Thickness of main flex

[Santa Al]

For the purposes of this posting ...

(a) ... keep the current carrying capacity of a three-core mains flex
constant.

(b) ... ignore any specialist mains flex such flex designed for
permanent outdoor use.

(c) ... do not ignore the possibility that there may be a greater or
lesser number of filaments (depending on what is permitted) in the
multi-stranded cores.

----

(Q1) Is there a defined range of dimensions which the insulation
protecting each of the three cores must adhere to?

(Q2) Is the size of outer protective sheath (often PVC) subject to
some regulations which dtermine a max and a min diameter?

I am in the UK.

----

In the end, I would like to know how (in percentage terms) the
maximum variation is final outer diameter I am likely to encounter
when buying flex only by specifying its current carrying capacity.

Thanks!
Al

 

[Tim Dunne]

"Santa Al" <no@no-email.com> wrote in message
news:Xns989F6FD4DE45F71F3M4@127.0.0.1

In the end, I would like to know how (in percentage terms) the
maximum variation is final outer diameter I am likely to encounter
when buying flex only by specifying its current carrying capacity.

www.doyourownhomeworkyoubozo.com

Tim


--
Sent from Birmingham, UK timdunne at blueyonder.co.uk
'God's electrician sparked up the heavens once again, heading northbound
on the 7:10. And the lord said let there be commuters...' - Thea Gilmore
Look, mum, an anorak on a bike! Check out www.nervouscyclist.org

 

[Santa Al]

On 20 Dec 2006, Tim Dunne <Bit_Bucket@Blueyonder.co.uk> wrote:

"Santa Al" <no@no-email.com> wrote in message
news:Xns989F6FD4DE45F71F3M4@127.0.0.1

In the end, I would like to know how (in percentage terms) the
maximum variation is final outer diameter I am likely to encounter
when buying flex only by specifying its current carrying capacity.

www.doyourownhomeworkyoubozo.com

Tim

Hi Tim, that's the nicest thing anyone has said to me all day!

---

I think you will find that the specs governing cables and similar
items are not freely available on the Net.

They are often chargeable documents (at hugley inflated prices)
available from the standards' institutions concerned.

This question is about just a portion of a standard so no one is
going to buy one or more of the standards just because you post your
strange goading stuff.

I know Xmas can be a stressfull time but why do you want to show us
all how badly you are coping?

OTOH if you have the answer then please let me know.

 

[Adam Aglionby]

Santa Al wrote:

For the purposes of this posting ...

(a) ... keep the current carrying capacity of a three-core mains flex
constant.

(b) ... ignore any specialist mains flex such flex designed for
permanent outdoor use.

(c) ... do not ignore the possibility that there may be a greater or
lesser number of filaments (depending on what is permitted) in the
multi-stranded cores.

----

(Q1) Is there a defined range of dimensions which the insulation
protecting each of the three cores must adhere to?

Ain`t no totally defined current carrying standards either, got a reel
sitting here thats going back mainly because its the wrong colour, its
catalogue page said 13A 3 core flex, conductor area is 1.25mm, usually
wouldn`t pull 13A along much thinner than 1.5mm or 2.5mm at any
distance. Current handling and length are related.

(Q2) Is the size of outer protective sheath (often PVC) subject to
some regulations which dtermine a max and a min diameter?

PVC, toughened rubber, silicone etc. Best bet would guess would be
taking an average of O.D.s of appropriate cables from somewhere like
R.S

Adam

I am in the UK.

----

In the end, I would like to know how (in percentage terms) the
maximum variation is final outer diameter I am likely to encounter
when buying flex only by specifying its current carrying capacity.

Thanks!
Al

 

[Andrew Gabriel]

In article <1166645699.248399.190140@t46g2000cwa.googlegroups.com>,
"Adam Aglionby" <ledlight@gmail.com> writes:

Ain`t no totally defined current carrying standards either, got a reel
sitting here thats going back mainly because its the wrong colour, its
catalogue page said 13A 3 core flex, conductor area is 1.25mm, usually
wouldn`t pull 13A along much thinner than 1.5mm or 2.5mm at any
distance. Current handling and length are related.

The PAT test guidelines are good for this. For a 13A extension cable:
1.25mm˛ max length 12m
1.5mm˛ max length 15m
2.5mm˛ max length 25m (but won't fit nicely into 13A plugs).
(spot the pattern -- these are easy to remember

These max lengths are to ensure earth fault loop impedance is
still acceptable at the far end of the cable. Other alternatives
are to use an RCD at the start of the cable, or to reduce the
fuse value below 13A, in inverse proportion to the excess length
above the maximum values above.

--
Andrew Gabriel

 

[Lostgallifreyan]

andrew@cucumber.demon.co.uk (Andrew Gabriel) wrote in
news:4589bbb8$0$762$5a6aecb4@news.aaisp.net.uk:

In article <1166645699.248399.190140@t46g2000cwa.googlegroups.com>,
"Adam Aglionby" <ledlight@gmail.com> writes:

Ain`t no totally defined current carrying standards either, got a reel
sitting here thats going back mainly because its the wrong colour, its
catalogue page said 13A 3 core flex, conductor area is 1.25mm, usually
wouldn`t pull 13A along much thinner than 1.5mm or 2.5mm at any
distance. Current handling and length are related.

The PAT test guidelines are good for this. For a 13A extension cable:
1.25mm˛ max length 12m
1.5mm˛ max length 15m
2.5mm˛ max length 25m (but won't fit nicely into 13A plugs).
(spot the pattern -- these are easy to remember

These max lengths are to ensure earth fault loop impedance is
still acceptable at the far end of the cable. Other alternatives
are to use an RCD at the start of the cable, or to reduce the
fuse value below 13A, in inverse proportion to the excess length
above the maximum values above.

Nice guide. I question that bit about the fuse though, mains voltage is
usually constant enough that it can't drive extra current to overcome the
extra resistance. Even if it did, the heat dissipated per unit length is
the same along the whole length, so there's no danger unless the cable is
coiled up tightly enough to allow enough heat buildup to melt the
insulation.

It makes sense to choose the fuse value to suit the appliance's maximum
draw (which will be partly based on knowing what the cable can supply), but
it doesn't make sense to base the fuse value on the cable directly except
where the current can rise, unless you take into account the effect of heat
buildup, maybe.