cable sizes

[nospam]

Hello,

Can I ask a daft question: when a cable is described as being 25mm, what does this mean because it certainly is not an inch thick!?

Thanks.

[Martin Pentreath]

2.5mm is a more likely dimension. It means (as far as I'm aware) the cross-sectional area of the conductors (at least the live and neutral ones - the earth in twin-and-earth cable is usually a bit less beefy than the other two).

Here's a useful conversion table that I cut and pasted from somewhere some time ago:

CSA (CPC) Strands Overall mm^2 No./dia. mm approx.

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

1.0 (1.0) 1/1.13 4.5 x 8.2 1.5 (1.0) 1/1.38 4.7 x 8.2 2.5 (1.5) 1/1.78* 5.3 x 9.9 4.0 (1.5) 7/0.85 6.1 x 11.4 6.0 (2.5) 7/1.04 6.8 x 13.1 10 (4.0) 7/1.35 8.4 x 16.8 16 (6.0) 7/1.71 9.6 x 19.5

• or 7/0.67

[Ben Blaukopf]

It's 25 mm2 cross sectional area. (i.e. about 4mm thick plus a wodge of insulation).

Ben

[Peter Andrews]

Normally refers to the cross section area.

Peter

[Osprey]

You won't or shouldn't see that ... what you would see is 'xx mm2' where the xx is the cross sectional area of the cable.

So 2.5mm2 (typical ring final circuits) is a cable where each of the current carrying cores is 2.5mm2 in cross sectional area.

25mm2 is not a standard domestic size.

[The Natural Philosopher]

Sure you don't mean 2.5mm sq, which is cross sectional area of the conductors..of a typical 30A mains ring cable.

[Bob Eager]

Cross sectional area (of one of the conductors).

[Bob Eager]

Except for meter tails! You can even buy it (at a price) in B&Q.

[Andy Wade]

[snip]

From here actually:

it can be found without the original formatting messed up :-)

[Joe Lee]

25mm2 is the standard size for domestic 'meter tails'.

Joe Lee

[Dave Fawthrop]

| [e-mail] wrote: |> Hello, |>

|> Can I ask a daft question: when a cable is described as being 25mm, |> what does this mean because it certainly is not an inch thick!? |>

|> Thanks. | | |2.5mm is a more likely dimension. It means (as far as I'm aware) the |cross-sectional area of the conductors (at least the live and neutral |ones - the earth in twin-and-earth cable is usually a bit less beefy |than the other two). | |Here's a useful conversion table that I cut and pasted from somewhere |some time ago: | |CSA (CPC) Strands Overall |mm^2 No./dia. mm approx. |--------- ------- ---------- |1.0 (1.0) 1/1.13 4.5 x 8.2 |1.5 (1.0) 1/1.38 4.7 x 8.2 |2.5 (1.5) 1/1.78* 5.3 x 9.9 |4.0 (1.5) 7/0.85 6.1 x 11.4 |6.0 (2.5) 7/1.04 6.8 x 13.1 |10 (4.0) 7/1.35 8.4 x 16.8 |16 (6.0) 7/1.71 9.6 x 19.5 |* or 7/0.67

I suppose 7/029 and 3/036 (number of strands/diameter of 1/1000 ins) are long forgotten except by really *old* engineers like me :-(

[Dave Plowman (News)]

Just remember their replacements are 2.5 and 1.5mm² ;-)

[Martin Pentreath]

Ah yes, that looks much better.

As a tribute to its usefulness I'd cut and pasted it into my palm computer where I keep important bits of DIY trivia for reference when needed. Unfortunately the palm is not as good as Google when it comes to retaining formatting, but it's easier to refer to when you're rooting around in the cellar trying to work out what's what!

Cheers!

Martin

[Owain]

Us young 'uns with big junkboxes have vaguely heard of them too :-)

Owain