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 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

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 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

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

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

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

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

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/

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

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 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:
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

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 ,
(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

"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

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.
--

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....?

On Mon, 5 Jan 2004 15:37:17 -0000, R W wrote:

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

15A was radial and generally only one socket per room. Count all the
sockets in a modern house then think about the size of the CU for that
number of MCBs...

--
Cheers
Dave. pam is missing e-mail

In article ,
"R W" writes:

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

The design aim was for 3kW, which is where the 13A comes from.
I guess there probably weren't any portable appliances over 3kW
in use. Kettles of that era tended to be lower power than today's
ones. I have come across a 3kW portable convector heater which
could date back to that era, which is rather ironic as you'd be
hard pressed to find one over 2kW nowadays.

--
Andrew Gabriel

"Dave Liquorice" wrote in message
. 1...
On Mon, 5 Jan 2004 15:37:17 -0000, R W wrote:

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

15A was radial and generally only one socket per room. Count all the
sockets in a modern house then think about the size of the CU for that
number of MCBs...


Yes, but why switch from a 15 amp rated socket to one with a plug / fuse
rating of 13 amps, in other words, why a maximum of a 13 amp fuse and not a
maximum of 15 amp ?

R W wrote:

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....?






I am not sure. The technology was sold to and continues to be used in south africa.


The square pin is allegedly easier to make a decent high current self
wiping contact with than the old round pins, and I suspect what happened
was somethig like this.

(i) let's move to ring mains cos we need a LOT of sockets these days,
and we can't radial wire them all, and ringing them is a bit safer and
relaxes cable constraints.

(ii) let's go to a new and better type of plug.

(iii) now each appliance has its own plug, rather than one socket per
room (or floor?), how much do we realistically need to rate a single
point at...3KW sounds nice. Oh. Thats 13A then? Right. 13A it is...

(iv) Mmm. What will the cable stand. Ok, about 30A seems right for the
sort of cable that isn't TOO heavy. Lets standardise on 30A or 32A fuses
then.

(v) what about lights? Oh sod it. do them on spurs cos they are always a
nightmare with cables flkying everywhere, and you seldomn need a lot of
current for em. say fused at 6A - that is 12 x100w bulbs,. Thats plenty
for a house.

(vi) What about all these other plugs and sockets? Oh sell em to someone
who wants em. Africans will do.

(viii) I need to set up sockets for msall lamps on lighting
circuits...oh well use teh 5A old style plugs if you must. At least
people won't be able to plug cookers into em. and they shold take 6A
before the MCB trips.

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

Andrew Gabriel wrote:

In article ,
"R W" writes:

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


The design aim was for 3kW, which is where the 13A comes from.
I guess there probably weren't any portable appliances over 3kW
in use. Kettles of that era tended to be lower power than today's
ones. I have come across a 3kW portable convector heater which
could date back to that era, which is rather ironic as you'd be
hard pressed to find one over 2kW nowadays.



3kw convector were common in the 60's as were 3kw electric fires.

My ma's house was originally wired with 15A stuff (1953), then it was
changed to 13A stuff - still on spurs - fairly quickly, and a few bodged
extra sockets added. A seperate fuse box for the electric cooker was
added when the gas one was binned.

The main wiring is still rubber coated plated copper stranded in steel
conduit, and it has never shorted, or blown a fuse or anything.

The addons were done in the 60's using solid core stuff. Some by me.

None of it meets modern regulatons, but it all still works, and the
earths are good. No doubt when teh house is eventually sold in teh next
ten years estimnated, it will get a total reinsulate, rewire, new
bathrooms, extension etc etc. But it still soliders on in remarkably
good structural condition.

I have come across a 3kW portable convector heater which
could date back to that era, which is rather ironic as
you'd be hard pressed to find one over 2kW nowadays.

Both mine and my mother's fan heaters are 3kW. They're pretty widely
available. However, the cheapest in the range will be a 2kW, so they're
probably more common to find, as most people are cheapskates.

As for convectors, a quick browse of argos shows five 3kW, one 2.5kW and
four 2kW models available.

Christian.

In article ,
Christian McArdle wrote:
Both mine and my mother's fan heaters are 3kW. They're pretty widely
available. However, the cheapest in the range will be a 2kW, so they're
probably more common to find, as most people are cheapskates.

There's really no point in a 2kW fan heater, given that all have
thermostats.

--
*Real women don't have hot flashes, they have power surges.

Dave Plowman London SW 12
RIP Acorn

There's really no point in a 2kW fan heater, given that all have
thermostats.
I can think of two.

Firstly, the output temperature is lower. It is very easy to melt nearby
plastic things accidentally with a 3kW.

Secondly, after the room is up to temperature, I tend to knock the power
rating down to reduce cycling. I prefer the constant noise to one that goes
on and off every five minutes. If half the power of the device is too high,
then this will be less effective as it will continue to cycle rapidly.

Christian.

In article ,
Dave Plowman writes:
In article ,
Christian McArdle wrote:
Both mine and my mother's fan heaters are 3kW. They're pretty widely
available. However, the cheapest in the range will be a 2kW, so they're
probably more common to find, as most people are cheapskates.

OK. It was probably well over 10 years ago when I last looked,
and my recollection was that 2kW seemed to be the max available
then.

There's really no point in a 2kW fan heater, given that all have
thermostats.

Funny you should say that. One weekend I ended up working in an
unheated office (warehouse sized open plan one). I was given a
fan heater. On the 2kW setting, I felt nothing, but on the 1kW
setting, it sent me a nice breeze of warm air. On further
investigation, I realised that at 2kW, the exhaust air was hotter
and didn't make it more than about 2 feet from the fan heater
before just going vertically up missing me, whereas at 1kW,
the air continued to move perhaps 4 feet horizontally before
changing direction, so it caught me.

--
Andrew Gabriel

"Christian McArdle" wrote in message
et...
There's really no point in a 2kW fan heater, given that all have
thermostats.
I can think of two.

Firstly, the output temperature is lower. It is very easy to melt nearby
plastic things accidentally with a 3kW.

Secondly, after the room is up to temperature, I tend to knock the power
rating down to reduce cycling. I prefer the constant noise to one that
goes
on and off every five minutes. If half the power of the device is too
high,
then this will be less effective as it will continue to cycle rapidly.


Err, I think that last point is one that supports a 3kW fan heater! You can
only get up to temperature quickly and then turn the heat down with a 3kW
heater (or it's better at it). You can run a 3kW fan heater at 2kW but not
the other way round! I grant you the first point, especially if there is a
danger of things getting dropped near it (children's toys, things dropped by
older people, middle-aged drunks falling over etc).


--
Bob Mannix
(anti-spam is as easy as 1-2-3 - not)

Secondly, after the room is up to temperature, I tend to knock the
power rating down to reduce cycling.

Err, I think that last point is one that supports a 3kW fan heater!
You can only get up to temperature quickly and then turn the heat
down with a 3kW heater (or it's better at it).

I think you have misunderstood. In a room with a 1kW steady state
requirement, a 2kW heater will bring it up to temperature and then, on half
power, will be able to maintain it using only a minimum of annoying cycling.

A 3kW heater will bring it up even more rapidly. But then, turned down to
1.5kW, it is over sized and will switch on and off over a 3:2 duty cycle
with a period of a couple of minutes.

Christian.

"Christian McArdle" wrote in message
et...
Secondly, after the room is up to temperature, I tend to knock the
power rating down to reduce cycling.

Err, I think that last point is one that supports a 3kW fan heater!
You can only get up to temperature quickly and then turn the heat
down with a 3kW heater (or it's better at it).

I think you have misunderstood. In a room with a 1kW steady state
requirement, a 2kW heater will bring it up to temperature and then, on
half
power, will be able to maintain it using only a minimum of annoying
cycling.

A 3kW heater will bring it up even more rapidly. But then, turned down to
1.5kW, it is over sized and will switch on and off over a 3:2 duty cycle
with a period of a couple of minutes.



Well, it's not worth falling out over but (a) you didn't originally
stipulate the room had a 1kW heat load and (b), on my 3kW heater at least,
you can run the 3kW heater at 1kW, 2kW or 3kW. Generally speaking, more
flexibility is better. In any case, in a room which was heatable (ie where
you are heating a room and not one person in a warehouse) a convector heater
is far preferable, as you get no noise at all.


--
Bob Mannix
(anti-spam is as easy as 1-2-3 - not)

stipulate the room had a 1kW heat load and (b), on my 3kW heater at
least, you can run the 3kW heater at 1kW, 2kW or 3kW. Generally

Ah. A 3kW heater with 1kW and 2kW options would have no disadvantages over
the 2kW one. Mine only has a half and full option. In any case, I was only
playing devil's advocate. After all, I voted with my feet (should that be
wallet?) and got a 3kW one.

In any case, in a room which was heatable (ie where you are
heating a room and not one person in a warehouse) a convector
heater is far preferable, as you get no noise at all.

Indeed. I quite like oil filled radiators for this as well. However, you
can't beat a fan heater for emergency heat, as they are small and
lightweight, so store more easily.

My new shed will have a convector heater, though, (on a frost stat and boost
for when I'm in there). It will have 50mm Celotex/Kingspan and double
glazing, too, ever since I found out the paltry cost of sealed units. I'm
planning to store paint and decent tools in there and don't want them
freezing/rusting.

Christian.

"Christian McArdle" wrote in message
et...
stipulate the room had a 1kW heat load and (b), on my 3kW heater at
least, you can run the 3kW heater at 1kW, 2kW or 3kW. Generally


My new shed will have a convector heater, though, (on a frost stat and
boost
for when I'm in there). It will have 50mm Celotex/Kingspan and double
glazing, too, ever since I found out the paltry cost of sealed units. I'm
planning to store paint and decent tools in there and don't want them
freezing/rusting.

I have a big, old draughty garage that couldn't possibly be heated. Tools
are fine, if you give them a quick wipe over with WD40. Oil paints are fine
but water based stuff just gets thrown away eventually. A heated shed eh?,
there's posh. Better let them know on uk.rec.sheds. I'm sure they will have
some OT comments to make.


--
Bob Mannix
(anti-spam is as easy as 1-2-3 - not)