers also work very well on UF?

These guys: http://www.kleintools.com/cutterstrippers/index.html

I'm amazed that they both have solid earths. I don't think we have ever used solid earths in Australia. Stranded is much less likely to snap off at terminations. Stranded conductors are pretty much the norm here for everything except domestic light circuits. Much easier to work with and less likely to break.
If you use single insulated wires in conduit runs are they solid too? That's when you really notice how much easier stranded is to use.



[This message has been edited by briselec (edited 04-15-2006).]

We use solid up to 10 AWG (40 amp capacity if that helps on the size)

All our NM 10 AWG and smaller is solid.

Snapping is not a problem and I like to work with solid.

Cables 'push' a lot farther when solid than when stranded.

The T&E's conductors appears to be slightly smaller in diameter than the #12s. But still larger than #14. Like a #13

Is the ampacity between 15-20 Amps?

Yes but pulling is a lot easier with stranded.

What I'd like to know from you guys over the pond is why do you have all that "paper" stuffed into your cables? I have seen it many times and wondered.

In answer to the ampacity of 2.5mm T&E, it is rated at around 20Amps. The actual current depends on the conditions it is installed under e.g. in thermal insulation or in free air.

Is it really?

Most of our job specs require solid for sizes smaller than 8 AWG so I am pretty much used to it.

In some ways I find solid easer as it does not turn into a giant mess when you have to pull a loop out of a pull point.

But it is clearly a personal choice.

Bob

[This message has been edited by iwire (edited 04-16-2006).]

I don't know, we have outdoor/underground cable called UF that has the same construction as the 'T&E'

The paper makes for easy stripping so I hope it stays.


Yeah we have the same issues so giving a definitive rating is difficult without knowing how the cable will be used.

Unfortunately, these traditional colors have just been phased out (no longer permitted under our Regs. for new work since 4/1/06). The new version is this:




No. Only the smallest 1.0 sq. mm size (used primarily for lighting circuits) has an earth the same size as the other conductors.


2.5 sq. mm is just a tiny fraction smaller than #13.

Click here for AWG/metric conversion chart

Having now worked with both Romex and T&E, I can safely say that the Romex is easier to strip.


As far as British T&E is concerned, the 2.5 pictured above plus the two smaller sizes are always solid. 4 sq. mm (about #11 AWG) and upward is stranded. (Although with the reduced earth, the 4 sq. mm cable actually has a solid 2.5 earth conductor.)

However, stranded was used for smaller sizes of T&E before we changed to metric sizes around 1970. For example, here's a piece of 7/.029 from the 1960s:



The old designations specified the number of strands and the diameter of each strand, thus 7/.029 is 7 strands of 0.029" each. That gives a conductor CSA of 0.0045 sq. in., equivalent to approx 2.9 sq. mm or somewhere between #12 and #13 AWG.

Here are the comparative sizes of all three cables for reference. Top to bottom: 2.5 sq. mm T&E, 7/.029" T&E, #12 Romex:


Note the reduced earth still on the old cable: Only 3 strands but each of larger diameter than those in the live conductors.

Here's another old stranded cable, 3/.029 which works out to 0.002 sq. in. CSA, approx. 1.3 sq. mm or #16 AWG. This is a 3-core without earth, which is all I could find in my scrap box:


Under the old system, only the smallest T&E of 1/.044 wasn't stranded (near enough 1 sq. mm or a fraction smaller then #17 AWG).

P.S. Yes, the strands on the old cable were tinned. They changed to bare copper with the move to metric-sized cable about 1970.




[This message has been edited by pauluk (edited 04-16-2006).]

Paul, if you have any of that red and black cable laying around, send it to me. Even a sample to show my guys would be cool, but I'd love to have some in useable lengths.

If shipping, which I'd cover, isn't prohibitive, I'm serious. Otherwise, I'm just kidding.

We also had 1/.064

I remember on a project having to resort to using a hunk of 4 x 2 and a sledgehammer trying to straighten out some very big solid core pyros. Give me stranded any day.

Bob,
A lot of the specs in this area call for stranded and if they do permit solid it is often only up to #12. If they speced solid #10, I would give them two prices. A price ~20% higher for the additional labor requried to use solid 10 in conduit and the lower price using stranded.
Don

Sample lengths are about all I have left of the "old" red/black T&E I'm afraid. Details coming to you by e-mail Larry.......


That's an interesting one. When did Australia switch to metric-sized cables?

The old British cable sizes pre-metric can be seen listed here, along with current ratings and other data (taken from IEE Regs. 1966 edition):
https://www.electrical-contractor.net/pc/IEE1966_T3.JPG

Don I had already been thinking of you in this thread, I know you had said you guys stay away from solid.

We do not, that I know of price it differently.

Its all in what the labor force is used to working with.

If we priced dwelling units with EMT the price would go up as our guys are not used to that, for guys in your area it's just another day.

For us solid does not slow us down, but we use more than the code required size boxes and are used to the solid.

I just started a job Monday that is 100% EMT that is very unusual for us and it is a nice change from the typical cable work we do. With an average of four guys we got in a little over 5000' since Tuesday.

Its all 3/4" and 1" for branch circuits in a large retail store. All 20 amps circuits are speced 10 AWG but they did not specify solid or stranded. As it is up to me we will be using stranded.

I read an article in a trade mag that said solid provides a slight energy savings over the life of an electrical system. I have always figured that is why the engineers around here have a thing for solid.

Bob

Around the mid to late 70s.
Very conveniently we also changed to using insulated earths about the same time so if you find an installed T&E with a bare earth wire in it you know it's imperial.

WOULD YOU BELEIVE THE PAPER IN ROMEX IS TO PREVENT FLASH FIRE FROM OCCURING

Larry - twin and earth with UK old colours is available on Ebay in 100m reels depending on how much you're willing to spend on getting some!
http://cgi.ebay.co.uk/1-5-twin-and-...9228QQcategoryZ57215QQrdZ1QQcmdZViewItem

Bob,
How? The amount of copper is the same for solid and stranded and given the skin effect, yes a very small effect at 60 hz, the impedance of stranded should be slightly less.
If you haven't tried stranded how do you know?
Don

Come to Canada then. We have red/black 12/2 NMB (called NMD-90 here, no paper though) up the wazoo. It is mostly used for electric heating, but I have seen it used for switchloops. It comes in red sheathing instead of yellow or white.


[This message has been edited by classicsat (edited 04-17-2006).]

Don't know, I also did not say I believed it, only that I read it a few years ago in one of the trade magazines.


I never said we don't use stranded.

All our cable (smaller than 8) is solid, many (most) of the jobs are specified solid.

As I said the EMT job I am doing now the wire type is not specified so it is up to me. I will choose stranded, although the supply house already sent out solid 10 Green.

Bob

Bob,
It is about 15% more expensive than solid, so don't get me in trouble with your estimator if you don't make up the additional material costs with a reduction in the labor costs.
Don

The paper in NM cable is there to help protect the conductors from abrasion and keep the shape of the cable, sort of like Juting did years ago...do you remember the juting?

German NYM and Austrian YM (basically the same stuff) have a soft rubber filler. Quality cables with rubber filler are real easy to strip. Only nick the sheath all the way around, bend the cable and pull off the sheath. Love it!

Strande isn't really used for fixed domestic wiring here (many people even believe it's illegal). I really prefer solid for anything up to 10mm2!

At a friend's place somebody wired the bathroom with 2.5mm2 stranded. He did an extreme hack job, only connecting half of the strands (it's a miracle the place never burnt down!). When we tried to reterminate it correctly, using ferrules I hated it! Most of all getting the wires into the choc blocks was crazy work! We ended up repulling everything using 2.5mm2 solid.

Although British 2.5 sq. mm "T&E" has solid conductors, when it comes to singles for use in conduit, 2.5 is available in both solid and stranded.