Unsafe UV from high-power tungsten halogen in office?

[JS]

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.

 

[TKM]

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

 

[dennis@home]

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.

 

[Andrew Gabriel]

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.

 

[Clive Mitchell]

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.

 

[Daniel J. Stern]

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)

 

[Zak]

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

 

[JS]

In message

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]

-- 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..

 

[Clive Mitchell]

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.

 

[Jeff]

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

 

[[email protected]]

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!

 

[Victor Roberts]

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
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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.

 

[Daniel J. Stern]

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.

 

[JS]

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.

 

[Andrew Gabriel]

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.)

 

[Victor Roberts]

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.

 

[Beachcomber]

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

 

[TKM]

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?

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

 

[Clive Mitchell]

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.