Talk:Cables

If someone can remember the date that flex colours changed to their current form, there is a <date> place holder waiting to be filled in.

--John Rumm 01:17, 23 May 2007 (BST)

Google got me nowhere. I thought it was 70 or maybe 71. NT 23:31, 23 May 2007 (BST)

Woa there! NT

That table you pulled you cut'n'pasted, I had not finished writing it yet! ;-)

Puzzled

I'm puzzled by the reason for removal of:

"Any design must ensure the maximum voltage drop allowed between source and point of use is not exceeded when at full load. This is usually defined as 4% of the nominal supply voltage (about 9.2V at 230V AC)"

Surely this is key info for v drop calcs?

I think your eyes may be deceiving you - the text is still there right at the start of the table --John Rumm 16:54, 19 August 2007 (BST)

I'm also puzzled why the voltage drop table has been renamed 'swa,' and why it is now a subsection of 'imperial t&e'

it is in a section of its own, not a subsection of either type. The comment on PVC and MICC etc however does not seem quite right since most SWA is not PVC these days, and the table lists two sets of figures anyway - not just 70 degree C ones.

I'm also wondering why the addition of the sentence saying the Vdrop table applies to swa. AFAIK copper is used in all other types of mains cables that any diyer will ever work with, and has been for over 20 years. And afaik the max temps of swa & t&e are the same, so changing resistivity with temperature wont make any difference either. Thus the Vdrop table will apply to all 70C rated pvc insulated cables NT 22:48, 5 June 2007 (BST)

Usually they will be close or very similar. However the thermal capacity of different cable constructions can change the linearity of the resistivity gradient, so it is possible for some combinations of conductor size and number of cores to get slightly different answers. --John Rumm 16:54, 19 August 2007 (BST)

Rename

I propose renaming this article to "Cables - mains" so that a separate "Cables - Low Voltage" can be created. Would make it easier on the reader than one giant article with both subjects mixed into it. NT 12:37, 19 August 2007 (BST)

Do you mean LV as in 12V AC lighting etc, or are you thinking more of CAT5 etc? For the former the cable (i.e. solid core) used tends to be the same as for mains. Perhaps Cable - power and cable - <some other name> would be more inline (bearing in mind that 240V is technically "LV"). --John Rumm 16:54, 19 August 2007 (BST)

By LV I mean below 50v, and all cables that are used for LV tasks. Yes this would include T&E.

> bearing in mind that 240V is technically "LV"

Its one point of view of course. Personally I prefer the view accepted by most electronics experts.

Anyway, I think splitting the 2 would make life a fair bit simpler. NT 22:22, 19 August 2007 (BST)

I have no objection to splitting, just would avoid using the nomenclature of LV since that is fairly well entrenched in the wiring regs etc as less than 500V. Perhaps "Cable - Power Distribution", and "Cable - Control and Signal"

--John Rumm 22:52, 19 August 2007 (BST)

Yes, I agree with non-controversial names, people get confused otherwise.

Table

This could be worked into the article as and when. From uk.d-i-y.

Here are the two tables combined into one, together with some new ratings from the draft 17th edition:

CSA (CPC) Ratings in amperes Strands Overall square mm A B C D+ E+ No./dia. mm approx.

---

---- -- -- -- ---- ------- ----------

1 (1) 11.5 12 16 13 10.5 1/1.13 4.5 x 8.2 1.5 (1) 14.5 15 20 16 13 1/1.38 4.7 x 8.2 2.5 (1.5) 20 21 27 21 17 1/1.78* 5.3 x 9.9 4 (1.5) 26 27 37 27 22 7/0.85 6.1 x 11.4 6 (2.5) 32 35 47 34 27 7/1.04 6.8 x 13.1 10 (4) 44 47 64 45 36 7/1.35 8.4 x 16.8 16 (6) 57 63 85 57 46 7/1.71 9.6 x 19.5

• 7/0.67 also available (but rare)

Key to current rating columns:

A - in conduit in insulated wall (ref. method 6) B - directly in insulated wall (ref. method 15) C - clipped direct (ref. method 1)

Ratings (BS 7671 Table 4D5A) apply for ambient temperature of 30 deg.C and conductor temperature of 70 deg.C

+ New ratings from draft 17th edition:

D - above plasterboard ceiling covered by thermal insulation,

    insulation thickness <100 mm 

E - as D but with insulation thickness >100 mm

(Technically these are not yet in force and should be regarded as provisional.)

All the usual derating factors apply (see appendix 4 of BS 7671 or appendix 6 of the OSG).

DONE --John Rumm 04:06, 5 September 2007 (BST)

Terminology

Line or live conductor?

Live or Phase - "Line" is a bit US centric. ("Phase" is the technically most correct since a neutral is really a "live" conductor as well as the phase if one is being accurate. However the colloquial use of "live" is so common it is hard to avoid). --John Rumm 05:47, 17 September 2007 (BST)

Also the phrase 'Low Smoke and Halon' seems to have gotten left out. NT 21:48, 12 September 2007 (BST)

Yup, I noticed that as well. I could not muster the enthusiasm to change it at the time, but I might now... ;-) --John Rumm 05:47, 17 September 2007 (BST)

LV!

Dear Friends, I think the term LV (low voltage) specifically refers to 230V or 240V, anything below that is Extra low voltage (elv)!

Vincent Mukiibi

Hi Vincent, in the uk wiring regs any voltage at or below 500V is actually termed LV. ELV (or more commonly) SELV is indeed the correct term for 12V lighting installs. Hence the comments half way up this page about what to call a new article on non mains wiring.

--John Rumm 16:53, 18 September 2007 (BST)

Just so you know where it all comes from....

In the wider world of electronics mains isnt generally called low voltage, plus in common colloquial use ditto, hence the situation. In electronics mains voltage is not usually described as 'low' and often called high in the worldwide arena. The terminology adopted by the 16th is far from universally used or accepted.

I understand where the colloquial use comes from, and also accept that the wiring regs usage is rather non intuitive (unless you routinely work on 135kV power distributions systems I suppose). My only concern was that since we are talking about mains wiring it helps if we are consistent in terminology not only between our own articles, but also with the regs and OSG since that makes it easier to understand the official docs.

How about 'Cables, Lower Voltage'? Seems to cover it all, and 'Cables' could stay as it is. NT 17:56, 18 September 2007 (BST)

I would be inclined to have one for "Cables, power distribution", and "Cables, Data and Signal". SELV will often user power distribution cables anyway (or flex). Perhaps a separate article "12V Power System Wiring", to cover some of the special gottchas of 12V lighting wiring (high current, voltage drop, transmission line effects etc).

--212.56.101.160 19:03, 18 September 2007 (BST)

T&E Outdoors

This is what happens to unpainted T&E after 20 years in direct sun. The damage is only a fraction of a mm deep.

Maybe the pic could be useful somewhere, just dont know where! NT 15:45, 23 July 2008 (BST)

How well does it bend? Have you done an insulation resistance measurement on it?

(to be fair, T&E outside will normally last a decent length of time as long as it is not physically abused. However different makes and colours do perform differently). --John Rumm 04:06, 24 July 2008 (BST)

Hi John

Bending is as new, the damage is only a fraction of a mm deep. I didn't insulation test it, it was still in service, but I can't see the superficial degradation having an effect on insulation value for another century or so. NT 19:04, 24 July 2008 (BST)

Earthshield

from ukdiy... (maybe someone else knows more about these than me)

I looked into those (Earthshield, flexishield, XL-Shield etc). IIRC, they have some constraints, such as Prospective fault current being <6kA (or might have been 5kA) and use of Type B breakers and limits on the maximum circuit rating (I don't think they can manage a 40A circuit). I think it was to do with ensuring that a fault to the foil screen would knock out the breaker before blowing a hold in itself. They're not cheap either.

Although FP200 has a similar construction and is ubiquitous, it doesn't hold a BS8436 rating (pity).

OTOH, seemed a neat solution for lighting in particular where there may be many drops.

Cheers

Tim

That table

Any particular reason for adding colour code info straight after the table that contains the exact same info? ;-)

--John Rumm 17:06, 13 August 2009 (BST)

Its not the exact same info :) The colour translations are a little different, the cable types are different too. NT 19:59, 13 August 2009 (BST)

OK, looking closer I see what you mean - they are different. Wrong mind you, but different! ;-)

2 core was red and black 3 core was red yellow blue 4 core was red yellow blue and black 5 core was red yellow blue black and green/yellow

These become:

2 core brown and blue 3 core brown black grey 4 core brown black grey and blue 5 core brown black grey blue, and green/yellow.

See [1] for confirmation.