Hello.

While adding some sockets to my wife's study, I've found sections of
non-copper cable in my ring main. It's an old house, though the vast
majority of the wiring is less than a few decades old.

The cable has multiple strands, perhaps about 7, and is made
by Pirelli. I couldn't see a type code on it. It seems quite chunky, but
I'm surprised to see that it is not made from copper, but is probably
steel. Outwardly, it looks like regular grey T&E, but is more amenable
to bending.

Is this cable normal? I suppose my concern is that this particular ring
is quite long, and I understand that steel has a higher resistance than
copper. The ring covers rooms containing mostly lower-powered items, but
does include the washing machine.

Ewan

Ewan MacIntyre wrote:

Is this cable normal? I suppose my concern is that this particular ring
is quite long, and I understand that steel has a higher resistance than
copper. The ring covers rooms containing mostly lower-powered items, but
does include the washing machine.

I have seen tin-plated copper wire in some older installations; that
looks silver. Are you sure its steel ? Is it magnetic ? If its silver
right through, its probably aluminium, and I personally would remove
every last bit I could find.

Steve

Steve wrote:
I have seen tin-plated copper wire in some older installations; that
looks silver. Are you sure its steel ? Is it magnetic ? If its silver
right through, its probably aluminium, and I personally would remove
every last bit I could find.

Steve


I hadn't considered aluminium - I'll check with a magnet next time I
have access to it. A good excuse to go under the floor again...

Thanks

Ewan

Ewan MacIntyre wrote on Saturday (03/01/2004) :
Hello.

While adding some sockets to my wife's study, I've found sections of
non-copper cable in my ring main. It's an old house, though the vast majority
of the wiring is less than a few decades old.

The cable has multiple strands, perhaps about 7, and is made
by Pirelli. I couldn't see a type code on it. It seems quite chunky, but I'm
surprised to see that it is not made from copper, but is probably steel.
Outwardly, it looks like regular grey T&E, but is more amenable to bending.

Is this cable normal?

I would suggest it is aluminium, which would be bigger due to greater
losses and feel softer to bend. It was used in response to the high
price of copper in the 1970's.

It did have problems with poor connections resulting in over heating,
so it would be worth while replacing it with copper, along with the
sockets. The only uses I have heard of for steel, was for telecoms
where the steel was copper plated.

--

Regards,
Harry (M1BYT) (Lap)
http://www.ukradioamateur.org

"Ewan MacIntyre" wrote in
message ...
Hello.

While adding some sockets to my wife's study, I've found sections of
non-copper cable in my ring main. It's an old house, though the vast
majority of the wiring is less than a few decades old.

The cable has multiple strands, perhaps about 7, and is made
by Pirelli. I couldn't see a type code on it. It seems quite chunky, but
I'm surprised to see that it is not made from copper, but is probably
steel. Outwardly, it looks like regular grey T&E, but is more amenable
to bending.

Is this cable normal? I suppose my concern is that this particular ring
is quite long, and I understand that steel has a higher resistance than
copper. The ring covers rooms containing mostly lower-powered items, but
does include the washing machine.

Ewan


During the Rhodesia crissis ( UDI etc 1965 onwards) aluminium was used in
house wiring due to copper shortages - dreadful stuff - breaks easily at
screw terminals. During the same period stainless steel was being used for
plumbing.

OTOH are you sure that you haven't come across a bit of the old 7/029 used
around then - seven strands of 29 thou copper that was usually tin plated -
this was a pre-metrication standard.

Andrew Mawson

Andrew Mawson wrote:

"Ewan MacIntyre" wrote in
message ...

Hello.

While adding some sockets to my wife's study, I've found sections of
non-copper cable in my ring main. It's an old house, though the vast
majority of the wiring is less than a few decades old.

The cable has multiple strands, perhaps about 7, and is made
by Pirelli. I couldn't see a type code on it. It seems quite chunky, but
I'm surprised to see that it is not made from copper, but is probably
steel. Outwardly, it looks like regular grey T&E, but is more amenable
to bending.

Is this cable normal? I suppose my concern is that this particular ring
is quite long, and I understand that steel has a higher resistance than
copper. The ring covers rooms containing mostly lower-powered items, but
does include the washing machine.

Ewan



During the Rhodesia crissis ( UDI etc 1965 onwards) aluminium was used in
house wiring due to copper shortages - dreadful stuff - breaks easily at
screw terminals. During the same period stainless steel was being used for
plumbing.

OTOH are you sure that you haven't come across a bit of the old 7/029 used
around then - seven strands of 29 thou copper that was usually tin plated -
this was a pre-metrication standard.


ISTR that was pretty standard in most house in the '15A round pin plug '
era...



Andrew Mawson

In article ,
The Natural Philosopher wrote:
OTOH are you sure that you haven't come across a bit of the old 7/029
used around then - seven strands of 29 thou copper that was usually
tin plated - this was a pre-metrication standard.


ISTR that was pretty standard in most house in the '15A round pin plug '
era...

It was also used for the best part of 20 years for ring mains, too.

--
*The more people I meet, the more I like my dog.

Dave Plowman London SW 12
RIP Acorn

In article ,
Dave Plowman writes:
In article ,
The Natural Philosopher wrote:
OTOH are you sure that you haven't come across a bit of the old 7/029
used around then - seven strands of 29 thou copper that was usually
tin plated - this was a pre-metrication standard.


ISTR that was pretty standard in most house in the '15A round pin plug '
era...

It was also used for the best part of 20 years for ring mains, too.

Yes -- one of the design aims of the 30A ring circuit was easy
conversion from a 15A radial system (by making the ring start
and end at two existing 15A outlets, converted to 13A of course).
Hence the two schemes used the same cable (and you were allowed
to keep the two 15A fuses at each end of the ring early on too).

--
Andrew Gabriel

In article ,
Andrew Gabriel wrote:
ISTR that was pretty standard in most house in the '15A round pin plug '
era...

It was also used for the best part of 20 years for ring mains, too.

Yes -- one of the design aims of the 30A ring circuit was easy
conversion from a 15A radial system (by making the ring start
and end at two existing 15A outlets, converted to 13A of course).
Hence the two schemes used the same cable (and you were allowed
to keep the two 15A fuses at each end of the ring early on too).

But it was also used on new builds which only ever had ring mains until
the arrival of the current 2.5 TW&E - which was part of metrication.

--
*Marathon runners with bad footwear suffer the agony of defeat.*

Dave Plowman London SW 12
RIP Acorn

Andrew Gabriel wrote:
In article ,
Dave Plowman writes:
In article ,
The Natural Philosopher wrote:
OTOH are you sure that you haven't come across a bit of the old
7/029 used around then - seven strands of 29 thou copper that was
usually tin plated - this was a pre-metrication standard.


ISTR that was pretty standard in most house in the '15A round pin
plug ' era...

It was also used for the best part of 20 years for ring mains, too.

Yes -- one of the design aims of the 30A ring circuit was easy
conversion from a 15A radial system (by making the ring start
and end at two existing 15A outlets, converted to 13A of course).
Hence the two schemes used the same cable (and you were allowed
to keep the two 15A fuses at each end of the ring early on too).

What's the story behind the switch from 15A to 13A sockets? Surely 15A
would be more useful....?

In article ,
"Andrew Mawson" writes:

During the Rhodesia crissis ( UDI etc 1965 onwards) aluminium was used in
house wiring due to copper shortages - dreadful stuff - breaks easily at
screw terminals. During the same period stainless steel was being used for
plumbing.

OTOH are you sure that you haven't come across a bit of the old 7/029 used
around then - seven strands of 29 thou copper that was usually tin plated -
this was a pre-metrication standard.

Personally, I've only ever seen solid cored aluminium T&E.
7-stranded, if it ever existed, sounds like real recipe for
aluminium connection/oxide/fire disaster.

--
Andrew Gabriel

In article ,
Andrew Gabriel wrote:
Personally, I've only ever seen solid cored aluminium T&E.
7-stranded, if it ever existed, sounds like real recipe for
aluminium connection/oxide/fire disaster.

The old common copper house wiring sizes were 1/0.44, 3/0.29 and 7/0.29
Wonder why those sizes?

--
*You never really learn to swear until you learn to drive *

Dave Plowman London SW 12
RIP Acorn

In article ,
Ewan MacIntyre wrote:
The cable has multiple strands, perhaps about 7, and is made
by Pirelli. I couldn't see a type code on it. It seems quite chunky, but
I'm surprised to see that it is not made from copper, but is probably
steel. Outwardly, it looks like regular grey T&E, but is more amenable
to bending.

Sure it's not the old 7/0.29 copper which was tin plated? Have you cut it
to see if it's copper in the middle?

--
*Why can't women put on mascara with their mouth closed?

Dave Plowman London SW 12
RIP Acorn

On Sun, 04 Jan 2004 00:34:25 +0000 (GMT), Dave Plowman
wrote:

Sure it's not the old 7/0.29 copper which was tin plated? Have you cut it
to see if it's copper in the middle?

I'd suggest _not_ cutting it.

Neither should really be left in situ long-term (if you're already at
the floorboard lifting stage). Aluminium, in particular, has a habit
of working fine for years and then creating problems when you start to
touch it - particularly if you cut it and then try to re-join it
(screw terminals through a decades-old oxide layer - lovely).

It's a fair bet that it's either 7/0.29 or aluminium, but I think a
definitive identification can wait until it's heading for the scrap
pile.

--
Smert' spamionam

Andy Dingley wrote:
I'd suggest _not_ cutting it.

Neither should really be left in situ long-term (if you're already at
the floorboard lifting stage). Aluminium, in particular, has a habit
of working fine for years and then creating problems when you start to
touch it - particularly if you cut it and then try to re-join it
(screw terminals through a decades-old oxide layer - lovely).

It's a fair bet that it's either 7/0.29 or aluminium, but I think a
definitive identification can wait until it's heading for the scrap
pile.

--
Smert' spamionam

Thanks for all the comments.

I've now investigated the layout of the ring, and it's likely that one
or more of these cables will need replaced anyway, as I'm raising
sockets to a proper height and so the cables are too short. I'll repost
once I've cut a piece open.

Unfortunately, this same ring has my computer on it, and all our network
gear. The longer the power is off, the louder the shouts are from
upstairs that the broadband isn't working... ;-)

Ewan

"Ewan MacIntyre" wrote in
message ...
snip

Unfortunately, this same ring has my computer on it, and all our network
gear. The longer the power is off, the louder the shouts are from
upstairs that the broadband isn't working... ;-)


Time for rigging a temporary supply, if you know what's good for your ears
(and you will be able to keep us informed as to your progress - or lack off
! :~)

In article ,
Andy Dingley wrote:
Sure it's not the old 7/0.29 copper which was tin plated? Have you cut
it to see if it's copper in the middle?

I'd suggest _not_ cutting it.

I meant at an end which was being worked on - the OP stated he was
adding sockets. Sorry not to state the obvious. ;-)

--
*I don't have a solution, but I admire your problem. *

Dave Plowman London SW 12
RIP Acorn

"Dave Plowman" wrote in message
...
In article ,
Ewan MacIntyre wrote:
The cable has multiple strands, perhaps about 7, and is made
by Pirelli. I couldn't see a type code on it. It seems quite chunky, but
I'm surprised to see that it is not made from copper, but is probably
steel. Outwardly, it looks like regular grey T&E, but is more amenable
to bending.

Sure it's not the old 7/0.29 copper which was tin plated? Have you cut it
to see if it's copper in the middle?



I worked for a company that manufactured household wiring out of Aluminium,
this could be that product, I think it was last manufactured in early 70's.

Rick

Ewan MacIntyre wrote:

Hello Ewan

EM| The cable has multiple strands, perhaps about 7, and is made
EM| by Pirelli. I couldn't see a type code on it. It seems quite
EM| chunky, but I'm surprised to see that it is not made from
EM| copper, but is probably steel. Outwardly, it looks like
EM| regular grey T&E, but is more amenable to bending.

If it bends easier than copper then it's aluminium.

EM| Is this cable normal? I suppose my concern is that this
EM| particular ring is quite long, and I understand that steel
EM| has a higher resistance than copper. The ring covers rooms
EM| containing mostly lower-powered items, but does include the
EM| washing machine.

Aluminium was a big test in electrical and telecomms industries a few
decades ago. Not sure of the exact reasons why it's now not used,
apart from a rapid degradation in salt-air conditions, but it's a
common reason why adsl can't be installed and it's not used now.

--
Simon Avery, Dartmoor, UK
uk.d-i-y FAQ: http://www.diyfaq.org.uk/

In article ,
(Simon Avery) writes:

Aluminium was a big test in electrical and telecomms industries a few
decades ago. Not sure of the exact reasons why it's now not used,

Aluminium very quickly coats itself with a hard oxide layer which
is an excellent insulator*. This can make getting a good contact
area very difficult, and special techniques are required such as hard
sharp contact serrations to break through the oxide and/or chemicals
to remove and keep the oxide away until the contact is assembled.
Add to this that if you do get a poor contact and it heats up,
it rapidly gets worse, and aluminium burns (important component
in fireworks), and it's a disaster waiting to happen.

Aluminium is used in the supply infrastructure, but in that case it
is assembled by people who (in theory at least) know its dangers
and use components specifically designed for use with it.

apart from a rapid degradation in salt-air conditions, but it's a
common reason why adsl can't be installed and it's not used now.

In telephony, the problem is mainly that of dissimilar metal
corrosion, particularly in the presence of any moisture, and
very much speeded up in salt-air, acids, or alkalis. BT stuff
their streetside distribution points with desiccant bags in areas
where aluminium wiring is used. I have one aluminium phone line,
and in my experience, the connections in the streetside cabinet last
around 5-6 years before they corrode through. You get about 2 weeks
advance warning by seeing modem speed rapidly dropping off, before
finally being completely cut off, but phoning BT and saying "my
line's going to break in a week's time" just doesn't wash.

* A couple of years ago, I was breadboarding a circuit which used
a couple of power MOSFETS directly switching mains. As a temporary
measure, I used a bulldog clip to clamp a MOSFET to an aluminium
heatsink. When I got to adding the second MOSFET into the circuit,
I clamped that to the same heatsink. It was only after all the
testing when I was disassembling the breadboard circuit in order
to make up the real thing, that I suddenly realised that I'd had
full mains voltage between the two mounting surfaces of the MOSFETS.
The thin layor of aluminium oxide which inevitably forms on the
heatsink was all that stopped it going bang!

--
Andrew Gabriel

Andrew Gabriel wrote:


* A couple of years ago, I was breadboarding a circuit which used
a couple of power MOSFETS directly switching mains. As a temporary
measure, I used a bulldog clip to clamp a MOSFET to an aluminium
heatsink. When I got to adding the second MOSFET into the circuit,
I clamped that to the same heatsink. It was only after all the
testing when I was disassembling the breadboard circuit in order
to make up the real thing, that I suddenly realised that I'd had
full mains voltage between the two mounting surfaces of the MOSFETS.
The thin layor of aluminium oxide which inevitably forms on the
heatsink was all that stopped it going bang!



Yup. I done that, tho it was only 120v DC across it...

In article ,
Simon Avery wrote:
EM| The cable has multiple strands, perhaps about 7, and is made
EM| by Pirelli. I couldn't see a type code on it. It seems quite
EM| chunky, but I'm surprised to see that it is not made from
EM| copper, but is probably steel. Outwardly, it looks like
EM| regular grey T&E, but is more amenable to bending.

If it bends easier than copper then it's aluminium.

But stranded copper 7/0.29 does bend easier than 2.5 solid - especially if
rubber.

--
*Frankly, scallop, I don't give a clam

Dave Plowman London SW 12
RIP Acorn

Ewan MacIntyre wrote:
While adding some sockets to my wife's study, I've found sections of
non-copper cable in my ring main. It's an old house, though the vast
majority of the wiring is less than a few decades old.

The cable has multiple strands, perhaps about 7, and is made
by Pirelli. I couldn't see a type code on it. It seems quite chunky, but
I'm surprised to see that it is not made from copper, but is probably
steel. Outwardly, it looks like regular grey T&E, but is more amenable
to bending.

Is this cable normal? I suppose my concern is that this particular ring
is quite long, and I understand that steel has a higher resistance than
copper. The ring covers rooms containing mostly lower-powered items, but
does include the washing machine.

Hi Ewan,

I shall be very surprised indeed if this is anything but tinned
copper PVC covered cable. I have seen a lot of this around, and in
general there's nothing wrong with it, exept that it does not conform
to current standards (being multi-stranded rather than single). If
the insulation is OK (not nibbled by rats etc) it should be perfectly
OK for some considerable time to come.

J.
--

In article ,
Jerry Built ] wrote:
exept that it does not conform
to current standards (being multi-stranded rather than single).

'Twas my understanding that it's still possible to get stranded 2.5mm
singles for conduit use. And if multi-stranded cable was a no-no why is
6mm TW&E etc stranded?

--
*Do infants enjoy infancy as much as adults enjoy adultery? *

Dave Plowman London SW 12
RIP Acorn