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).