On 23/04/17 15:29, John Rumm wrote:
On 23/04/2017 07:59, Jeff Layman wrote:
On 23/04/17 03:18, John Rumm wrote:

Its not usually a problem with lighting circuits since the cable is
significantly over specified in the first place.

Do you know if this is a hangover from the 20s and 30s when "lighting"
circuits were often used for devices with a moderate power consumption?

Not so much that, more a case of 1mm^2 is the smallest T&E used and
anything smaller would start to get a bit fragile, not to mention the
resistance would creep up - hence more brightness variation and longer
disconnect times in the event of a fault.

Also there is a (not often used) standard lighting circuit protected
with a 10A MCB, and that is somewhat closer to the 1mm^2 11.5A "in
conduit" rating for the cable.

I can most certainly remember in the 50s when my mother used to iron by
plugging it (bayonet plug) into a two-way connector in the ceiling
light. As far as I remember, the only time the 15 amp wall socket was
used was for a 2 or 3-bar heater.

Indeed... A reflection of reality that in many properties, the only
electrical provision installed was for lighting. Sockets etc came later.

With even lower power needed for lighting in these days of LEDs (and
CFLs), isn't rather a lot of metal being wasted unnecessarily in the
wire in lighting circuits?

I suppose you could install a 0.75mm^2 T&E if there were such a thing,
but I expect in most cases the savings would be marginal.

Well, although not twin and earth, there is 0.5mm^2 cable:
https://www.tlc-direct.co.uk/Products/CA0dot5F3B.html

I see this is rated at 3 amps, which is much more than is needed for LED
lighting. I reckon you'd be hard-pushed to use even 1 amp for LED
domestic lighting. The price is £19.00 for 100 metres. Compare that to
the 0.75mm^2 equivalent which is £29.00 per 100 metres
(https://www.tlc-direct.co.uk/Products/CA0dot75F3B.html) or the 1.5 mm^2
cable which is £42.00 per 100 metres
(https://www.tlc-direct.co.uk/Products/CA1F3B.html).

Quite a lot of savings to be made if you were wiring up hundreds of new
homes.

Unfortunately, as far as I can see 0.5mm^2 T&E is not made - or at least
is not available in the UK.

--

Jeff

On 24/04/2017 14:00, Jeff Layman wrote:
On 23/04/17 15:29, John Rumm wrote:
On 23/04/2017 07:59, Jeff Layman wrote:
On 23/04/17 03:18, John Rumm wrote:

Its not usually a problem with lighting circuits since the cable is
significantly over specified in the first place.

Do you know if this is a hangover from the 20s and 30s when "lighting"
circuits were often used for devices with a moderate power consumption?

Not so much that, more a case of 1mm^2 is the smallest T&E used and
anything smaller would start to get a bit fragile, not to mention the
resistance would creep up - hence more brightness variation and longer
disconnect times in the event of a fault.

Also there is a (not often used) standard lighting circuit protected
with a 10A MCB, and that is somewhat closer to the 1mm^2 11.5A "in
conduit" rating for the cable.

I can most certainly remember in the 50s when my mother used to iron by
plugging it (bayonet plug) into a two-way connector in the ceiling
light. As far as I remember, the only time the 15 amp wall socket was
used was for a 2 or 3-bar heater.

Indeed... A reflection of reality that in many properties, the only
electrical provision installed was for lighting. Sockets etc came later.

With even lower power needed for lighting in these days of LEDs (and
CFLs), isn't rather a lot of metal being wasted unnecessarily in the
wire in lighting circuits?

I suppose you could install a 0.75mm^2 T&E if there were such a thing,
but I expect in most cases the savings would be marginal.

Well, although not twin and earth, there is 0.5mm^2 cable:
https://www.tlc-direct.co.uk/Products/CA0dot5F3B.html

That's flex and not really suitable for fixed wiring.

I see this is rated at 3 amps, which is much more than is needed for LED
lighting. I reckon you'd be hard-pushed to use even 1 amp for LED
domestic lighting.

Unless they house is wired with low energy fittings that preclude the
use of other lamp types, then you still need to provision assuming 100W
at each location (or the actual wattage if greater).

The price is £19.00 for 100 metres. Compare that to
the 0.75mm^2 equivalent which is £29.00 per 100 metres

Quite a lot of savings to be made if you were wiring up hundreds of new
homes.

Unfortunately, as far as I can see 0.5mm^2 T&E is not made - or at least
is not available in the UK.

Not very practical though is it?

If we use a B3 MCB and assume a maximum circuit load of 3A that means we
will drop around 264mV per metre of cable. We are allowed 3% of 230V or
6.9V, hence we have a maximum circuit length of only 26m (and note that
includes the drops to the switch wire as well)


--
Cheers,

John.

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

On Monday, 24 April 2017 16:48:27 UTC+1, John Rumm wrote:
On 24/04/2017 14:00, Jeff Layman wrote:
On 23/04/17 15:29, John Rumm wrote:
On 23/04/2017 07:59, Jeff Layman wrote:
On 23/04/17 03:18, John Rumm wrote:

Its not usually a problem with lighting circuits since the cable is
significantly over specified in the first place.

Do you know if this is a hangover from the 20s and 30s when "lighting"
circuits were often used for devices with a moderate power consumption?

Not so much that, more a case of 1mm^2 is the smallest T&E used and
anything smaller would start to get a bit fragile, not to mention the
resistance would creep up - hence more brightness variation and longer
disconnect times in the event of a fault.

Also there is a (not often used) standard lighting circuit protected
with a 10A MCB, and that is somewhat closer to the 1mm^2 11.5A "in
conduit" rating for the cable.

I can most certainly remember in the 50s when my mother used to iron by
plugging it (bayonet plug) into a two-way connector in the ceiling
light. As far as I remember, the only time the 15 amp wall socket was
used was for a 2 or 3-bar heater.

Indeed... A reflection of reality that in many properties, the only
electrical provision installed was for lighting. Sockets etc came later.

On 24/04/2017 17:20, wrote:

1mm2 drops 44mV per metre of both conductors, 0.5 would thus be 88mV.

Per meter *per amp*



--
Cheers,

John.

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

On Monday, 24 April 2017 18:14:05 UTC+1, John Rumm wrote:
On 24/04/2017 17:20, tabbypurr wrote:

1mm2 drops 44mV per metre of both conductors, 0.5 would thus be 88mV.

Per meter *per amp*

Oh yes So it's 26m radial, 52m ring. That's workable in many flats.

I suspect the future will see incadescents disappear more or less entirely, and the 100w per fitting drop to half or less.


NT

On 23/04/2017 21:42, charles wrote:
In article . com,
dennis@home wrote:
On 23/04/2017 18:57, charles wrote:
In article ,
ARW wrote:
On 23/04/2017 11:24, charles wrote:
In article . com,
dennis@home wrote:
On 23/04/2017 07:38, wrote:

pendant lights are rated 100w max.

Never put a photoflood 2 lamp in a pendant before?

and we used to have 200w ES ones in our village hall. Now using 120w
halogens - when I can still get them.


LED next?

possibly - but I haven't seen any with sufficient output yet and they'd
need to be dimmable.


You can certainly get them bright enough..

https://www.amazon.co.uk/Dephen-Repl.../dp/B01FJQG9YA

I don't think our hirers would like such a "cold" colour temperature

Finding a dimmable one will require a bit more googling.

I'd prefer to look at a trade show.

Fitting new LED panels is probably a better idea.

but it would probably involve a major rewiring job - and would involve
scaffolding because of the ceiling height. That might mean closing the hall
to hirers for a week. Not a good idea.


How high are the ceilings?

Care to post a photo of them and the existing light fittings? That way
the next time I see something similar (or work on something similar)
that has been redone with LEDs I can take some photos and give you some
ideas to pinch for future use.

I do from time to time work in church halls, village halls and similar
buildings. I always find them to be one of the most rewarding of jobs.

--
Adam

On 23/04/2017 19:00, charles wrote:
In article ,
John Rumm wrote:
On 23/04/2017 07:59, Jeff Layman wrote:
On 23/04/17 03:18, John Rumm wrote:

Its not usually a problem with lighting circuits since the cable is
significantly over specified in the first place.

Do you know if this is a hangover from the 20s and 30s when "lighting"
circuits were often used for devices with a moderate power consumption?

Not so much that, more a case of 1mm^2 is the smallest T&E used and
anything smaller would start to get a bit fragile, not to mention the
resistance would creep up - hence more brightness variation and longer
disconnect times in the event of a fault.

Also there is a (not often used) standard lighting circuit protected
with a 10A MCB, and that is somewhat closer to the 1mm^2 11.5A "in
conduit" rating for the cable.

I can most certainly remember in the 50s when my mother used to iron by
plugging it (bayonet plug) into a two-way connector in the ceiling
light. As far as I remember, the only time the 15 amp wall socket was
used was for a 2 or 3-bar heater.

Indeed... A reflection of reality that in many properties, the only
electrical provision installed was for lighting. Sockets etc came later.

Our first house, wired in 1947, had 4 "power points"; one in each bedroom
and one in the kitchen. There was a 2A socket off the lighting circuit in
the living room.


That would have been a posh install:-)

--
Adam

On 24/04/2017 11:51, Tricky Dicky wrote:
My mum's 1968 bungalow had *no* sockets in the third bedroom.

My 1968 council flat was comparatively well equipped with 2 sockets in each bedroom and lounge and *three* in the kitchen plus a cooker point.

The new build my parents bought in 1962 had no sockets in the third bedroom, one single in each of the other bedrooms, two singles in the through lounge, three singles in the kitchen only because one should have been a cooker point but they opted for gas and a single in the corridor. I think in those days you got what you were given and there were no options for adding additional sockets. Oddly enough there was provision for two wall lights as well as a centre light in the lounge, fortunetly they did not go for those "Clam shell" types that were all the rage in the 50s.


About right. My parents 1969 build was 2 single sockets per room (only
one in the small bedroom). Gas CH was an optional extra (the coal fire
was included in the price).

All sockets done on one 4mm radial circuit.

--
Adam

On 24/04/2017 16:48, John Rumm wrote:

If we use a B3 MCB and assume a maximum circuit load of 3A that means we
will drop around 264mV per metre of cable. We are allowed 3% of 230V or
6.9V, hence we have a maximum circuit length of only 26m (and note that
includes the drops to the switch wire as well)



But those drops assume tungsten lights and current 240V LEDs will work
down to about 130 volts and they could be made to work a lot lower.
If you were hard wiring LED lamps you could ignore the 3% rule and not
have any problems.

Once we go back to all tungsten lights after brexit the 3% rule will be
essential.

"ARW" wrote in message
news
On 23/04/2017 21:42, charles wrote:
In article . com,
dennis@home wrote:
On 23/04/2017 18:57, charles wrote:
In article ,
ARW wrote:
On 23/04/2017 11:24, charles wrote:
In article . com,
dennis@home wrote:
On 23/04/2017 07:38, wrote:

pendant lights are rated 100w max.

Never put a photoflood 2 lamp in a pendant before?

and we used to have 200w ES ones in our village hall. Now using 120w
halogens - when I can still get them.


LED next?

possibly - but I haven't seen any with sufficient output yet and they'd
need to be dimmable.


You can certainly get them bright enough..

https://www.amazon.co.uk/Dephen-Repl.../dp/B01FJQG9YA

I don't think our hirers would like such a "cold" colour temperature

Finding a dimmable one will require a bit more googling.

I'd prefer to look at a trade show.

Fitting new LED panels is probably a better idea.

but it would probably involve a major rewiring job - and would involve
scaffolding because of the ceiling height. That might mean closing the
hall
to hirers for a week. Not a good idea.


How high are the ceilings?

Care to post a photo of them and the existing light fittings? That way the
next time I see something similar (or work on something similar) that has
been redone with LEDs I can take some photos and give you some ideas to
pinch for future use.

I do from time to time work in church halls, village halls and similar
buildings. I always find them to be one of the most rewarding of jobs.

But that’s because you help yourself from the collection box.

On 24/04/2017 20:24, dennis@home wrote:
On 24/04/2017 16:48, John Rumm wrote:

If we use a B3 MCB and assume a maximum circuit load of 3A that means
we will drop around 264mV per metre of cable. We are allowed 3% of
230V or 6.9V, hence we have a maximum circuit length of only 26m (and
note that includes the drops to the switch wire as well)



But those drops assume tungsten lights and current 240V LEDs will work
down to about 130 volts and they could be made to work a lot lower.
If you were hard wiring LED lamps you could ignore the 3% rule and not
have any problems.

Once we go back to all tungsten lights after brexit the 3% rule will be
essential.

Why would we do that? Is electricity going to be free after Brexit?


--
Adam

On Monday, 24 April 2017 20:24:12 UTC+1, dennis@home wrote:
On 24/04/2017 16:48, John Rumm wrote:

If we use a B3 MCB and assume a maximum circuit load of 3A that means we
will drop around 264mV per metre of cable. We are allowed 3% of 230V or
6.9V, hence we have a maximum circuit length of only 26m (and note that
includes the drops to the switch wire as well)



But those drops assume tungsten lights and current 240V LEDs will work
down to about 130 volts and they could be made to work a lot lower.
If you were hard wiring LED lamps you could ignore the 3% rule and not
have any problems.

Once we go back to all tungsten lights after brexit the 3% rule will be
essential.

You can ignore lots of rules and not have problems, old buildings do, but you've still got to follow them.


NT

On 24/04/2017 20:24, dennis@home wrote:
On 24/04/2017 16:48, John Rumm wrote:

If we use a B3 MCB and assume a maximum circuit load of 3A that means
we will drop around 264mV per metre of cable. We are allowed 3% of
230V or 6.9V, hence we have a maximum circuit length of only 26m (and
note that includes the drops to the switch wire as well)



But those drops assume tungsten lights and current 240V LEDs will work
down to about 130 volts and they could be made to work a lot lower.
If you were hard wiring LED lamps you could ignore the 3% rule and not
have any problems.

You could, although a deviation from the current regs. However you then
rely on the user to not change the lamps unless you use low energy
fittings only to force their choice.


--
Cheers,

John.

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

On 24/04/2017 21:02, ARW wrote:
On 24/04/2017 20:24, dennis@home wrote:
On 24/04/2017 16:48, John Rumm wrote:

If we use a B3 MCB and assume a maximum circuit load of 3A that means
we will drop around 264mV per metre of cable. We are allowed 3% of
230V or 6.9V, hence we have a maximum circuit length of only 26m (and
note that includes the drops to the switch wire as well)



But those drops assume tungsten lights and current 240V LEDs will work
down to about 130 volts and they could be made to work a lot lower.
If you were hard wiring LED lamps you could ignore the 3% rule and not
have any problems.

Once we go back to all tungsten lights after brexit the 3% rule will be
essential.

Why would we do that? Is electricity going to be free after Brexit?



Isn't everything going to be cheap after brexit?

"dennis@home" wrote in message
web.com...
On 24/04/2017 21:02, ARW wrote:
On 24/04/2017 20:24, dennis@home wrote:
On 24/04/2017 16:48, John Rumm wrote:

If we use a B3 MCB and assume a maximum circuit load of 3A that means
we will drop around 264mV per metre of cable. We are allowed 3% of
230V or 6.9V, hence we have a maximum circuit length of only 26m (and
note that includes the drops to the switch wire as well)



But those drops assume tungsten lights and current 240V LEDs will work
down to about 130 volts and they could be made to work a lot lower.
If you were hard wiring LED lamps you could ignore the 3% rule and not
have any problems.

Once we go back to all tungsten lights after brexit the 3% rule will be
essential.

Why would we do that? Is electricity going to be free after Brexit?



Isn't everything going to be cheap after brexit?

Nope, wages are sposed to go up after BRexit, stupid.

On 24/04/2017 21:02, ARW wrote:
On 24/04/2017 20:24, dennis@home wrote:
On 24/04/2017 16:48, John Rumm wrote:

If we use a B3 MCB and assume a maximum circuit load of 3A that means
we will drop around 264mV per metre of cable. We are allowed 3% of
230V or 6.9V, hence we have a maximum circuit length of only 26m (and
note that includes the drops to the switch wire as well)



But those drops assume tungsten lights and current 240V LEDs will work
down to about 130 volts and they could be made to work a lot lower.
If you were hard wiring LED lamps you could ignore the 3% rule and not
have any problems.

Once we go back to all tungsten lights after brexit the 3% rule will be
essential.

Why would we do that? Is electricity going to be free after Brexit?

CFLs were never about saving us money, or it would have been left up to
us which sort of light we use.

--
Max Demian

On 24/04/2017 23:19, dennis@home wrote:
On 24/04/2017 21:02, ARW wrote:
On 24/04/2017 20:24, dennis@home wrote:
On 24/04/2017 16:48, John Rumm wrote:

If we use a B3 MCB and assume a maximum circuit load of 3A that means
we will drop around 264mV per metre of cable. We are allowed 3% of
230V or 6.9V, hence we have a maximum circuit length of only 26m (and
note that includes the drops to the switch wire as well)



But those drops assume tungsten lights and current 240V LEDs will work
down to about 130 volts and they could be made to work a lot lower.
If you were hard wiring LED lamps you could ignore the 3% rule and not
have any problems.

Once we go back to all tungsten lights after brexit the 3% rule will be
essential.

Why would we do that? Is electricity going to be free after Brexit?



Isn't everything going to be cheap after brexit?

Not the French prostitutes.




--
Adam