I understand that linear tungsten halogen bulbs emit noticeably more
UV light than general household incandescent bulbs.

Would it be safe to use a 300 Watt tunsten halogen floodlight as a
good bright light in my home office?

This would be on for approx 8 hours a day. I'm wondering that maybe
after that sort of exposure the extra UV could become a significant
adverse effect on eyes & skin.

On Thu, 01 Dec 2005 10:00:21 GMT, JS
wrote:

I understand that linear tungsten halogen bulbs emit noticeably more
UV light than general household incandescent bulbs.

Would it be safe to use a 300 Watt tunsten halogen floodlight as a
good bright light in my home office?

This would be on for approx 8 hours a day. I'm wondering that maybe
after that sort of exposure the extra UV could become a significant
adverse effect on eyes & skin.

It's generally inadvisable to use these indoors because of fire risk.

--
Frank Erskine

Would it be safe to use a 300 Watt tunsten halogen floodlight as a
good bright light in my home office?

They are not suitable.

Use high frequency tri phosphor tubes. They have the additional advantage of
not using an obscene quantity of carbon dioxide emmisions for the same
output.

Christian.

On Thu, 01 Dec 2005 10:00:21 GMT, JS wrote:

I understand that linear tungsten halogen bulbs emit noticeably more
UV light than general household incandescent bulbs.

Would it be safe to use a 300 Watt tunsten halogen floodlight as a
good bright light in my home office?

This would be on for approx 8 hours a day. I'm wondering that maybe
after that sort of exposure the extra UV could become a significant
adverse effect on eyes & skin.

If there is no glass between you and the bulb then it would definitely be hazardous - this is why
dichroic bulbs for table lamps have a cover glass on the front.
I don't know if glass attenuates UV sufficiently to be safe for long-term exposure.

For office lighting, you really don't want a single-point source, as it casts shadows too much - you
would want to at least uplight it onto a white ceiling.

Fluorescents would probably be much better.

JS wrote:
I understand that linear tungsten halogen bulbs emit noticeably more
UV light than general household incandescent bulbs.

Would it be safe to use a 300 Watt tunsten halogen floodlight as a
good bright light in my home office?

This would be on for approx 8 hours a day. I'm wondering that maybe
after that sort of exposure the extra UV could become a significant
adverse effect on eyes & skin.

Halogens are fine for indoor use from a UV pov. But they run intensely
hot, and are thus a fire risk if used in plugin lamps, or near high
shelves. The light source is also very intense, so direct view should
be prevented. Theyre not especially energy efficient or long lived. And
300w is a bit much for your average home office, though it would be
fine if its large and has a high ceiling. I've worked in a high ceiling
room lit by 3x 500w halogens, and the only noticeable difference was
harder shadows, plus looking up just wasnt something anyone wanted to
do.

CFLs might be a better choice, as long as you pick good quality bulbs.
If you really do need the 300w, a 5' linear fluorescent can also work
very well, but ony if installed well - which unfortunately is usually
not whats done. Linear flourescents go well with trough fittings.


NT

"JS" wrote in message
...
I understand that linear tungsten halogen bulbs emit noticeably more
UV light than general household incandescent bulbs.

Would it be safe to use a 300 Watt tunsten halogen floodlight as a
good bright light in my home office?

This would be on for approx 8 hours a day. I'm wondering that maybe
after that sort of exposure the extra UV could become a significant
adverse effect on eyes & skin.

To answer your question -- yes, tungsten halogen lamps do emit substantial
amounts of UV and they are perfectly capable of causing skin and eye damage
if you are directly exposed to the light of an unshielded lamp. In Italy
some years ago, users of small halogen task lamps reported sunburn and other
UV-related problems because the lamps were not shielded.

But a piece of glass will filter the UV to minimum levels and the halogen
lamps should be enclosed anyway in case of bulb rupture. You definitely
don't want to experience that in a home office situation.

As others have said, however, there are much better, more efficient and
safer ways to light your office using fluorescent lamps.

Terry McGowan

wrote in message
oups.com...

And
300w is a bit much for your average home office, though it would be
fine if its large and has a high ceiling.

I disagree.
I used to have a 250W high pressure discharge lamp in an uplighter for
general illumination in my home.
It makes doing anything fiddly much easier than the pathetic light you get
from most domestic fittings.

On 12/1/05 7:11 AM, in article
, "TKM"
wrote:


"JS" wrote in message
...
I understand that linear tungsten halogen bulbs emit noticeably more
UV light than general household incandescent bulbs.

Would it be safe to use a 300 Watt tunsten halogen floodlight as a
good bright light in my home office?

This would be on for approx 8 hours a day. I'm wondering that maybe
after that sort of exposure the extra UV could become a significant
adverse effect on eyes & skin.

To answer your question -- yes, tungsten halogen lamps do emit substantial
amounts of UV and they are perfectly capable of causing skin and eye damage
if you are directly exposed to the light of an unshielded lamp. In Italy
some years ago, users of small halogen task lamps reported sunburn and other
UV-related problems because the lamps were not shielded.

But a piece of glass will filter the UV to minimum levels and the halogen
lamps should be enclosed anyway in case of bulb rupture. You definitely
don't want to experience that in a home office situation.

As others have said, however, there are much better, more efficient and
safer ways to light your office using fluorescent lamps.

Terry McGowan


I agree with this. To withstand the high temperature, the envelope is made
from fused silica.

In addition, if you can get it, nonex glass (trade marked by Corning) is a
borosilicate glass that is ostensibly transparent but very good at blocking
soft UV. There probably are similar competitive products.

Bill

-- Ferme le Bush

In article ,
"TKM" writes:

To answer your question -- yes, tungsten halogen lamps do emit substantial
amounts of UV and they are perfectly capable of causing skin and eye damage
if you are directly exposed to the light of an unshielded lamp. In Italy
some years ago, users of small halogen task lamps reported sunburn and other
UV-related problems because the lamps were not shielded.

We had the same issue in the UK.

--
Andrew Gabriel

In message .com,
writes
Halogens are fine for indoor use from a UV pov. But they run intensely
hot, and are thus a fire risk if used in plugin lamps, or near high
shelves. The light source is also very intense, so direct view should
be prevented. Theyre not especially energy efficient or long lived. And
300w is a bit much for your average home office, though it would be
fine if its large and has a high ceiling. I've worked in a high ceiling
room lit by 3x 500w halogens, and the only noticeable difference was
harder shadows, plus looking up just wasnt something anyone wanted to do.

I use a 300W floodlight with glass front and wire shield above my
workshop bench. I like the heat and sheer intensity of the light which
feels like working in the sun. This is particularly nice in the winter.
The genuinely full spectrum of a tungsten halogen lamp would make it the
ideal SAD lamp.

The lamps last a LONG time and are extremely cheap.

--
Clive Mitchell
http:/www.bigclive.com

On Thu, 1 Dec 2005, TKM wrote:

yes, tungsten halogen lamps do emit substantial amounts of UV and they
are perfectly capable of causing skin and eye damage if you are directly
exposed to the light of an unshielded lamp.

They can also cause polycarbonate damage if the polycarbonate is directly
exposed to the light of an unshielded lamp.

DS (Yes, I'm kvetching about poor US headlamp specs again)

TKM wrote:

But a piece of glass will filter the UV to minimum levels and the halogen
lamps should be enclosed anyway in case of bulb rupture. You definitely
don't want to experience that in a home office situation.

I had a 500 watt halogen linear fail after being dropped.

I was working on a pint job and moved the lamp to an unstable position.
It fell, and continued working. I thought: these are quite sturdy, and
put it in a more stable position and continued working. After that, a
pretty loud bang and the house fuse blowing.

The tube had blown a hole and spewed out it's length of filament, which
was quite long - it could have hit me if I was working nearby. But with
the fuse blowing, at least I wouldn't have been electrocuted, I suppose.


Thomas

In message
.com,
writes
Halogens are fine for indoor use from a UV pov. But they run
intensely hot, and are thus a fire risk if used in plugin lamps,
or near high shelves. The light source is also very intense, so
direct view should be prevented. Theyre not especially energy
efficient or long lived. And 300w is a bit much for your average
home office, though it would be fine if its large and has a high
ceiling. I've worked in a high ceiling room lit by 3x 500w
halogens, and the only noticeable difference was harder shadows,
plus looking up just wasnt something anyone wanted to do.


On Thu 01 Dec 2005 20:48:44, Clive Mitchell

I use a 300W floodlight with glass front and wire shield above
my workshop bench. I like the heat and sheer intensity of the
light which feels like working in the sun. This is particularly
nice in the winter. The genuinely full spectrum of a tungsten
halogen lamp would make it the ideal SAD lamp.

The lamps last a LONG time and are extremely cheap.

Clive, what you say is a like the way I would use the lamp ...

Nice and bright light. Less (sleepy) orangey color temperature than
general light bulb. An intensity which helps with the sense of
getting your head down to work. And so on. Yup, maybe it's a way of
addressing SAD.

I find the flourescent tube which otehrs suggest to be disppointing
but I haven't tried the better ones and I haven't tried them such
that together they give a high level of illumination.

"JS" wrote in message

I understand that linear tungsten halogen bulbs emit
noticeably more
UV light than general household incandescent bulbs.

Would it be safe to use a 300 Watt tunsten halogen floodlight
as a good bright light in my home office?

This would be on for approx 8 hours a day. I'm wondering that
maybe after that sort of exposure the extra UV could become a
significant adverse effect on eyes & skin.


On Thu 01 Dec 2005 15:11:31, TKM wrote:

-- snip --

But a piece of glass will filter the UV to minimum levels and
the halogen lamps should be enclosed anyway in case of bulb
rupture. You definitely don't want to experience that in a home
office situation.

Would any glass hold back a reasonable amount of UV?

I would guess that the glass used in many of the cheap doemestic
floodlights is probably not all that specialised..

On Thu, 01 Dec 2005 20:48:44 GMT, Clive Mitchell wrote:

In message .com,
writes
Halogens are fine for indoor use from a UV pov. But they run intensely
hot, and are thus a fire risk if used in plugin lamps, or near high
shelves. The light source is also very intense, so direct view should
be prevented. Theyre not especially energy efficient or long lived. And
300w is a bit much for your average home office, though it would be
fine if its large and has a high ceiling. I've worked in a high ceiling
room lit by 3x 500w halogens, and the only noticeable difference was
harder shadows, plus looking up just wasnt something anyone wanted to do.

I use a 300W floodlight with glass front and wire shield above my
workshop bench. I like the heat and sheer intensity of the light which
feels like working in the sun. This is particularly nice in the winter.
The genuinely full spectrum of a tungsten halogen lamp would make it the
ideal SAD lamp.

The lamps last a LONG time and are extremely cheap.
Clive Mitchell
http:/www.bigclive.com

....and see the above website ('Things to Make & Do' - Make a Chandelier) for a halogen lighting
fixture where UV is the least of your worries.... great stuff!

In message , JS
writes
Would any glass hold back a reasonable amount of UV?

I would guess that the glass used in many of the cheap doemestic
floodlights is probably not all that specialised..

Yes. Common glass blocks UV. The problem with UV emission from some
lamps is because they are made of quartz which doesn't generally block
UV.

Some modern lamps have UV filtration incorporated.

--
Clive Mitchell
http:/www.bigclive.com

"JS" wrote

snip

I find the flourescent tube which otehrs suggest to be disppointing
but I haven't tried the better ones and I haven't tried them such
that together they give a high level of illumination.

Tri-phospher as someone has suggested are totally different to normal tubes
the light is intense enough to make looking at them very uncomfortable

Regards Jeff

In uk.d-i-y Clive Mitchell wrote:
In message , JS
writes
Would any glass hold back a reasonable amount of UV?

I would guess that the glass used in many of the cheap doemestic
floodlights is probably not all that specialised..

Yes. Common glass blocks UV. The problem with UV emission from some
lamps is because they are made of quartz which doesn't generally block
UV.

Some modern lamps have UV filtration incorporated.

Surely any lamp fitting which uses one of the linear quartz-halogen
bulbs is *required* to have some sort of shield. Certainly all the
ones I have used have a shield (glass in every case I've seen) and the
instructions have warnings to say that if the shield is broken it must
be replaced with something offering equivalent protection.

This would have protected that poster who was having a pint when the
lamp exploded too! :-)

--
Chris Green

On Fri, 2 Dec 2005 09:49:47 -0000, "Jeff"
wrote:


"JS" wrote

snip

I find the flourescent tube which otehrs suggest to be disppointing
but I haven't tried the better ones and I haven't tried them such
that together they give a high level of illumination.

Tri-phospher as someone has suggested are totally different to normal tubes
the light is intense enough to make looking at them very uncomfortable

It's probably not the tri-phosphor but the tube diameter.
Modern T5 lamps, not the old switch-start variety, have a
high surface brightness, and T8 lamps have a higher surface
brightness than T12 lamps, but not so high that most people
will be uncomfortable looking at them. You can also find T12
lamps with tri-phosphor, but they are rather expensive.

--
Vic Roberts
http://www.RobertsResearchInc.com
To reply via e-mail:
replace xxx with vdr in the Reply to: address
or use e-mail address listed at the Web site.

This information is provided for educational purposes only.
It may not be used in any publication or posted on any Web
site without written permission.

JS wrote:
"JS" wrote in message

I understand that linear tungsten halogen bulbs emit
noticeably more
UV light than general household incandescent bulbs.

Would it be safe to use a 300 Watt tunsten halogen floodlight
as a good bright light in my home office?

This would be on for approx 8 hours a day. I'm wondering that
maybe after that sort of exposure the extra UV could become a
significant adverse effect on eyes & skin.


On Thu 01 Dec 2005 15:11:31, TKM wrote:

-- snip --

But a piece of glass will filter the UV to minimum levels and
the halogen lamps should be enclosed anyway in case of bulb
rupture. You definitely don't want to experience that in a home
office situation.

Would any glass hold back a reasonable amount of UV?

Yes, that's why you don't get sunburn sitting by the window indoors.

MBQ

Underwriters Laboratory requires some sort of sheilding, although in
some cases it is wire mesh rather than glass. (In case of "Non-passive
Failure" - my favorite techno term, thanks to GE.) This covers 99% of
North American instalations and equipment.

This UV scare has been going on for well over ten years. There was an
experiment in Italy where they baked some hairless mice with unsheilded
lamps. Gee, they developed skin problems. The press went wild....
***You get more UV walking to your car than from sitting under halogen
lamps.***

Note to JS: As you noticed lighting is not cut and dried, there are
many options and the best solution depends on the details of your
situation. Energy, quality, dimming, start-up, first costs, space,
style, your age!, type of work....

Good Luck

wrote:

Surely any lamp fitting which uses one of the linear quartz-halogen
bulbs is *required* to have some sort of shield. Certainly all the
ones I have used have a shield (glass in every case I've seen) and the
instructions have warnings to say that if the shield is broken it must
be replaced with something offering equivalent protection.

The majority of high power fittings I've seen here (uk) had no shield
of any kind. By high power I mean 500w and 1kW lamps. This includes
indoor and outdoor fittings. Little 50 watters are different, with the
majority having a glass shield.

NT

I have a couple of those task lights (from China) that had round glass
filters on them. In both cases the filters broke. Is there a source to
get replacements?

TKM wrote:

"snip

To answer your question -- yes, tungsten halogen lamps do emit substantial
amounts of UV and they are perfectly capable of causing skin and eye damage
if you are directly exposed to the light of an unshielded lamp. In Italy
some years ago, users of small halogen task lamps reported sunburn and other
UV-related problems because the lamps were not shielded.

But a piece of glass will filter the UV to minimum levels and the halogen
lamps should be enclosed anyway in case of bulb rupture. You definitely
don't want to experience that in a home office situation.

As others have said, however, there are much better, more efficient and
safer ways to light your office using fluorescent lamps.

Terry McGowan





--
Joe Leikhim K4SAT
"The RFI-EMI-GUY"

"Follow The Money"

So you are talking about all those crappy Dodge NEON 's running around
with fogged headlamps? The DOT should force a recall of those!

Daniel J. Stern wrote:

snip


They can also cause polycarbonate damage if the polycarbonate is
directly exposed to the light of an unshielded lamp.

DS (Yes, I'm kvetching about poor US headlamp specs again)


--
Joe Leikhim K4SAT
"The RFI-EMI-GUY"

"Follow The Money"

On Sun, 4 Dec 2005, **THE-RFI-EMI-GUY** wrote:

So you are talking about all those crappy Dodge NEON 's running around with
fogged headlamps?

Chryslers, Fords, Mazdas, Subarus, Nissans, Volvos...

The DOT should force a recall of those!

The DOT wrote the inferior testing standard that lets them degrade this
way.

On Fri 02 Dec 2005 11:49:37, Victor Roberts
wrote:

Tri-phospher as someone has suggested are totally different to
normal tubes the light is intense enough to make looking at them
very uncomfortable

It's probably not the tri-phosphor but the tube diameter.
Modern T5 lamps, not the old switch-start variety, have a
high surface brightness, and T8 lamps have a higher surface
brightness than T12 lamps, but not so high that most people
will be uncomfortable looking at them. You can also find T12
lamps with tri-phosphor, but they are rather expensive.

I am newbie when it comes to lighting. I have not come across these
T lamp bulbs.

Is there a web page which show pictures or diagrams of the T lamps
(T5, T8, etc) so I can see how they differ from one another.

Google gives me lots of hits but nothing which illutrates or compares
these lights on a single page.

In article ,
JS writes:
I am newbie when it comes to lighting. I have not come across these
T lamp bulbs.

Is there a web page which show pictures or diagrams of the T lamps
(T5, T8, etc) so I can see how they differ from one another.

These are regular fluorescent tubes.
The number following the T is the diameter in 1/8ths of an inch.
(Some EU countries give the T-number in mm's instead, but not UK.)

--
Andrew Gabriel

On Sun, 04 Dec 2005 13:02:56 GMT, JS
wrote:

On Fri 02 Dec 2005 11:49:37, Victor Roberts
wrote:

Tri-phospher as someone has suggested are totally different to
normal tubes the light is intense enough to make looking at them
very uncomfortable

It's probably not the tri-phosphor but the tube diameter.
Modern T5 lamps, not the old switch-start variety, have a
high surface brightness, and T8 lamps have a higher surface
brightness than T12 lamps, but not so high that most people
will be uncomfortable looking at them. You can also find T12
lamps with tri-phosphor, but they are rather expensive.

I am newbie when it comes to lighting. I have not come across these
T lamp bulbs.

Is there a web page which show pictures or diagrams of the T lamps
(T5, T8, etc) so I can see how they differ from one another.

Google gives me lots of hits but nothing which illutrates or compares
these lights on a single page.

Sorry. The T stands for tubular and the number, at least in
the US, gives the diameter in 1/8" increments. A T8 lamp is
a tubular lamp with a diameter of 1 inch. A T12 lamp has a
diameter of 1.5 inches. A T5 lamp has a diameter of 5/8
inch.

--
Vic Roberts
http://www.RobertsResearchInc.com
To reply via e-mail:
replace xxx with vdr in the Reply to: address
or use e-mail address listed at the Web site.

This information is provided for educational purposes only.
It may not be used in any publication or posted on any Web
site without written permission.

But a piece of glass will filter the UV to minimum levels and the halogen
lamps should be enclosed anyway in case of bulb rupture. You definitely
don't want to experience that in a home office situation.

As others have said, however, there are much better, more efficient and
safer ways to light your office using fluorescent lamps.


We had a case here in Oregon a year or two ago. Seems a large group
of teachers was holding an institute day in the school gym under the
metal halide lamps. Unknown to everyone who attended, one of the UV
shields was broken and the teachers were exposed to high levels of UV
exposure all day. Apparently there was a safety feature that was
supposed to estinguish the light if the shield failed, but the safety
feature failed instead.

At the end of the day, there were complaints of retinal burns,
sunburn, severe headachces and a general sickness from just about all
who attended. Lawsuits were threatened and it became a very expensive
medical incident for the school district.

Prior to this, there was a general ignorance about the importance of
mantaining the lamps in good repair. This event prompted a statewide
review for the procedures in maintaining UV producing lamps, mainly
that they need to be inspected periodically and if the shield is
cracked or missing, the lamp should be removed from service.

Beachcomber

"**THE-RFI-EMI-GUY**" wrote in message
...
I have a couple of those task lights (from China) that had round glass
filters on them. In both cases the filters broke. Is there a source to get
replacements?

TKM wrote:

"snip

To answer your question -- yes, tungsten halogen lamps do emit substantial
amounts of UV and they are perfectly capable of causing skin and eye
damage if you are directly exposed to the light of an unshielded lamp. In
Italy some years ago, users of small halogen task lamps reported sunburn
and other UV-related problems because the lamps were not shielded.

But a piece of glass will filter the UV to minimum levels and the halogen
lamps should be enclosed anyway in case of bulb rupture. You definitely
don't want to experience that in a home office situation.

As others have said, however, there are much better, more efficient and
safer ways to light your office using fluorescent lamps.

Terry McGowan



--
Joe Leikhim K4SAT

They are probably not easily-obtainable through lighting retailers.
However, just go into a local hardware or glass shop and have them cut you a
piece of glass to fit. Ordinary window glass is a fine UV filter. Use a
thicker piece and even tempered glass if you want extra safety.

Terry McGowan

In message , **THE-RFI-EMI-GUY**
writes
I have a couple of those task lights (from China) that had round glass
filters on them. In both cases the filters broke. Is there a source to
get replacements?

First check the cost of complete new lights. If it's the little ones
with the telescopic heads then you may be cheaper and faster just buying
new ones.

--
Clive Mitchell
http:/www.bigclive.com

In alt.engineering.electrical TKM wrote:
|
| "JS" wrote in message
| ...
|I understand that linear tungsten halogen bulbs emit noticeably more
| UV light than general household incandescent bulbs.
|
| Would it be safe to use a 300 Watt tunsten halogen floodlight as a
| good bright light in my home office?
|
| This would be on for approx 8 hours a day. I'm wondering that maybe
| after that sort of exposure the extra UV could become a significant
| adverse effect on eyes & skin.
|
| To answer your question -- yes, tungsten halogen lamps do emit substantial
| amounts of UV and they are perfectly capable of causing skin and eye damage
| if you are directly exposed to the light of an unshielded lamp. In Italy
| some years ago, users of small halogen task lamps reported sunburn and other
| UV-related problems because the lamps were not shielded.
|
| But a piece of glass will filter the UV to minimum levels and the halogen
| lamps should be enclosed anyway in case of bulb rupture. You definitely
| don't want to experience that in a home office situation.
|
| As others have said, however, there are much better, more efficient and
| safer ways to light your office using fluorescent lamps.

I'm looking for a way that results in a uniform continuous spectrum. I have
found that fluorescent does not accomplish that. Also, LED does not, either.
But I think there may be hope in that LEDs are available is lots of different
wavelengths. A mix of a lot of these could come close to the continuous
spectrum.

--
-----------------------------------------------------------------------------
| Phil Howard KA9WGN | http://linuxhomepage.com/ http://ham.org/ |
| (first name) at ipal.net | http://phil.ipal.org/ http://ka9wgn.ham.org/ |
-----------------------------------------------------------------------------

wrote in message
...
In alt.engineering.electrical TKM wrote:
|
| "JS" wrote in message
| ...
|I understand that linear tungsten halogen bulbs emit noticeably more
| UV light than general household incandescent bulbs.
|
| Would it be safe to use a 300 Watt tunsten halogen floodlight as a
| good bright light in my home office?
|
| This would be on for approx 8 hours a day. I'm wondering that maybe
| after that sort of exposure the extra UV could become a significant
| adverse effect on eyes & skin.
|
| To answer your question -- yes, tungsten halogen lamps do emit
substantial
| amounts of UV and they are perfectly capable of causing skin and eye
damage
| if you are directly exposed to the light of an unshielded lamp. In
Italy
| some years ago, users of small halogen task lamps reported sunburn and
other
| UV-related problems because the lamps were not shielded.
|
| But a piece of glass will filter the UV to minimum levels and the
halogen
| lamps should be enclosed anyway in case of bulb rupture. You definitely
| don't want to experience that in a home office situation.
|
| As others have said, however, there are much better, more efficient and
| safer ways to light your office using fluorescent lamps.

I'm looking for a way that results in a uniform continuous spectrum. I
have
found that fluorescent does not accomplish that. Also, LED does not,
either.
But I think there may be hope in that LEDs are available is lots of
different
wavelengths. A mix of a lot of these could come close to the continuous
spectrum.

--
-----------------------------------------------------------------------------
| Phil Howard KA9WGN | http://linuxhomepage.com/
http://ham.org/ |
| (first name) at ipal.net | http://phil.ipal.org/
http://ka9wgn.ham.org/ |
-----------------------------------------------------------------------------

NIST has a current project to build an LED lighting system that has sources
which emit at every 5 nm (I think). Each "color" would be individually
controllable in output. What I didn't understand when I heard about it is
how they expect to find or tune LEDs to the various wavelength bands.

Terry McGowan

"JS" wrote in message
...
On Fri 02 Dec 2005 11:49:37, Victor Roberts
wrote:

Tri-phospher as someone has suggested are totally different to
normal tubes the light is intense enough to make looking at them
very uncomfortable

It's probably not the tri-phosphor but the tube diameter.
Modern T5 lamps, not the old switch-start variety, have a
high surface brightness, and T8 lamps have a higher surface
brightness than T12 lamps, but not so high that most people
will be uncomfortable looking at them. You can also find T12
lamps with tri-phosphor, but they are rather expensive.

I am newbie when it comes to lighting. I have not come across these
T lamp bulbs.

Is there a web page which show pictures or diagrams of the T lamps
(T5, T8, etc) so I can see how they differ from one another.

Google gives me lots of hits but nothing which illutrates or compares
these lights on a single page.

The information is a bit hard to find, but it's out there. The lamp
manufacturers' catalogs are the best way. For example, go to the
fluorescent section of GE's catalog at :
http://www.gelighting.com/na/busines.../lamp_catalog/
Download the fluorescent section and look on the first few pages. T5, T8,
etc. are all shown with their sockets.

Terry McGowan

wrote:

I'm looking for a way that results in a uniform continuous spectrum. I have
found that fluorescent does not accomplish that. Also, LED does not, either.
But I think there may be hope in that LEDs are available is lots of different
wavelengths. A mix of a lot of these could come close to the continuous
spectrum.

Well, yes... but good fluorescents come at least that close. Look for
tubes with a colour rendering index of at least 90. They will be
referred to as "colour 9xx", where the second two digits refer to the
colour temperature. These tubes are usually not as bright as standard
ones, but offer a smoother spectrum.

Off the top of my head, one such range is Osram's "Lumilux Deluxe", at
least in Europe.

Osram and Philips have both recently brought out another range of tubes
with *really* good colour rendering (CRI of 98 or so), but they're
pretty dim for the power input. The Philips one goes by the name of
"Graphica" in Europe, I can't remember what Osram call them. ISTR that
they're only available at a 6000K colour temp or thereabouts, and I
*think* that they may only be in T8.

--
Hello, you've reached the psychiatric hotline. If you are
obsessive and compulsive, please press 1 repeatedly. If you
have multiple personalities, please press 2, 3, 4, and 5.
If you are paranoid, just stay on the line - we know who
you are, and we're on the way.
---------------------------------------------------------------
Simon Waldman, UK email:
---------------------------------------------------------------

"Beachcomber" wrote in message
...

But a piece of glass will filter the UV to minimum levels and the halogen
lamps should be enclosed anyway in case of bulb rupture. You definitely
don't want to experience that in a home office situation.

As others have said, however, there are much better, more efficient and
safer ways to light your office using fluorescent lamps.


We had a case here in Oregon a year or two ago. Seems a large group
of teachers was holding an institute day in the school gym under the
metal halide lamps. Unknown to everyone who attended, one of the UV
shields was broken and the teachers were exposed to high levels of UV
exposure all day. Apparently there was a safety feature that was
supposed to estinguish the light if the shield failed, but the safety
feature failed instead.

At the end of the day, there were complaints of retinal burns,
sunburn, severe headachces and a general sickness from just about all
who attended. Lawsuits were threatened and it became a very expensive
medical incident for the school district.

Prior to this, there was a general ignorance about the importance of
mantaining the lamps in good repair. This event prompted a statewide
review for the procedures in maintaining UV producing lamps, mainly
that they need to be inspected periodically and if the shield is
cracked or missing, the lamp should be removed from service.

Beachcomber

Important information. Such cases have occurred since mercury HID lamps
started to be used for indoor industrial and commercial lighting about 1965.
There have not been massive problems; but since people are injured, any
incident gets attention. The safety device inside the lamp has appeared to
work well (when the outer bulb is broken, outside air causes the safety
device to open the arc tube circuit); but anything can fail to work. I've
always promoted the use of enclosed fixtures for such installations, but
users complained about the higher cost and sometimes the enclosure glass was
broken or not replaced when the fixture was serviced. The maintenance
people must also know enough about the risk to install the lamps with safety
devices as standard lamps will also work in the sockets.

The industry/government has not found a 100% solution to the problem -- most
due, I would say, to lack of knowledge/education and concern about costs.
Unfortunately, it takes a large lawsuit sometimes to get proper attention.

There was a similar problem with exploding metal halide lamps some years
back. The problem was understood, fixes were developed; but no foolproof
solution was implemented. Then the problem got massive attention after a
major lawsuit was lost.

Terry McGowan

"RickR" wrote in message
oups.com...
Underwriters Laboratory requires some sort of sheilding, although in
some cases it is wire mesh rather than glass. (In case of "Non-passive
Failure" - my favorite techno term, thanks to GE.) This covers 99% of
North American instalations and equipment.

This UV scare has been going on for well over ten years. There was an
experiment in Italy where they baked some hairless mice with unsheilded
lamps. Gee, they developed skin problems. The press went wild....
***You get more UV walking to your car than from sitting under halogen
lamps.***

Note to JS: As you noticed lighting is not cut and dried, there are
many options and the best solution depends on the details of your
situation. Energy, quality, dimming, start-up, first costs, space,
style, your age!, type of work....

Good Luck

The problem is usually not the amount of UV coming out of the lamp; it's not
knowing that you are being exposed to it and taking proper precautions.
When people switch on a desk lamp, they don't expect to get "sunburned" from
the light.

Terry McGowan

In sci.engr.lighting TKM wrote:
"Beachcomber" wrote in message
...
Unknown to everyone who attended, one of the UV shields was broken and
the teachers were exposed to high levels of UV exposure all day.

Important information. Such cases have occurred since mercury HID lamps
started to be used for indoor industrial and commercial lighting about
1965. There have not been massive problems; but since people are injured,
any incident gets attention.

On the other end of the visible spectrum, you can get "IR detector" cards
printed with a special ink or dye. You leave it in normal light for a
little while, then shine infrared light on it (like from a TV remote
control) and it lights up. Is anything like this available for UV? I'm
thinking of a small, inexpensive card that could be taped to the wall in
rooms with mercury HID lights, with simple directions like "if the blue
spot printed above turns red, please check the light fixtures."

I'm sure you could build an active circuit for it, but then you have to
get people to change the batteries. If they won't put batteries in smoke
detectors or maintain light fixtures correctly, they probably won't put
batteries in the UV detector. On the other hand, not mantaining the
fixtures might be explained by having to haul things up and down a
ladder, where changing batteries in a device mounted at eye level on the
wall is easier to do.

Matt Roberds

wrote in message
news:ib9mf.27$9G.25@dukeread10...
In sci.engr.lighting TKM wrote:
"Beachcomber" wrote in message
...
Unknown to everyone who attended, one of the UV shields was broken and
the teachers were exposed to high levels of UV exposure all day.

Important information. Such cases have occurred since mercury HID lamps
started to be used for indoor industrial and commercial lighting about
1965. There have not been massive problems; but since people are injured,
any incident gets attention.

On the other end of the visible spectrum, you can get "IR detector" cards
printed with a special ink or dye. You leave it in normal light for a
little while, then shine infrared light on it (like from a TV remote
control) and it lights up. Is anything like this available for UV? I'm
thinking of a small, inexpensive card that could be taped to the wall in
rooms with mercury HID lights, with simple directions like "if the blue
spot printed above turns red, please check the light fixtures."

I'm sure you could build an active circuit for it, but then you have to
get people to change the batteries. If they won't put batteries in smoke
detectors or maintain light fixtures correctly, they probably won't put
batteries in the UV detector. On the other hand, not mantaining the
fixtures might be explained by having to haul things up and down a
ladder, where changing batteries in a device mounted at eye level on the
wall is easier to do.

Matt Roberds

Good idea. I've heard of such detector "dose" cards; but I haven't tried
any. There's a debate building about UV exposure. Some UV is good for
people -- vitamin D, natural sunshine and all that. Some say people don't
get enough these days to ward off rickets, big diseases and even common
colds. Others say UV=skin cancer. End of story. (I'm overstating , of
course :-) But, maybe there are facilities such as hospitals, retirement
homes or even schools in the far north (or south) where UV from sunlight is
zero for much of the year and where we might want to add some UV to lighting
in "sun spaces" or light therapy rooms. If so, a dose card on a person
might ensure that a person gets their proper amount. Enter "Michael F.
Holick" on Google if you want to read about some the pro-UV research.

Terry McGowan

On Fri, 09 Dec 2005 15:33:16 GMT, "TKM"
wrote:


Good idea. I've heard of such detector "dose" cards; but I haven't tried
any. There's a debate building about UV exposure. Some UV is good for
people -- vitamin D, natural sunshine and all that. Some say people don't
get enough these days to ward off rickets, big diseases and even common
colds. Others say UV=skin cancer. End of story. (I'm overstating , of
course :-) But, maybe there are facilities such as hospitals, retirement
homes or even schools in the far north (or south) where UV from sunlight is
zero for much of the year and where we might want to add some UV to lighting
in "sun spaces" or light therapy rooms. If so, a dose card on a person
might ensure that a person gets their proper amount. Enter "Michael F.
Holick" on Google if you want to read about some the pro-UV research.

I assume There's UV and then there's UV, meaning that energy
at some UV wavelengths may indeed be beneficial while energy
at others other may indeed be harmful so we probably need to
be more specific about the radiation than just "UV." One of
Holick's books is titled just "UV" but in the one Holick
article I read he refers to UV-B, which is a bit more
specific. I wonder if Vitamin D production is even more
specific than UV-B.

--
Vic Roberts
http://www.RobertsResearchInc.com
To reply via e-mail:
replace xxx with vdr in the Reply to: address
or use e-mail address listed at the Web site.

This information is provided for educational purposes only.
It may not be used in any publication or posted on any Web
site without written permission.