Hi
Just had a look at some 240V halogen downlighters from B&Q.
I have noticed that the bulb or rather the reflector part of it has
diffrent color to LV 12V ones /240V clear , 12V slight colour shading/
Is there any noticable diffrence between them in terms of the light output
per Watt.
and the light quality itself?

Rafal

In article ,
"Rafal" writes:
Hi
Just had a look at some 240V halogen downlighters from B&Q.
I have noticed that the bulb or rather the reflector part of it has
diffrent color to LV 12V ones /240V clear , 12V slight colour shading/
Is there any noticable diffrence between them in terms of the light output
per Watt.
and the light quality itself?

Both types are available in aluminium or dichroic reflectors.
(Actually, aluminium LV lamps have become difficult to find.)
Dichroic reflectors don't reflect the heat so the beam is
cooler, but the fitting has to be able to handle the extra
heat dumped backwards into it.

The type of reflector makes negligable difference to the light
output per watt, but the voltage difference certainly does.
The 12V lamps are significantly more efficient than 240V ones.
Also, because 12V lamps can be built with much smaller filaments,
it is possible to control the light distribution much more
accurately than with 240V ones, and you'll find a wider range of
beam angles available, with the optics also able to better
control light spill outside the intended beam.

--
Andrew Gabriel

Rafal wrote:

Just had a look at some 240V halogen downlighters from B&Q.
I have noticed that the bulb or rather the reflector part of it has
diffrent color to LV 12V ones /240V clear , 12V slight colour shading/

You may have been comparing a bulb with an standard aluminium reflector
against one with a dichroic reflector. On the latter type, the reflector
reflective to most of the visible spectrum, but translucent for some
parts of it and also for most of the infra-red wavelengths. The
advantage is they do not project as much heat forward as the standard
aluminium reflector ones. The also tend to look slightly nicer for
display lighting as the slight colour staining you get from different
angles can look quite attractive.

(you should not use dichroic bulbs unless the fitting is designed for
them, because the fitting will get hotter)

Is there any noticable diffrence between them in terms of the light output
per Watt.
and the light quality itself?

The LV ones will give more light per watt. They also have a thicker
filament and hence are more tolerant of vibration and shock.


--
Cheers,

John.

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\================================================= ================/

There is always the problem with LV ones of the transformer going... usually
it's been tucked into the most ackward of places too.

For tons of data on the different LV and Mains Voltage lamps available then
check he
http://www.tlc-direct.co.uk/Technica...a/LampData.htm

"Andrew Gabriel" wrote in message
...
In article ,
"Rafal" writes:
Hi
Just had a look at some 240V halogen downlighters from B&Q.
I have noticed that the bulb or rather the reflector part of it has
diffrent color to LV 12V ones /240V clear , 12V slight colour shading/
Is there any noticable diffrence between them in terms of the light
output
per Watt.
and the light quality itself?

Both types are available in aluminium or dichroic reflectors.
(Actually, aluminium LV lamps have become difficult to find.)
Dichroic reflectors don't reflect the heat so the beam is
cooler, but the fitting has to be able to handle the extra
heat dumped backwards into it.

The type of reflector makes negligable difference to the light
output per watt, but the voltage difference certainly does.
The 12V lamps are significantly more efficient than 240V ones.
Also, because 12V lamps can be built with much smaller filaments,
it is possible to control the light distribution much more
accurately than with 240V ones, and you'll find a wider range of
beam angles available, with the optics also able to better
control light spill outside the intended beam.

--
Andrew Gabriel

John Rumm wrote in message news:pPmac.

The LV ones will give more light per watt. They also have a thicker
filament and hence are more tolerant of vibration and shock.

And LV bulbs are a fraction the price of 240v ones. LV has all the advantages.

Regards, NT

N. Thornton wrote:

John Rumm wrote in message news:pPmac.


The LV ones will give more light per watt. They also have a thicker
filament and hence are more tolerant of vibration and shock.


And LV bulbs are a fraction the price of 240v ones. LV has all the advantages.


Apart from ease and cheapness of installation.



Regards, NT

Thank you all for excellent fedback.
Just what I needed
12V rules

Rafal

John Rumm wrote
Rafal wrote:

Just had a look at some 240V halogen downlighters from B&Q.
I have noticed that the bulb or rather the reflector part of it has
diffrent color to LV 12V ones /240V clear , 12V slight colour shading/

You may have been comparing a bulb with an standard aluminium reflector
against one with a dichroic reflector. On the latter type, the reflector
reflective to most of the visible spectrum, but translucent for some
parts of it and also for most of the infra-red wavelengths. The
advantage is they do not project as much heat forward as the standard
aluminium reflector ones. The also tend to look slightly nicer for
display lighting as the slight colour staining you get from different
angles can look quite attractive.

Hmm, that's all well and good but how does the light look in real
terms. I have LV and 240 halogens installed, the LV is clear white,
the 240V have a yellow tinge and don't appear to throw out much light.

What is this dichroic of which you speak. are these whiter ?

Cheers,

Paul.

Zymurgy wrote:

Hmm, that's all well and good but how does the light look in real
terms. I have LV and 240 halogens installed, the LV is clear white,
the 240V have a yellow tinge and don't appear to throw out much light.

I think you are right - you get more light for a given wattage from the
LV. Also you may find that with modern LV transformers (i.e. ones which
are not transformers at all, but actually small switched mode power
supplies) they will be less affected by local voltage sags and brownouts
that can give the 240V cousins a yellow tinge.

What is this dichroic of which you speak. are these whiter ?

You can get dichroic bulbs in LV and 240V although they are more common
in LV. It just describes the way in which the reflector is designed. A
standard bulb will normally have a metal (aluminium) coated reflector
that reflects like a mirror - most of the frequencies of light (and
hence infra red/heat) produced by the hot filament get projected
forward. As a result you are stuck with the natural output spectrum of a
discharge lamp - which is not very daylight like - giving the yellower
light plus lots of heat.

The dichroic (literally "having two colours" or "two frequencies")
reflectors allow some "colours" to pass through the reflector while
reflecting others. This lets you "tune" or equalise the colour of the
projected light and at the same time loose some of the projected heat
(it is still generated but more is absorbed by the light fitting).
Hence you get a different quality of light from them - making them seem
more natural and whiter. They also tend to make for slightly more
"specular" illumination. Hence shiny things seem more reflective and
sparkly, which is why they are good for shop displays and spot
highlighting in buildings.


--
Cheers,

John.

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

John Rumm wrote in message .. .
Zymurgy wrote:

Hmm, that's all well and good but how does the light look in real
terms. I have LV and 240 halogens installed, the LV is clear white,
the 240V have a yellow tinge and don't appear to throw out much light.

I think you are right - you get more light for a given wattage from the
LV. Also you may find that with modern LV transformers (i.e. ones which
are not transformers at all, but actually small switched mode power
supplies) they will be less affected by local voltage sags and brownouts
that can give the 240V cousins a yellow tinge.

What is this dichroic of which you speak. are these whiter ?

You can get dichroic bulbs in LV and 240V although they are more common
in LV. It just describes the way in which the reflector is designed. A
standard bulb will normally have a metal (aluminium) coated reflector
that reflects like a mirror - most of the frequencies of light (and
hence infra red/heat) produced by the hot filament get projected
forward. As a result you are stuck with the natural output spectrum of a
discharge lamp - which is not very daylight like - giving the yellower
light plus lots of heat.

The dichroic (literally "having two colours" or "two frequencies")
reflectors allow some "colours" to pass through the reflector while
reflecting others. This lets you "tune" or equalise the colour of the
projected light and at the same time loose some of the projected heat
(it is still generated but more is absorbed by the light fitting).
Hence you get a different quality of light from them - making them seem
more natural and whiter. They also tend to make for slightly more
"specular" illumination. Hence shiny things seem more reflective and
sparkly, which is why they are good for shop displays and spot
highlighting in buildings.

Excellent, thanks. Exactly what I wanted to know.

This ...

you are stuck with the natural output spectrum of a discharge lamp - which is not very daylight like - giving the yellower light plus lots of heat.

Is exactly what I have.

I'll try new bulbs, otherwise the fitting is coming down. Even with
200W kicking out in the kitchen it's still dull in there.

Cheers,

Paul.

What size is your kitchen? My is 3.40m X 2.40m, 2.70m high
and I planned for 4 x 50W 12V lights.
Looks like it may not be enough

Rafal wrote:

What size is your kitchen? My is 3.40m X 2.40m, 2.70m high
and I planned for 4 x 50W 12V lights.
Looks like it may not be enough




for really bright light, use anout 25W/sq meter. Which means you need
about 8 50W spots.

You will get by with 4 tho.

Thank you.
I was looking for same sort of W/sqm figure
and I definitely like a lot of light.
One more question.Came across opinion that electronic /switched mode/
transformers
are prone to overheating inside of well insulated /packed wool/ ceilings
and switching off for cooling or failing.
Is it true? All my celings are well insulated.
Rafal


"The Natural Philosopher" wrote in message ...
Rafal wrote:

What size is your kitchen? My is 3.40m X 2.40m, 2.70m high
and I planned for 4 x 50W 12V lights.
Looks like it may not be enough




for really bright light, use anout 25W/sq meter. Which means you need
about 8 50W spots.

You will get by with 4 tho.

Rafal wrote:

Thank you.
I was looking for same sort of W/sqm figure
and I definitely like a lot of light.
One more question.Came across opinion that electronic /switched mode/
transformers
are prone to overheating inside of well insulated /packed wool/ ceilings
and switching off for cooling or failing.
Is it true? All my celings are well insulated.


Both types will overheat if stuiffed inised insulation. You need to
create a (supposedly fireproof) box these days with enough airspace
round the light to allow the heat to come down to the plasterboard..

Transformers of eother type should be outsdie that box, and in a cavity
of their own.

It is NOT normal to insulate between floors of a house. Only the top
floor ceiling is normally insulated. Here in my case I have boarded the
loft, and teh transformesr (toroids) sit on top of teh bioardin in a
nice cool breeze.

If not dimming, I recommend toroids - less radio interference. In all
cases buy decemnt ones. I got all my klit from Newey and Eyre and their
oroids have been good, apart from one that kept tripping out that was
buried inisnulation for wa while, but even when pulled out it did it,
and it looked burnt, so I replaced it.

If you want, you can use a single transformer for several lamps, but
each one needs a fat piece of 13A cable at least to feed it ..in general
its easier to run 240V around and drop down locally for each lamp -
there is little in it pricewise.






Rafal


"The Natural Philosopher" wrote in message ...

Rafal wrote:


What size is your kitchen? My is 3.40m X 2.40m, 2.70m high
and I planned for 4 x 50W 12V lights.
Looks like it may not be enough




for really bright light, use anout 25W/sq meter. Which means you need
about 8 50W spots.

You will get by with 4 tho.

Reason for the insulation is to get a bit of noise reduction
from the flat above.
Looks like 240V lamps are going to be easier all around.

Rafal

"Rafal" wrote in message ...
Reason for the insulation is to get a bit of noise reduction
from the flat above.
Looks like 240V lamps are going to be easier all around.


Is it difficult to pull a couple of handfuls of insulation out and
shove the transformer in? LV will give you lower running costs both in
electricity and bulb prices.

Regards, NT

There is some space between the ceiling and the insulation anyway so fitting
a transformer
is not the problem.
Is the lack of space for heat to escape, I think.

Rafal

Is it difficult to pull a couple of handfuls of insulation out and
shove the transformer in? LV will give you lower running costs both in
electricity and bulb prices.

Regards, NT

In article ,
"Rafal" writes:
Reason for the insulation is to get a bit of noise reduction
from the flat above.

In which case the ceiling is a required fire break, and puncturing
holes in it to fitting recessed lighting is going to compromise
the fire break and would require the fitting of fire hoods over
the lights.

--
Andrew Gabriel

Hi Andrew

fire hoods? what are they?

"Andrew Gabriel" wrote in message
...
In article ,
"Rafal" writes:
Reason for the insulation is to get a bit of noise reduction
from the flat above.

In which case the ceiling is a required fire break, and puncturing
holes in it to fitting recessed lighting is going to compromise
the fire break and would require the fitting of fire hoods over
the lights.

--
Andrew Gabriel

"The Natural Philosopher" wrote in message
...

If not dimming, I recommend toroids - less radio interference. In all
cases buy decemnt ones. I got all my klit from Newey and Eyre and their
oroids have been good,

If using toroids make sure they are reasonably well matched to the load. If
the transformer can supply too much power the voltage will rise and blow
bulbs on a regular basis.

Rafal wrote:

fire hoods? what are they?

These particular ones might be slight overkill for a domestic situation,
but this should give the general idea:

http://www.tlc-direct.co.uk/Main_Ind...ght/index.html

--
Cheers,

John.

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

"Rafal" wrote
What size is your kitchen? My is 3.40m X 2.40m, 2.70m high
and I planned for 4 x 50W 12V lights.
Looks like it may not be enough

Glad it's just next door :-) - let me get my tape measure out ...

err ... 3.5 X 2.8 Metres X 2.4 high.

There's now 4 spot halogens in a line on a fitting. The fitting is 1m
long and the (adjustable) spots are spaced at 25cm intervals.

Still dull in there !

Cheers

Paul.

In article ,
John Rumm writes:
Rafal wrote:

fire hoods? what are they?

They are required where you fit recessed lights into a ceiling, which
is required to provide resistance to spread of fire, such as between
flats.

These particular ones might be slight overkill for a domestic situation,

Fire proofing between flats isn't really a domestic situation.

but this should give the general idea:

http://www.tlc-direct.co.uk/Main_Ind...ght/index.html

--
Andrew Gabriel

Rafal wrote:

There is some space between the ceiling and the insulation anyway so fitting
a transformer
is not the problem.
Is the lack of space for heat to escape, I think.


As long as there is a bit of air space you are OK.

The heat comes out via the plasteboiard into the room.


Its localises heat buildup that is the problem.



Rafal


Is it difficult to pull a couple of handfuls of insulation out and
shove the transformer in? LV will give you lower running costs both in
electricity and bulb prices.

Regards, NT

G&M wrote:

"The Natural Philosopher" wrote in message
...

If not dimming, I recommend toroids - less radio interference. In all
cases buy decemnt ones. I got all my klit from Newey and Eyre and their
oroids have been good,


If using toroids make sure they are reasonably well matched to the load.


Or of reasonable quality. A transformer that drops volts under load is
one that is wound on the limit of cost, and is one that runs hot.

If
the transformer can supply too much power the voltage will rise and blow
bulbs on a regular basis.