Pls help identifying T&E cable size.

[Dave Plowman (News)]

7/0.029 came in both grey and white PVC too. If it was older rubber, then yes, black.

[Dave Plowman (News)]

7/0.029 TW&E was a lot wider than 2.5mm. At first glance it looked more like the next size up in metric.

[Dave Plowman (News)]

Simply not the way to measure it. Imperial cable external dimensions were much larger than the equivalent metric.

Imperial lighting TW&E 3/0.029 was approx the same outside size as 2.5mm TW&E.

It's also far more likely to find 7/0.029 cable lying around. Larger stuff in those days only likely used for an electric cooker - showers were rare if they even existed.

[John Rumm]

For PVC they are likely to be similar - but the overall cable sheath size was not standardised then or now - so its not a cast iron guarantee. You will need to get a calliper on the conductors to be sure.

Yup, that's what you need to be certain.

Yup, its commonly used for cookers, and used to be used for showers when they were more modest in power than many modern ones.

You will need RCD protection now (17th edition rules) as well.

To check any cable for adequacy, run through the procedure described here:

With high current circuits, you have most risk of heating at the termination points. So the more you have, the more "risk" if you like. However if you do the job correctly and make the terminations tightly (or better still crimp or solder them), there there is no problem joining cables.

You will have difficulty getting 2 x 6mm^2 into many junction boxes, so look for one of the high current ones designed for the application.

Something like:

may be a better bet.

[Robert]

If you have some digital kitchen scales, you could always cut off a fixed length of the 7 strands , weigh it (the copper) and work out the crossectional area. About 20cms should give enough accuracy to differentiate 2.5, 4 and 6mm^2 cores ( assuming 1g accuracy on scales). Copper is 8.96 g cm^-3

[Brian Reay]

My understanding is you should use the 'new colours' for new installations. If you have the installation checked, and being a shower you should, then you may have a problem.

I'm not trying to be officious, just helping you avoid potential issues.

We had a new kitchen installed several years back which required some electrical work, including 'spurs' (new colours) etc. for the induction hob, double oven and the like, and a new consumer unit. As the existing wiring has the 'old colours' a there is a note warning that the installation has 'mixed colours' and the whole installation was checked under the dreaded 'part P' as part of the contract.

[ARW]

Correct.

If this is indeed a new installation then one wonders why the OP is asking the question and is not just fitting 10mm T&E and fitting a higher rated shower.

I suspect that some of the cable is already in place and the OP wants to reuse it.

[Brian Reay]

Another point, don't skimp on the shower itself.

We've had cheaper, 7kW or so, showers in the past than they were never really that good. They worked but you couldn't get a 'hot' shower, and they were prone to cutting out due to thinking they were too hot. They were the better end of the 7kW range.

We now have a Mira Advance ATL and can't fault it*. It is 9kW and you can have it as hot as you are likely to want, with a good flow rate. They aren't cheap but, in my view, worth the money.

*Well, I saw we can't fault it, my wife doesn't like the blue LEDs but she has a 'thing' about blue LEDs.

There may be other makes of course, I'm just going by our experience.

[John Rumm]

There is no requirement to replace an existing cable though it its adequate for the job.

In the real world its really a non issue IME. Conveyancing solicitors etc long since lost interest in electrics.

If worried, say you are happy for the purchaser to have inspection done at their expense, under the understanding that there will be no price reduction or remedial action taken regardless of the outcome! Its a sellers market at the moment ;-)

[charles]

I understand that if you mark the ends with the new colours then it is permissable to use cable to the old spec.

[AL_n]

Robert wrote in news:cul7urFs2q1U1 @mid.individual.net:

Thanks for the tip. I cut off 200mm off one of the 7-strand wires, and after stripping, it weighs 11g (to the nearest g, I guess since it doesn't register decimals). That was using an electronic letter scale. I checked the reading on a second electronic letter scale, and got the same reading.

Unfortunately math is one of my worst subjects and I can't get my head around the formula to calculate what I need to know. Can anyone tell me what the cable is now?

Al

[AL_n]

John Rumm wrote in news:qNKdnfS- [e-mail]:

I must remember that one; I like it!

Al

[AL_n]

"ARW" wrote in news:mm3s4o$6m8$1@dont- email.me:

Good deduction! Actually, the whole house is wired in matching white- covered, red+black inner cables, so at least it'll all be cosistent. :)

Al

[BruceB]

Provided the cable is sleeved with the correct colour at its terminations, then it meets current regulations (514.3.2).

[Andy Burns]

Seems equivalent to 6mm^2

[AL_n]

Andy Burns wrote in news: [e-mail]:

Many thanks!

Al

[AL_n]

Brian Reay wrote in news:mm3s84$6m0$ [e-mail]:

Thanks for the tip. I'll be sure to keep the guarantee, whatever I get. Then if it gives me any gyp I can take it back. I feel sure that a 7.5Kw will be adequate, as I always prefer a modest water flow from a shower. That's partly because the shower will be over a bath with a shower curtain, and I don't like any ovespray getting onto the floor etc.

Al

[Tough Guy no. 1265]

Voltage drop for 240V is negligible. It's how well insulated the run is that matters, not the length.

[Tough Guy no. 1265]

The only problem with having mixed colours is when you have 3 phase in the building. Black can be live or neutral. And I saw the consequences - 40 broken computers and a fair bit of a stink when they got 2 phase given to them. Fixed them all by replacing the capacitors though, which the insurance company didn't think of.

[Charles Hope]

The voltage drop will be the same for any voltage - it's dependant on current. Insulation doesn't affect voltage drop.