My latest cock-up: Having dug 15M trench, put SWA cable in and
re-filled, I've now discovered it's a 3 core rather than 2 core cable.
Doh! (It did seem a little thick, but I hadn't used any SWA for a
while...) I could just go ahead and use it anyway I suppose, but since
the core colours are brown, black and grey as for 3-phase system, I
can't use the correct single phase colour scheme - there's no blue.

Is there a way round this without digging the whole bloody thing up again?

SR

SR said the following on 11/01/2006 21:48:
My latest cock-up: Having dug 15M trench, put SWA cable in and
re-filled, I've now discovered it's a 3 core rather than 2 core cable.
Doh! (It did seem a little thick, but I hadn't used any SWA for a
while...) I could just go ahead and use it anyway I suppose, but since
the core colours are brown, black and grey as for 3-phase system, I
can't use the correct single phase colour scheme - there's no blue.

Is there a way round this without digging the whole bloody thing up again?

SR
No problem

Brown - Live
Black - Neutral - with blue insulating tape over the black
Grey/Sheath - Earth - with green/yellow insulating tape over the grey

Tape should be used at both ends.

Alternatively, you can put a white label on the brown saying "L" and a
white label on the black saying "N", etc.

On Wed, 11 Jan 2006 21:48:59 +0000, SR wrote:

My latest cock-up: Having dug 15M trench, put SWA cable in and
re-filled, I've now discovered it's a 3 core rather than 2 core cable.
Doh! (It did seem a little thick, but I hadn't used any SWA for a
while...) I could just go ahead and use it anyway I suppose, but since
the core colours are brown, black and grey as for 3-phase system, I
can't use the correct single phase colour scheme - there's no blue.

Is there a way round this without digging the whole bloody thing up again?

SR

Don't worry - that's normal. I've not seen any 2 core myself, most if the
sheds sell 3 core anyway.

The consensus of opinion on the IEE forums suggest this (old and new 3
phase SWA colours used in single phase installations) (with some
differences of opinion):

RED OR BROWN - LIVE
YELLOW OR BLACK - EARTH (SLEEVED GREEN/YELLOW)
BLUE OR GREY - NEUTRAL (SLEEVED BLUE)

The whole thread is here, so best check it out yourself:

http://www.iee.org/Forums/forum/mess...&threadid=4722

The important bit is that you sleeve the conductors at each termination
correctly to indicate their true meaning, eg brown sleeve=live,
blue=neutral, yellow/green=CPC earth

I'm not an expert though I have laid SWA before. Although in many cases
the armour should make a sufficiently good earth connection, you should in
theory prove it. The easy way around is to, as is commonly done, use one
of the cores as an earth as shown above. But you must also connect the
armour to this earth CPC via the solder ring that comes as part of the
gland kit. I suspect you knew that, sorry, just being careful.

This assumes that you are exporting the supply end earth to the
destination, rather than using a local rod.

HTH

Tim

On Wed, 11 Jan 2006, SR wrote:

My latest cock-up: Having dug 15M trench, put SWA cable in and re-filled,
I've now discovered it's a 3 core rather than 2 core cable. Doh! (It did seem
a little thick, but I hadn't used any SWA for a while...) I could just go
ahead and use it anyway I suppose, but since the core colours are brown,
black and grey as for 3-phase system, I can't use the correct single phase
colour scheme - there's no blue.

Is there a way round this without digging the whole bloody thing up again?

Just use it, but ensure that the cores are properly marked with tape or
sleeving at their terminations.

The third core can be connected to earth, either at one end or both ends
if not supplying a TT installation.

--
Alistair Riddell - BOFH
Microsoft - because god hates us

On Wed, 11 Jan 2006 22:13:30 +0000, Tim S wrote:

On Wed, 11 Jan 2006 21:48:59 +0000, SR wrote:

My latest cock-up: Having dug 15M trench, put SWA cable in and
re-filled, I've now discovered it's a 3 core rather than 2 core cable.
Doh! (It did seem a little thick, but I hadn't used any SWA for a
while...) I could just go ahead and use it anyway I suppose, but since
the core colours are brown, black and grey as for 3-phase system, I
can't use the correct single phase colour scheme - there's no blue.

Is there a way round this without digging the whole bloody thing up again?

SR

Don't worry - that's normal. I've not seen any 2 core myself, most if the
sheds sell 3 core anyway.

The consensus of opinion on the IEE forums suggest this (old and new 3
phase SWA colours used in single phase installations) (with some
differences of opinion):

RED OR BROWN - LIVE
YELLOW OR BLACK - EARTH (SLEEVED GREEN/YELLOW)
BLUE OR GREY - NEUTRAL (SLEEVED BLUE)

The whole thread is here, so best check it out yourself:

http://www.iee.org/Forums/forum/mess...&threadid=4722

The important bit is that you sleeve the conductors at each termination
correctly to indicate their true meaning, eg brown sleeve=live,
blue=neutral, yellow/green=CPC earth


Don;t forget, if this is making your installation mixed old and harmonised
colours, there's a sticker you are required by the IEE regs to put on the
CU.

Tim

In article ,
SR wrote:
My latest cock-up: Having dug 15M trench, put SWA cable in and
re-filled, I've now discovered it's a 3 core rather than 2 core cable.
Doh! (It did seem a little thick, but I hadn't used any SWA for a
while...) I could just go ahead and use it anyway I suppose, but since
the core colours are brown, black and grey as for 3-phase system, I
can't use the correct single phase colour scheme - there's no blue.

Sometime before I bought this house in the early '70s, the (then) LEB
moved the meter from the cellar. The cable used by them was SWA three
phase...

--
*A clear conscience is usually the sign of a bad memory *

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

"SR" wrote in message
...
My latest cock-up: Having dug 15M trench, put SWA cable in and re-filled,
I've now discovered it's a 3 core rather than 2 core cable. Doh! (It did
seem a little thick, but I hadn't used any SWA for a while...) I could
just go ahead and use it anyway I suppose, but since the core colours are
brown, black and grey as for 3-phase system, I can't use the correct
single phase colour scheme - there's no blue.

Is there a way round this without digging the whole bloody thing up again?

SR

Are you mad? Who is going to see it unless you put a big poster on the
house. No one will know unless YOU tell them, so I don't see the problem.
A bit of common sense is required. Or you could just dig the trench up, pay
out loads more money, throw the perfectly good cable in the bin and buy new
cable.
Do you really need someone to give you the answer?

On Wed, 11 Jan 2006 22:45:45 +0000, Mike wrote:


"SR" wrote in message
...
My latest cock-up: Having dug 15M trench, put SWA cable in and re-filled,
I've now discovered it's a 3 core rather than 2 core cable. Doh! (It did
seem a little thick, but I hadn't used any SWA for a while...) I could
just go ahead and use it anyway I suppose, but since the core colours are
brown, black and grey as for 3-phase system, I can't use the correct
single phase colour scheme - there's no blue.

Is there a way round this without digging the whole bloody thing up again?

SR

Are you mad? Who is going to see it unless you put a big poster on the
house. No one will know unless YOU tell them, so I don't see the problem.
A bit of common sense is required. Or you could just dig the trench up, pay
out loads more money, throw the perfectly good cable in the bin and buy new
cable.
Do you really need someone to give you the answer?

There's no problem, he's already done it correctly even though he thought
he hadn't

"Rumble" .@. wrote in message
.. .
SR said the following on 11/01/2006 21:48:
My latest cock-up: Having dug 15M trench, put SWA cable in and
re-filled, I've now discovered it's a 3 core rather than 2 core cable.
Doh! (It did seem a little thick, but I hadn't used any SWA for a
while...) I could just go ahead and use it anyway I suppose, but since
the core colours are brown, black and grey as for 3-phase system, I can't
use the correct single phase colour scheme - there's no blue.

Is there a way round this without digging the whole bloody thing up
again?

SR
No problem

Brown - Live
Black - Neutral - with blue insulating tape over the black
Grey/Sheath - Earth - with green/yellow insulating tape over the grey

Tape should be used at both ends.

Alternatively, you can put a white label on the brown saying "L" and a
white label on the black saying "N", etc.


This is wrong. Theblack should be in ne colour 3 core cable used as the
earth and marked as such.

My latest cock-up: Having dug 15M trench, put SWA cable in and
re-filled, I've now discovered it's a 3 core rather than 2 core cable.

Not a cock up. 2 core would have been that.

I could just go ahead and use it anyway I suppose, but since the
core colours are brown, black and grey as for 3-phase system, I
can't use the correct single phase colour scheme - there's no blue.

You probably have used the right cable. It is bad idea to rely on the cable
armour for earthing (obviously it should be earthed, but just not used as
the main earthing conductor). It is much better to have a proper copper
conductor for the earth. I used 3 core for my shed.

You should sleeve the ends of the cable with the appropriate colours where
they are terminated.

Sleeve the black as blue and use as a neutral.
Use the brown as live directly.
Sleeve the grey as yellow/green and use as earth.

Connect the armour to earth at the house end or both ends according to
preference and ease.

If you are TT earthing the other end, then you don't need an earth
conductor. Just sleeve the black as blue and don't connect the grey
conductor to anythying.

Christian.

"Christian McArdle" wrote in message
...

If you are TT earthing the other end, then you don't need an earth
conductor. Just sleeve the black as blue and don't connect the grey
conductor to anythying.

It would be better to connect to grey to the armoured at both ends in this
case rather than just leaving a floating cable. The house end of couse being
connected to the house earth.

The accepted colours for such wiring is grey (sleeved with blue) used as
neutral and black (sleeved with green/yellow) used as earth.

Adam

On Fri, 13 Jan 2006 13:07:46 -0000 someone who may be "Christian
McArdle" wrote this:-

It is bad idea to rely on the cable armour for earthing

The electrical installations in many buildings rely on the cable
armour for earthing.


--
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

David Hansen wrote:

The electrical installations in many buildings rely on the cable
armour for earthing.

Indeed they do, but the point to be made is that using the armour as
earth (CPC) will always require design calculations to verify earth
fault loop impedance (for disconnection time compliance) and that the
armour will not overheat before a fault clears (adiabatic compliance).

OTOH if a copper cable core is used as the CPC you have a CPC which is
equal in size to the live circuit conductors and calculations aren't
required (provided the feeding fuse/MCB rating doesn't exceed the
current rating of the cable). The maximum circuit length (to meet both
voltage drop and disconnection time requirements can simply be looked up
in Table 7.1 of the OSG.

--
Andy

Indeed they do, but the point to be made is that using the armour as
earth (CPC) will always require design calculations to verify earth
fault loop impedance (for disconnection time compliance) and that the
armour will not overheat before a fault clears (adiabatic compliance).

Also copper doesn't rust in the same way as steel armour, so it will
continue to be safe for decades to come.

Christian.

On Tue, 17 Jan 2006 10:03:15 -0000 someone who may be "Christian
McArdle" wrote this:-

Also copper doesn't rust in the same way as steel armour, so it will
continue to be safe for decades to come.

So, are all those buildings with steel armour as the only earth
unsafe after decades?


--
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

"David Hansen" wrote in message
...
On Tue, 17 Jan 2006 10:03:15 -0000 someone who may be "Christian
McArdle" wrote this:-

Also copper doesn't rust in the same way as steel armour, so it
will
continue to be safe for decades to come.

So, are all those buildings with steel armour as the only earth
unsafe after decades?


--
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

Potentially GGGGG

AWEM

So, are all those buildings with steel armour as the only earth
unsafe after decades?

Potentially. It is one of the many reasons for the move towards TN-C-S
earthing, where the earth is carried by the neutral conductor.

Christian.

Christian McArdle wrote:

So, are all those buildings with steel armour as the only earth
unsafe after decades?

Potentially. It is one of the many reasons for the move towards TN-C-S
earthing, where the earth is carried by the neutral conductor.

Uh, that's TN-C and isn't allowed in consumers' installations.

Rusting/corrosion of steel armour wires is not a problem, galvanizing
protects well.

--
Andy

Potentially. It is one of the many reasons for the move towards TN-C-S
earthing, where the earth is carried by the neutral conductor.

Uh, that's TN-C and isn't allowed in consumers' installations.

I was talking about the incoming supply. I certainly wasn't proposing TN-C.

Rusting/corrosion of steel armour wires is not a problem, galvanizing
protects well.

It's more of a problem with the termination, where rusting can lead to high
earth loop impedence at the connection point. The armour itself shouldn't be
a problem.

Christian.

ARWadsworth wrote:
"Christian McArdle" wrote in message
...


If you are TT earthing the other end, then you don't need an earth
conductor. Just sleeve the black as blue and don't connect the grey
conductor to anythying.


It would be better to connect to grey to the armoured at both ends in this
case rather than just leaving a floating cable. The house end of couse being
connected to the house earth.

The accepted colours for such wiring is grey (sleeved with blue) used as
neutral and black (sleeved with green/yellow) used as earth.

Adam


Thanks Adam and others. I wasn't aware it was permissable to sleve the
tails to different colours. Makes life far easier. My previous
involvements with SWA cable had all used 2 core and the armour for earth
- hence my initial concern. Happy now though :-)

SR