I want to use multicore cabel for domestic instalation ,but i dont
have 2,5 mm cable.
But I have only 4 core by 1.5 mm. Can I join the cores 2 by 2 to reach
a beter ampacity?
And what MCB for this combination? The cable marker is - H05 V V - F

In article .com,
"p" writes:
I want to use multicore cabel for domestic instalation ,but i dont
have 2,5 mm cable.
But I have only 4 core by 1.5 mm. Can I join the cores 2 by 2 to reach
a beter ampacity?

Not viable.

This would invoke the "conductors in parallel" part of
the regs, and it just isn't viable in the scenario you
describe as an alternative to buying the correct 2.5mm
cable in the first place.

--
Andrew Gabriel

But 1.5 mm by two is a 3mm. Isn"t this combination supposed to carry a
better load than a 2.5mm.

Thank you!

On 16 Nov 2005 00:05:36 -0800, "p" wrote:

But 1.5 mm by two is a 3mm. Isn"t this combination supposed to carry a
better load than a 2.5mm.

Thank you!

Yes, but if you're determined to breach the wiring regulations why
bother asking in the first place ?

Andy

I'm asking because I dont have experience in that kind of work. I juist
want to know if it is possible to use it and how much load it is
carryng. And whot ampacity of MCB to use for this.
I juist want to ack someone with better experience than me.

"" I want to use multicore cabel for domestic instalation ,but i dont
have 2,5 mm cable.
But I have only 4 core by 1.5 mm. Can I join the cores 2 by 2 to reach
a beter ampacity?
And what MCB for this combination? The cable marker is - H05 V V - F ""

Thank you!

p wrote:
But 1.5 mm by two is a 3mm.
No. The measurement is the diameter of the core, but the current
carrying capacity is related to the cross-sectional area.

Two by 1.5mm has an area of 3.53 mm2

One by 2.5 has an area of 4.91 mm2.

Isn't this combination supposed to carry a
better load than a 2.5mm.

No. You would need three 1.5mm cores to carry more than a 2.5mm core -
and that assumes you can get all three cores to carry their fair share
of current. That is a pretty poor assumption in the long run (which is
almost certainly why parallel conductors are essentially banned in the
regs).

In article .com,
says...

p wrote:
But 1.5 mm by two is a 3mm.
No. The measurement is the diameter of the core, but the current
carrying capacity is related to the cross-sectional area.


I think you're wrong. The measurement _is_ the cross-sectional area i.e
1.5mm^2

In an earlier contribution to this discussion,
AJB wrote:

In article .com,
says...

p wrote:
But 1.5 mm by two is a 3mm.
No. The measurement is the diameter of the core, but the current
carrying capacity is related to the cross-sectional area.


I think you're wrong. The measurement _is_ the cross-sectional area
i.e
1.5mm^2

That is correct. A 2.5mm cable actually means a cross-section of 2.5
*square* mm - *not* a diameter of 2.5mm - so 2 x 1.5 *does* equal 3!

[One might be forgiven for believing that a 2.5(sq)mm cable was 2.5mm in
diameter because it's relatively close to that - at about 1.8mm. However,
the difference is very obvious with larger cables. For example, a 10 (sq)mm
cable has a diameter of only about 3.6mm.]
--
Cheers,
Set Square
______
Please reply to newsgroup. Reply address is invalid.

If doubling a cable diameter in this fashion is not Kosha then how come
a Ring Main is legal ?

chris.

wrote:
If doubling a cable diameter in this fashion is not Kosha then how come
a Ring Main is legal ?

30A/32A ring circuit in 2.5mm^2 cable (or 1.5mm^2 MICC) is explicitly
excluded from Conductors in Parallel regs.

--
Andrew Gabriel

wrote:
If doubling a cable diameter in this fashion is not Kosha then how come
a Ring Main is legal ?

chris.

Well, mainly because I was wrong :-)

In an earlier contribution to this discussion,
Andrew Gabriel wrote:

In article .com,
"p" writes:
I want to use multicore cabel for domestic instalation ,but i dont
have 2,5 mm cable.
But I have only 4 core by 1.5 mm. Can I join the cores 2 by 2 to
reach a beter ampacity?

Not viable.

This would invoke the "conductors in parallel" part of
the regs, and it just isn't viable in the scenario you
describe as an alternative to buying the correct 2.5mm
cable in the first place.

As a matter of interest, what's the rationale for banning this? It
presumably would *work* - is it just that it may cause confusion to anyone
working on it in future?
--
Cheers,
Set Square
______
Please reply to newsgroup. Reply address is invalid.

I imagine one issue is current sharing between the conductors. Whilst
the current share may be close to 50/50 when installed, any slightly
loose connection or corrosion of one conductor could cause one
conductor to end up carrying most of the current. not good.

wrote:
I imagine one issue is current sharing between the conductors. Whilst
the current share may be close to 50/50 when installed, any slightly
loose connection or corrosion of one conductor could cause one
conductor to end up carrying most of the current. not good.

Yes, that's one issue. I don't have the regs on me, but IIRC,
the conductors are required to be the same length, and without
any branches. You must show by calculation that the overload
and fault current protection will operate correctly for each conductor.
For the fault current protection, you have to consider additional
types of fault, such as one conductor shorting to ground, passing
current directly from the supply, plus that backfed from the other
end via the other conductors. Also the case where one conductor
breaks and only the backfed path is grounded, so you have a
higher earth fault loop impedance than you might otherwise
expect. For overload protection, you have to consider what
happens if one conductor breaks (without shorting). There are
probably more issues I don't recall too.

You would probably end up having to use separate but ganged
breakers for each conductor (and in the case of more than two
conductors in parallel, possibly ganged breakers at both ends of
the cable). There is simply no excuse for doing any of this in
domestic installation -- it is far cheaper to buy the correct
cable in the first place. Also, H05VV-F is flex anyway, IIRC.

--
Andrew Gabriel

In article .com,
says...
I imagine one issue is current sharing between the conductors. Whilst
the current share may be close to 50/50 when installed, any slightly
loose connection or corrosion of one conductor could cause one
conductor to end up carrying most of the current. not good.



bodge
But could be avoided by running each pair from a separate fuse, each one
rated at the maximum safe load for one pair?
/bodge

wrote in message
oups.com...
I imagine one issue is current sharing between the conductors. Whilst
the current share may be close to 50/50 when installed, any slightly
loose connection or corrosion of one conductor could cause one
conductor to end up carrying most of the current. not good.


Just like a ring main then.

"p" wrote in message
oups.com...
I want to use multicore cabel for domestic instalation ,but i dont
have 2,5 mm cable.
But I have only 4 core by 1.5 mm. Can I join the cores 2 by 2 to reach
a beter ampacity?
And what MCB for this combination? The cable marker is - H05 V V - F


This reminds me of my impoverished days 20 years ago when I'd just bought my
house and the interest rate was about 15 percent.

I had been given a second hand shower - so I bought some bright orange 3
core 13 amp FLEX from J Bull Electrical - I was going to double it up ;-)

A bit later I found some 10mm in a skip and hoarded that for "several"
years.

Fortunately I never actually got round to using either ......

I'm asking because I dont have experience in that kind of work. I juist

want to know if it is possible to use it and how much load it is
carryng. And whot ampacity of MCB to use for this.
I juist want to ack someone with better experience than me.


"" I want to use multicore cabel for domestic instalation ,but i dont
have 2,5 mm cable.
But I have only 4 core by 1.5 mm. Can I join the cores 2 by 2 to reach
a beter ampacity?
And what MCB for this combination? The cable marker is - H05 V V - F ""



Thank you!

Yes, go ahead!!
You have had good advice here but we can't stop you so it's your funeral.
By the way a 100 metre reel of 2.5 mm T&E is about £15.00 so can't believe cost is an issue??

On 16 Nov 2005 02:14:49 -0800 someone who may be "p"
wrote this:-

I'm asking because I dont have experience in that kind of work.

At least you are honest about that.

I juist want to know if it is possible to use it

It is possible to do most things, but not always advisable. Others
have given reasons from the wiring regulations why your course of
action is not advisable. I will give you another reason, you could
set the building on fire.

and how much load it is carryng.

How much load a cable carries depends on the load attached to it. So
far you have not said what the load is, or the type of circuit you
are interested in.

And whot ampacity of MCB to use for this.

The rating of an MCB depends on the load and type of cable it is
protecting (plus a few other things).

I juist want to ack someone with better experience than me.

Here is some advice. Don't try doing things with electricity, unless
you thoroughly know what you are doing. You may well kill yourself,
or someone else.


--
David Hansen, Edinburgh
I will *always* explain revoked encryption keys, unless RIP prevents me
http://www.opsi.gov.uk/acts/acts2000/00023--e.htm#54

On 15 Nov 2005 23:37:37 -0800, "p" wrote:

I want to use multicore cabel for domestic instalation ,but i dont
have 2,5 mm cable.
But I have only 4 core by 1.5 mm. Can I join the cores 2 by 2 to reach
a beter ampacity?
And what MCB for this combination? The cable marker is - H05 V V - F

In theory yes, but it is probably against regulations.

sponix

Thanks! But anyone can tell me what kind of MCB I must use for this
cable? May be 32 Amps or lower rate?

""" I want to use multicore cabel for domestic instalation ,but i dont

have 2,5 mm cable.
But I have only 4 core by 1.5 mm. Can I join the cores 2 by 2 to reach
a beter ampacity?
And what MCB for this combination? The cable marker is - H05 V V - F """

In article .com, p0
says...
Thanks! But anyone can tell me what kind of MCB I must use for this
cable? May be 32 Amps or lower rate?


If you're going to insist on using this cable doubled-up, why not just
use a nail in the fusebox? Might as well get hanged for a sheep as a
lamb..

On 16 Nov 2005 03:10:30 -0800, "p" wrote:

Thanks! But anyone can tell me what kind of MCB I must use for this
cable? May be 32 Amps or lower rate?

The way you keep on posting, we've switched from "could tell you" to
"won't tell you".

You are doing something that is forbidden, that is forbidden for good
reason, and that is only "useful" as a sheer cheapskate measure. A major
cause of electrical problems is people trying to save a little money
like this. This is not a good thing and I doubt if anyone wants to
encourage you in doing it.

You're clearly going to do this anyway, but don't ask us to assist you.

p wrote:

Thanks! But anyone can tell me what kind of MCB I must use for this
cable? May be 32 Amps or lower rate?

If you must do this against all sensible advice, then an MCB rating of
16A absolute maximum.



--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

"John Rumm" wrote in message
...
p wrote:

Thanks! But anyone can tell me what kind of MCB I must use for this
cable? May be 32 Amps or lower rate?

If you must do this against all sensible advice, then an MCB rating of 16A
absolute maximum.

Not that this is wrong, but some of the messages on this thread are inviting
this guy to frizzle himself. For all we know, he might be trying to get
power to his 45A kiln in his shed 250 feet from the CU at the bottom of his
garden. And I don't think he understands irony/sarcasm. The advice just has
to be

DON'T DO IT

In article .com,
p wrote:
I want to use multicore cabel for domestic instalation ,but i dont
have 2,5 mm cable.
But I have only 4 core by 1.5 mm. Can I join the cores 2 by 2 to reach
a beter ampacity?
And what MCB for this combination? The cable marker is - H05 V V - F

What country is this in?

--
*I took an IQ test and the results were negative.

Dave Plowman London SW
To e-mail, change noise into sound.