Hi,

I have a Lutron dimmer that dims a 100w (4 x 25w) light fixture in a
bathroom. I noticed that one of the 25w bulbs was out and that the
dimmer does not dim any more. My question is can a bulb burning out
cause a sufficiently high current transient / short to burn out a
dimmer?

I read in this news group that bulbs blowing can be a reason that a
dimmer fails. Is this true?

best, Mike.

On Jul 24, 4:42 am, hobbes wrote:
Hi,

I have a Lutron dimmer that dims a 100w (4 x 25w) light fixture in a
bathroom. I noticed that one of the 25w bulbs was out and that the
dimmer does not dim any more. My question is can a bulb burning out
cause a sufficiently high current transient / short to burn out a
dimmer?

I read in this news group that bulbs blowing can be a reason that a
dimmer fails. Is this true?

best, Mike.

Some of the clear bulbs hold the filament delicately with wires that
can short together and burn the triac out.

It is true and happens frequently. Also fixtures with candelabra sockets
often develope minor short circuits in the socket, just a momentary pop, not
enough to trip the breaker, but enough to take out a dimmer



"hobbes" wrote in message
ps.com...
Hi,

I have a Lutron dimmer that dims a 100w (4 x 25w) light fixture in a
bathroom. I noticed that one of the 25w bulbs was out and that the
dimmer does not dim any more. My question is can a bulb burning out
cause a sufficiently high current transient / short to burn out a
dimmer?

I read in this news group that bulbs blowing can be a reason that a
dimmer fails. Is this true?

best, Mike.

"RBM" rbm2(remove wrote in message
...
It is true and happens frequently. Also fixtures with candelabra sockets
often develope minor short circuits in the socket, just a momentary pop,
not enough to trip the breaker, but enough to take out a dimmer



"hobbes" wrote in message
ps.com...
Hi,

I have a Lutron dimmer that dims a 100w (4 x 25w) light fixture in a
bathroom. I noticed that one of the 25w bulbs was out and that the
dimmer does not dim any more. My question is can a bulb burning out
cause a sufficiently high current transient / short to burn out a
dimmer?

I read in this news group that bulbs blowing can be a reason that a
dimmer fails. Is this true?

best, Mike.


Huh. So that is maybe what happened to the dimmer in the dining 'room' area
of the kitchen in my cookie cutter. It has one of those pug-ugly chandelier
things that uses those damn candle-base bulbs. (as does the other big
ceiling fixture, non-dimmed, also a piece of junk.) Dimmer still works as a
switch, so haven't bothered to replace it yet. Been looking off and on for
replacement ceiling fixtures for the kitchen, but none of them in the stores
seem to have normal bulb sockets. And the current one has one neat feature-
a downward-facing flood bulb in the center, to light up the table enough to
read newspapers at.

aem sends....

According to aemeijers :

Huh. So that is maybe what happened to the dimmer in the dining 'room' area
of the kitchen in my cookie cutter. It has one of those pug-ugly chandelier
things that uses those damn candle-base bulbs. (as does the other big
ceiling fixture, non-dimmed, also a piece of junk.) Dimmer still works as a
switch, so haven't bothered to replace it yet. Been looking off and on for
replacement ceiling fixtures for the kitchen, but none of them in the stores
seem to have normal bulb sockets. And the current one has one neat feature-
a downward-facing flood bulb in the center, to light up the table enough to
read newspapers at.

Yup. Semiconductor triacs act like _extremely_ fast fuses. The
mere whiff of a short lasting a few tens of milliseconds can fry one
long before a regular fuse or breaker notices anything awry.
--
Chris Lewis,

Age and Treachery will Triumph over Youth and Skill
It's not just anyone who gets a Starship Cruiser class named after them.

On Tue, 24 Jul 2007 11:51:36 GMT, "aemeijers"
wrote:


Huh. So that is maybe what happened to the dimmer in the dining 'room' area
of the kitchen in my cookie cutter. It has one of those pug-ugly chandelier

I always thought the phrase was plug-ugly, but your words make more
sense. Anyone know more about this?

things that uses those damn candle-base bulbs. (as does the other big
ceiling fixture, non-dimmed, also a piece of junk.) Dimmer still works as a
switch, so haven't bothered to replace it yet. Been looking off and on for
replacement ceiling fixtures for the kitchen, but none of them in the stores
seem to have normal bulb sockets. And the current one has one neat feature-
a downward-facing flood bulb in the center, to light up the table enough to
read newspapers at.

aem sends....

hobbes wrote:
Hi,

I have a Lutron dimmer that dims a 100w (4 x 25w) light fixture in a
bathroom. I noticed that one of the 25w bulbs was out and that the
dimmer does not dim any more. My question is can a bulb burning out
cause a sufficiently high current transient / short to burn out a
dimmer?

I read in this news group that bulbs blowing can be a reason that a
dimmer fails. Is this true?

best, Mike.


Yes, what occasionally happens when a bulb burns out is that a phenomena
called a "tungsten arc" occurs. The filament break develops an arc
between the broken ends which melts those ends and vaporizes some
tungsten. The arc continues, melting more tungsten and shortening the
remaining filament ends and the current increases as more of the
filaments melt and the density of the vaporized tungsten increases.

It all happens faster than you can say Jill Robinson, usually
accompanied by a bright white flash just as you "turn on the lights".

The current will sometimes surge high enough to blow a panel fuse or
breaker, or as in your case, to fry the triac in a dimmer.

Good quality light bulbs used to have special thin wire "fuses" as part
of their construction which were just thick enough to let the bulbs be
turned on and run but would "blow out" if the bulb developed a tungsten
arc. I don't know if that's still the case.

When you are replacing the dimmer, go to Rat Shack and pick yourself up
an inline 3AG fuse holder and a few 2 amp 3AG fuses. Wire the fuseholder
in series with the hot feed to the dimmer (it should fit inside the
dimmer box) and you'll be pretty well be protected against a future
burnout. You may have to replace a burned out fuse, but the dimmer
should be OK.

That's just what I did with the four table lamps in our home which are
fitted with "touch dimmers". After the second dimmer blew I added 2 amp
fuses to all of them. I've probably replaced six fuses in the last five
years, but all the dimmers are still alive and well.

HTH,

Jeff
--
Jeffry Wisnia
(W1BSV + Brass Rat '57 EE)
The speed of light is 1.8*10^12 furlongs per fortnight.

According to mm :
On Tue, 24 Jul 2007 11:51:36 GMT, "aemeijers"
wrote:


Huh. So that is maybe what happened to the dimmer in the dining 'room' area
of the kitchen in my cookie cutter. It has one of those pug-ugly chandelier

I always thought the phrase was plug-ugly, but your words make more
sense. Anyone know more about this?

I've normally heard "plug-ugly", but if your dog is ugly enough to
serve as an example... ;-)
--
Chris Lewis,

Age and Treachery will Triumph over Youth and Skill
It's not just anyone who gets a Starship Cruiser class named after them.

According to Jeff Wisnia :

When you are replacing the dimmer, go to Rat Shack and pick yourself up
an inline 3AG fuse holder and a few 2 amp 3AG fuses. Wire the fuseholder
in series with the hot feed to the dimmer (it should fit inside the
dimmer box) and you'll be pretty well be protected against a future
burnout. You may have to replace a burned out fuse, but the dimmer
should be OK.

That's just what I did with the four table lamps in our home which are
fitted with "touch dimmers". After the second dimmer blew I added 2 amp
fuses to all of them. I've probably replaced six fuses in the last five
years, but all the dimmers are still alive and well.

I find it hard to imagine that a fuse would blow fast enough to
protect a triac. But, if it works...

Make sure you get fast-blo.
--
Chris Lewis,

Age and Treachery will Triumph over Youth and Skill
It's not just anyone who gets a Starship Cruiser class named after them.

Lutron has replaced all of the dimmer switched that I purchased (from HD)
for free. In fact, they did it twice because they were apprently defective
(the 2nd round of switches I got unsolicited). You may get the same
courtesy by contacting them:

Mailing Address:
Customer Service
Lutron Electronics Company Co., Inc.
7200 Suter Road
Coopersburg, PA 18036


Phone Number: 1-(888) LUTRON1

Fax Number: (610) 282-3090

E-Mail Address: E-Mail:


"hobbes" wrote in message
ps.com...
Hi,

I have a Lutron dimmer that dims a 100w (4 x 25w) light fixture in a
bathroom. I noticed that one of the 25w bulbs was out and that the
dimmer does not dim any more. My question is can a bulb burning out
cause a sufficiently high current transient / short to burn out a
dimmer?

I read in this news group that bulbs blowing can be a reason that a
dimmer fails. Is this true?

best, Mike.

Chris Lewis wrote:
According to Jeff Wisnia :


When you are replacing the dimmer, go to Rat Shack and pick yourself up
an inline 3AG fuse holder and a few 2 amp 3AG fuses. Wire the fuseholder
in series with the hot feed to the dimmer (it should fit inside the
dimmer box) and you'll be pretty well be protected against a future
burnout. You may have to replace a burned out fuse, but the dimmer
should be OK.



That's just what I did with the four table lamps in our home which are
fitted with "touch dimmers". After the second dimmer blew I added 2 amp
fuses to all of them. I've probably replaced six fuses in the last five
years, but all the dimmers are still alive and well.


I find it hard to imagine that a fuse would blow fast enough to
protect a triac. But, if it works...

Make sure you get fast-blo.

Thanks, I realized too late that I forgot to mention that.

Not to be pedagogical, but I sized the fuses for my lamps by looking up
the specs of the triacs in my lamps' touch dimmers, the ones which were
punching through, and found on their maximum I^2*t rating. (eye squared
times tea)

Then I looked on Buss' website and found that the blowing energy (also
expressed as I^2*t) of their 3AG 2A fast blow fuses was somewhat less
than that of the triac, so I figured it should work.

And work it has....I use two 75 watt bulbs in a "Y" adaptor in each of
those table lamps cause the two are cheaper two purchase than one 150
watter in most places, plus when one bulb dies I still can get light to
see my way around from the other one, assuming it didn't expire with one
of those tungsten arc blasts and take out the fuse. I think I probably
have three or four "normal" bulb burnouts for every one which takes a
fuse along with it.

And some people accuse me of being a geek who "gilds turds"....Wonder
why that is....G

Jeff

--
Jeffry Wisnia
(W1BSV + Brass Rat '57 EE)
The speed of light is 1.8*10^12 furlongs per fortnight.

In om, hobbes wrote:
Hi,

I have a Lutron dimmer that dims a 100w (4 x 25w) light fixture in a
bathroom. I noticed that one of the 25w bulbs was out and that the
dimmer does not dim any more. My question is can a bulb burning out
cause a sufficiently high current transient / short to burn out a
dimmer?

I read in this news group that bulbs blowing can be a reason that a
dimmer fails. Is this true?

A bulb blowing, especially the usual burnout with a bright blue flash,
can take out the dimmer.

The bright blue flash is a "burnout arc", which can briefly draw
something like 100 amps or more for a few milliseconds. The dimmer may be
made as cheaply as possible, and could only "usually" as opposed to really
reliably survive the current surge of a burnout arc.

I have also heard of complaints of a few lightbulbs lacking fusible
links in their necks. Those are supposed to blow if a burnout arc draws a
really bad current surge. In extreme cases, I have heard of bulbs without
fusible links failing badly with the glass bulb popping off the base. My
guess is that the wires violently vaporize adjacent glue/cement due to an
extreme current surge drawn by a burnout arc.

Lightbulbs of "Big 3" brands (GE, Sylvania, Philips) probably have fewer
issues in this area. Store brand lightbulbs of "usual regular shape and
size" and 25, 40, 60, 75 or 100 watts and same hour life expectancy
figures and same lumen light output figures as "Big 3 brand" ones are "Big
3" ones with the only difference being the brand or lack thereof printed
on the top of the bulb.

Lowest prices I have seen for "standard" "Big 3" lightbulbs: At Lowes.

Another idea: Use compact fluorescents and do without the dimmer. Four
7-watt spirals will outshine four 25-watt incandescents, and a 25 watt
incandescent dimmed to the point of consuming 7 watts will produce about
1/4 or less the light of a 7 watt nightlight. If you never or hardly
ever need less light than that and dim only for energy conservation
purposes, go for compact fluorescents if you don't need dimming.

Now another idea: Compact fluorescents often do not do well in
bathrooms often used for short trips - unless they are cold cathode! And
cold cathode ones are dimmable. They are somewhat less efficient than the
usual hot cathode ones, but still a lot more efficient than incandescents.
Online lightbulb sellers sell ones up to 8 watts, which are about as
bright as 25 watt incandescents. They are rated to last 25,000 hours and
do not suffer extra wear from starting, and are even rated for
flashing/blinking duty. What mainly tends to go wrong with those is that
they fade as the phosphor gets worn out over the years, otherwise they
fail from breakage or the electronics blowing from an especially bad power
surge that blows electronic products.

Still another idea: If there is a need for dim light as well as bright
light, the most energy-efficient option is to have separate light sources
for those. (Though dimmable compact fluorescents are a close second and
quite convenient.) The dim-light source could be a nightlight having a
built-in switch and the traditionally incandescent bulb replaced by a 3
watt cold cathode compact fluorescent, such as the 3-watt N:Vision one
available at Home Depot. If you like less light than that, LED
nightlights do well there with usually around 1 watt of power consumption.

- Don Klipstein )

I weird thing about triacs...they are opposed diacs...if you use them
with a DC current...once you turn them on
(gate current)...you can't turn them off.
You have to open the circuit.
They can be used as solid state relays.
(Opposed or back-to-back is really not the right term, triacs are
parallel wired with a common gate diacs.)

Hope this makes sense...I am in my 60s...and if the mind is like the
body...

Jeff Wisnia wrote:

....
And work it has....I use two 75 watt bulbs in a "Y" adaptor in each of
those table lamps cause the two are cheaper two purchase than one 150
watter in most places,
....
Two 75 watt bulbs produces a lot less light and are a lot less efficient
than one 150 watt bulb. You will pay more for the electricity:

75 watt GE "standard" 1190 lumens
150 watt GE "standard" 2850 lumens

That's 20% more light for the same power or 20% more efficient.
Also, you would probably find the quality of light more
desirable from the 150 watt bulb (higher color temperature).

Over the estimated 750 hour lifetime, you will use 112.5 KwH.
If you are fortunate enough to pay only 10 cents per KwH,
thats $22.50 of electricity.

Also note, that when you use a dimmer, although you use less
power, the bulb gets much less efficient.

M Q wrote:
Jeff Wisnia wrote:

...

And work it has....I use two 75 watt bulbs in a "Y" adaptor in each of
those table lamps cause the two are cheaper two purchase than one 150
watter in most places,

...
Two 75 watt bulbs produces a lot less light and are a lot less efficient
than one 150 watt bulb. You will pay more for the electricity:

75 watt GE "standard" 1190 lumens
150 watt GE "standard" 2850 lumens

That's 20% more light for the same power or 20% more efficient.
Also, you would probably find the quality of light more
desirable from the 150 watt bulb (higher color temperature).

Over the estimated 750 hour lifetime, you will use 112.5 KwH.
If you are fortunate enough to pay only 10 cents per KwH,
thats $22.50 of electricity.

Also note, that when you use a dimmer, although you use less
power, the bulb gets much less efficient.


Points well taken. I hadn't thought that one through.

I may just buy a few 150 watt bulbs this weekend, the additional lumens
will probably make it easier for my aging eyes to read stuff.

Thanks,

Jeff

--
Jeffry Wisnia
(W1BSV + Brass Rat '57 EE)
The speed of light is 1.98*10^14 fathoms per fortnight.

According to :
I weird thing about triacs...they are opposed diacs...if you use them
with a DC current...once you turn them on
(gate current)...you can't turn them off.

Triacs are sorta opposed SCRs, not diacs. Diacs are two lead devices,
effectively back to back zener diodes. No current until the voltage
gets to the zener (diode reverse breakover) voltage. Unlike a zener,
the breakover is in both directions. With zener diode, it breakovers
one way, and the other way it acts as a normal diode and conducts
at .6V.

Diacs were commonly used in triac dimmer cicuits to provide firing
control to the gate, but now I think they do without them.

Right - to turn of a SCR or triac, the voltage across the main terminals
has to drop (close) to zero. With household AC, of course, that
happens 120 times per second.

Tho, I seem to recall something violent you could do with the gate
to get an SCR to shut off without zeroing the voltage. Or at
least a buddy claimed it would cut off if you shorted the gate
to the "nearby" main terminal.
--
Chris Lewis,

Age and Treachery will Triumph over Youth and Skill
It's not just anyone who gets a Starship Cruiser class named after them.

On Jul 25, 12:19 am, (Chris Lewis) wrote:
According to :

I weird thing about triacs...they are opposed diacs...if you use them
with a DC current...once you turn them on
(gate current)...you can't turn them off.

Triacs are sorta opposed SCRs, not diacs. Diacs are two lead devices,
effectively back to back zener diodes. No current until the voltage
gets to the zener (diode reverse breakover) voltage. Unlike a zener,
the breakover is in both directions. With zener diode, it breakovers
one way, and the other way it acts as a normal diode and conducts
at .6V.

Diacs were commonly used in triac dimmer cicuits to provide firing
control to the gate, but now I think they do without them.

Right - to turn of a SCR or triac, the voltage across the main terminals
has to drop (close) to zero. With household AC, of course, that
happens 120 times per second.

Tho, I seem to recall something violent you could do with the gate
to get an SCR to shut off without zeroing the voltage. Or at
least a buddy claimed it would cut off if you shorted the gate
to the "nearby" main terminal.
--
Chris Lewis,

Age and Treachery will Triumph over Youth and Skill
It's not just anyone who gets a Starship Cruiser class named after them.

Thanks for straightening me out! Of course, when you said, SCR, I went
"doh!"

Don Klipstein wrote:


Now another idea: Compact fluorescents often do not do well in
bathrooms often used for short trips - unless they are cold cathode! And
cold cathode ones are dimmable.

Are all dimable CFLs cold cathode?

Roughly what happens to CFL efficiency as they are dimmed?

Dimable linear tube fluorescent balasts, IIRC, have a maintained hot
lead to power the filaments. What happens to efficiency as they are dimmed?

--------------
You should write a book. In effect, you probably have.

--
bud--

Jeff Wisnia wrote:
Chris Lewis wrote:
According to Jeff Wisnia :


When you are replacing the dimmer, go to Rat Shack and pick yourself
up an inline 3AG fuse holder and a few 2 amp 3AG fuses. Wire the
fuseholder in series with the hot feed to the dimmer (it should fit
inside the dimmer box) and you'll be pretty well be protected against
a future burnout. You may have to replace a burned out fuse, but the
dimmer should be OK.



That's just what I did with the four table lamps in our home which
are fitted with "touch dimmers". After the second dimmer blew I added
2 amp fuses to all of them. I've probably replaced six fuses in the
last five years, but all the dimmers are still alive and well.


I find it hard to imagine that a fuse would blow fast enough to
protect a triac. But, if it works...

Make sure you get fast-blo.

Thanks, I realized too late that I forgot to mention that.

Not to be pedagogical, but I sized the fuses for my lamps by looking up
the specs of the triacs in my lamps' touch dimmers, the ones which were
punching through, and found on their maximum I^2*t rating. (eye squared
times tea)

Then I looked on Buss' website and found that the blowing energy (also
expressed as I^2*t) of their 3AG 2A fast blow fuses was somewhat less
than that of the triac, so I figured it should work.


I am sincerely genuinely impressed. The application is specific to the
triac and type of Buss fuse used, but has a good chance of working in
general.

Nitpicking - also check the fuse voltage ratings, and fuseholder ratings.

There may be more room to install a fuse at the light fixture.


And some people accuse me of being a geek who "gilds turds"....Wonder
why that is....G


Doesn't everyone guild turds?

--
bud--

On Wed, 25 Jul 2007 12:23:07 -0500, bud--
wrote:

Jeff Wisnia wrote:
Chris Lewis wrote:
According to Jeff Wisnia :


When you are replacing the dimmer, go to Rat Shack and pick yourself
up an inline 3AG fuse holder and a few 2 amp 3AG fuses. Wire the
fuseholder in series with the hot feed to the dimmer (it should fit
inside the dimmer box) and you'll be pretty well be protected against
a future burnout. You may have to replace a burned out fuse, but the
dimmer should be OK.



That's just what I did with the four table lamps in our home which
are fitted with "touch dimmers". After the second dimmer blew I added
2 amp fuses to all of them. I've probably replaced six fuses in the
last five years, but all the dimmers are still alive and well.


I find it hard to imagine that a fuse would blow fast enough to
protect a triac. But, if it works...

Make sure you get fast-blo.

Thanks, I realized too late that I forgot to mention that.

Not to be pedagogical, but I sized the fuses for my lamps by looking up
the specs of the triacs in my lamps' touch dimmers, the ones which were
punching through, and found on their maximum I^2*t rating. (eye squared
times tea)

Then I looked on Buss' website and found that the blowing energy (also
expressed as I^2*t) of their 3AG 2A fast blow fuses was somewhat less
than that of the triac, so I figured it should work.


I am sincerely genuinely impressed. The application is specific to the
triac and type of Buss fuse used, but has a good chance of working in
general.

Nitpicking - also check the fuse voltage ratings, and fuseholder ratings.

There may be more room to install a fuse at the light fixture.

Right, but in the dimmer, there might be room for a glass fuse without
a fuseholder. Either one with pigtails (wires soldered to the ends)
or small endcaps that are barely bigger than the metal ends of the
glass fuses. I don't know what Jeff actually used.

According to mm :

On Wed, 25 Jul 2007 12:23:07 -0500, bud--
wrote:

There may be more room to install a fuse at the light fixture.

Right, but in the dimmer, there might be room for a glass fuse without
a fuseholder. Either one with pigtails (wires soldered to the ends)
or small endcaps that are barely bigger than the metal ends of the
glass fuses. I don't know what Jeff actually used.

There may be enough room for it, but not after you've taped it
so that they don't short against the dimmer box. "Inline" fuse
holders (like the automotive variety) are plastic and don't
expose any metal bits. But they are kinda bulky, as are dimmers.
Wouldn't lay odds you could install one in anything but the deepest
receptacle box.
--
Chris Lewis,

Age and Treachery will Triumph over Youth and Skill
It's not just anyone who gets a Starship Cruiser class named after them.

In article , bud-- wrote:
Don Klipstein wrote:

Now another idea: Compact fluorescents often do not do well in
bathrooms often used for short trips - unless they are cold cathode! And
cold cathode ones are dimmable.

Are all dimable CFLs cold cathode?

No. The dimmable version of Philips SLS 23 is hot cathode.

Roughly what happens to CFL efficiency as they are dimmed?

Dimable linear tube fluorescent balasts, IIRC, have a maintained hot
lead to power the filaments. What happens to efficiency as they are dimmed?

I imagine that there is some loss of efficiency when dimming a dimmable
hot cathode CFL, since I suspect the ballast provides some means to keep
the electrodes hot. I am not sure this is the case.

I expect any CFL will operate less efficiently when dimmed, but
generally only slightly less efficiently when dimmed unless the dimming is
very severe. I expect ballast losses to be a higher percentage of input
power during dimming. Incandescents lose effciency much more than
fluorescents do when dimmed.

- Don Klipstein )

"Chris Lewis" wrote in message
...
According to aemeijers :

Huh. So that is maybe what happened to the dimmer in the dining 'room'
area
of the kitchen in my cookie cutter. It has one of those pug-ugly
chandelier
things that uses those damn candle-base bulbs. (as does the other big
ceiling fixture, non-dimmed, also a piece of junk.) Dimmer still works as
a
switch, so haven't bothered to replace it yet. Been looking off and on
for
replacement ceiling fixtures for the kitchen, but none of them in the
stores
seem to have normal bulb sockets. And the current one has one neat
feature-
a downward-facing flood bulb in the center, to light up the table enough
to
read newspapers at.

Yup. Semiconductor triacs act like _extremely_ fast fuses. The
mere whiff of a short lasting a few tens of milliseconds can fry one
long before a regular fuse or breaker notices anything awry.
Mebbe I'll just replace it with a decora single pole, then, and just install
the new dimmer I bought right before I sell it. Being old, I never dim
anyway.

aem sends...

"Jeff Wisnia" wrote in message
...
hobbes wrote:
Hi,

I have a Lutron dimmer that dims a 100w (4 x 25w) light fixture in a
bathroom. I noticed that one of the 25w bulbs was out and that the
dimmer does not dim any more. My question is can a bulb burning out
cause a sufficiently high current transient / short to burn out a
dimmer?

I read in this news group that bulbs blowing can be a reason that a
dimmer fails. Is this true?

best, Mike.


Yes, what occasionally happens when a bulb burns out is that a phenomena
called a "tungsten arc" occurs. The filament break develops an arc between
the broken ends which melts those ends and vaporizes some tungsten. The
arc continues, melting more tungsten and shortening the remaining filament
ends and the current increases as more of the filaments melt and the
density of the vaporized tungsten increases.

It all happens faster than you can say Jill Robinson, usually accompanied
by a bright white flash just as you "turn on the lights".

That sounds about right- those junk candle bulbs seem to go out with a bang.

aem sends....

mm wrote:
On Wed, 25 Jul 2007 12:23:07 -0500, bud--
wrote:


Jeff Wisnia wrote:

Chris Lewis wrote:

According to Jeff Wisnia :



When you are replacing the dimmer, go to Rat Shack and pick yourself
up an inline 3AG fuse holder and a few 2 amp 3AG fuses. Wire the
fuseholder in series with the hot feed to the dimmer (it should fit
inside the dimmer box) and you'll be pretty well be protected against
a future burnout. You may have to replace a burned out fuse, but the
dimmer should be OK.




That's just what I did with the four table lamps in our home which
are fitted with "touch dimmers". After the second dimmer blew I added
2 amp fuses to all of them. I've probably replaced six fuses in the
last five years, but all the dimmers are still alive and well.


I find it hard to imagine that a fuse would blow fast enough to
protect a triac. But, if it works...

Make sure you get fast-blo.

Thanks, I realized too late that I forgot to mention that.

Not to be pedagogical, but I sized the fuses for my lamps by looking up
the specs of the triacs in my lamps' touch dimmers, the ones which were
punching through, and found on their maximum I^2*t rating. (eye squared
times tea)

Then I looked on Buss' website and found that the blowing energy (also
expressed as I^2*t) of their 3AG 2A fast blow fuses was somewhat less
than that of the triac, so I figured it should work.


I am sincerely genuinely impressed. The application is specific to the
triac and type of Buss fuse used, but has a good chance of working in
general.

Nitpicking - also check the fuse voltage ratings, and fuseholder ratings.

There may be more room to install a fuse at the light fixture.


Right, but in the dimmer, there might be room for a glass fuse without
a fuseholder. Either one with pigtails (wires soldered to the ends)
or small endcaps that are barely bigger than the metal ends of the
glass fuses. I don't know what Jeff actually used.


Well, as long as you sort of asked....

All four of the table lamps with touch dimmers in our home are Asian
styles with "full metal jacket" brass bodies. I installed the touch
dimmers in all of them myself, inside the lamp bases.

When the time came to add those fuses I Installed panel mount 3AG fuse
holders through holes I drilled in the side of the lamps bases, near
where the lamp cords exited.

Things being what they are, every few years we get a new cleaning person
and it sometime takes a little time for them to get used to those touch
switches. So, after the first few housecleanings (we're absent when
those happen) I'l maybe find the original manual switch on a lamp's bulb
socket turned to the OFF position, and once a lamp wouldn't turn on when
I touched it because the lady thought the fuseholder cap was a switch
and twisted it so that it sprang out enough to open the circuit. G

Jeff

--
Jeffry Wisnia
(W1BSV + Brass Rat '57 EE)
The speed of light is 1.8*10^12 furlongs per fortnight.

Jeff Wisnia wrote:

M Q wrote:

Jeff Wisnia wrote:

...

And work it has....I use two 75 watt bulbs in a "Y" adaptor in each
of those table lamps cause the two are cheaper two purchase than one
150 watter in most places,


...
Two 75 watt bulbs produces a lot less light and are a lot less efficient
than one 150 watt bulb. You will pay more for the electricity:

75 watt GE "standard" 1190 lumens
150 watt GE "standard" 2850 lumens

That's 20% more light for the same power or 20% more efficient.
Also, you would probably find the quality of light more
desirable from the 150 watt bulb (higher color temperature).

Over the estimated 750 hour lifetime, you will use 112.5 KwH.
If you are fortunate enough to pay only 10 cents per KwH,
thats $22.50 of electricity.

Also note, that when you use a dimmer, although you use less
power, the bulb gets much less efficient.


Points well taken. I hadn't thought that one through.

I may just buy a few 150 watt bulbs this weekend, the additional lumens
will probably make it easier for my aging eyes to read stuff.

Thanks,

Jeff


Well, I followed through and bought some 150 watt bulbs yesterday. While
I was at the store looking at the lumen ratings of frosted incandescents
I noticed that the 150 watt output of a "three way" 50-100-150 watt bulb
was also considerably lower than that of the plain 150 watter.

I replaced the "Y" adaptor and its two 75 watt bulbs in just one of our
two living room table lamps with a 150 watt bulb.

the results were pretty dramatic, the lamp with the 150 watt bulb was
noticably brighter, so I put a 150 watter in the other one too.

Now I need someone to understand why the single 150 watt incandescent
puts out 20 percent more lumens than the pair of 75 watt bulbs. (Are you
reading Don Klipstein?) I'm guessing it might have something to do with
more thermal energy being tossed away through four filament supports
than through two, or something like that.

I'll be kicking myself for a while over not thinking about the lumen
output when I decided to install those "Y" adaptors with pairs of 75
watt bulbs.

As my mother-in law used to say, "Jeff, for a smart guy, every once in a
while you do stupid pretty good."

Thasnks again,

Jeff
--
Jeffry Wisnia
(W1BSV + Brass Rat '57 EE)
The speed of light is 1.98*10^14 fathoms per fortnight.

Jeff Wisnia wrote:

....
Well, I followed through and bought some 150 watt bulbs yesterday. While
I was at the store looking at the lumen ratings of frosted incandescents
I noticed that the 150 watt output of a "three way" 50-100-150 watt bulb
was also considerably lower than that of the plain 150 watter.
Yes, a "3-way" is just a 50 W and a 100 W in the same globe.

I replaced the "Y" adaptor and its two 75 watt bulbs in just one of our
two living room table lamps with a 150 watt bulb.

the results were pretty dramatic, the lamp with the 150 watt bulb was
noticably brighter, so I put a 150 watter in the other one too.

Now I need someone to understand why the single 150 watt incandescent
puts out 20 percent more lumens than the pair of 75 watt bulbs. (Are you
reading Don Klipstein?) I'm guessing it might have something to do with
more thermal energy being tossed away through four filament supports
than through two, or something like that.

I can give you a partial answer. The filaments in higher wattage
bulbs are designed to run at a higher temperature. At the higher
temperatures, more of the radiated energy is in the visible light
portion of the spectrum (see http://en.wikipedia.org/wiki/Black_body )
(however still only around 3-5%). Why don't we just run all
bulbs hotter? That dramatically decreases the lifetime of the
filament. Why can we get away with running higher wattage
filaments hooter than lower wattage ones? That's the part that I
don't know.

P.S. Halogen is a technology for increasing the lifetime of the
filament, allowing you to run it hotter.


I'll be kicking myself for a while over not thinking about the lumen
output when I decided to install those "Y" adaptors with pairs of 75
watt bulbs.

Most people are unaware of that, including many energy conservation
advocacy organization that encourage people to use lower wattage
bulbs. Also, it is getting harder to find light output
figures on many types of bulbs.

M Q wrote:



Jeff Wisnia wrote:

...

Well, I followed through and bought some 150 watt bulbs yesterday.
While I was at the store looking at the lumen ratings of frosted
incandescents I noticed that the 150 watt output of a "three way"
50-100-150 watt bulb was also considerably lower than that of the
plain 150 watter.

Yes, a "3-way" is just a 50 W and a 100 W in the same globe.


I replaced the "Y" adaptor and its two 75 watt bulbs in just one of
our two living room table lamps with a 150 watt bulb.

the results were pretty dramatic, the lamp with the 150 watt bulb was
noticably brighter, so I put a 150 watter in the other one too.

Now I need someone to understand why the single 150 watt incandescent
puts out 20 percent more lumens than the pair of 75 watt bulbs. (Are
you reading Don Klipstein?) I'm guessing it might have something to do
with more thermal energy being tossed away through four filament
supports than through two, or something like that.


I can give you a partial answer. The filaments in higher wattage
bulbs are designed to run at a higher temperature. At the higher
temperatures, more of the radiated energy is in the visible light
portion of the spectrum (see http://en.wikipedia.org/wiki/Black_body )
(however still only around 3-5%). Why don't we just run all
bulbs hotter? That dramatically decreases the lifetime of the
filament. Why can we get away with running higher wattage
filaments hooter than lower wattage ones? That's the part that I
don't know.


Maybe another reason is because the bases of both bulbs are the same
diameter but the 75 watt bulb is physically smaller than the 150 watt
one. That puts its filament closer to its the base which makes the base
obscures a larger solid angle in the total sphere of radiation, thus
blocking a greater percentage of the visible light?

Jeff

snipped

--
Jeffry Wisnia
(W1BSV + Brass Rat '57 EE)
The speed of light is 1.8*10^12 furlongs per fortnight.

replying to hobbes, Marty wrote:
Mike: I am looking for burnt/fried Maestro-style Lutron dimmers for parts. I
will pay the shipping. TIA

--
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