Strange CFL Failure Mode
See: http://repairfaq.cis.upenn.edu/Misc/cflhole1.jpg
This is a ~1 mm hole in the glass near one of the filaments. Something got hot enough for the glass to melt, and after that, as they say, the rest was history. :) I've seen this on 3 CFLs in 3 different lamps/fixtures. There are no known problems that could account for such nasty behavior. They were all high mileage, so perhaps the filament at that end of the lamp opened resulting in the discharge going to one post, near the glass, or something. :) The CFLs were all from GE but I don't know if they are of the same ballast/lamp design. Comments welcome. -- sam | Sci.Electronics.Repair FAQ: http://www.repairfaq.org/ Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/ +Lasers | Sam's Laser FAQ: http://www.repairfaq.org/sam/lasersam.htm | Mirror Sites: http://www.repairfaq.org/REPAIR/F_mirror.html Important: Anything sent to the email address in the message header above is ignored unless my full name AND either lasers or electronics is included in the subject line. Or, you can contact me via the Feedback Form in the FAQs. |
Strange CFL Failure Mode
"Samuel M. Goldwasser" wrote in message ... See: http://repairfaq.cis.upenn.edu/Misc/cflhole1.jpg This is a ~1 mm hole in the glass near one of the filaments. Something got hot enough for the glass to melt, and after that, as they say, the rest was history. :) I've seen this on 3 CFLs in 3 different lamps/fixtures. There are no known problems that could account for such nasty behavior. They were all high mileage, so perhaps the filament at that end of the lamp opened resulting in the discharge going to one post, near the glass, or something. :) The CFLs were all from GE but I don't know if they are of the same ballast/lamp design. Comments welcome. -- sam | Sci.Electronics.Repair FAQ: http://www.repairfaq.org/ Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/ +Lasers | Sam's Laser FAQ: http://www.repairfaq.org/sam/lasersam.htm | Mirror Sites: http://www.repairfaq.org/REPAIR/F_mirror.html Important: Anything sent to the email address in the message header above is ignored unless my full name AND either lasers or electronics is included in the subject line. Or, you can contact me via the Feedback Form in the FAQs. Sounds like a hot blob of tungsten or emission material was ejected from the lamp's cathode. An arc could certainly do that. It's common in incandescent filament lamps that arc upon failure; but I wouldn't have thought that there's enough energy available in a low-wattage CFL to do it. What were the wattages of the lamps? But, there were some arcing problems with T5 and some T8 lamps a few years ago when operated on instant-start ballasts. At end-of-life, the cathodes failed and an arc started chewing away at the cathode mount wires. Things got hot, lamps cracked and lamp holders were charred. This all resulted in the development of ballasts that shut the lamp off if an arc was sensed so as to avoid the mess of cleaning up broken lamps and the concern that sputtering lamps, smoke and the smell of overheated plastic caused. Terry McGowan |
Strange CFL Failure Mode
"Samuel M. Goldwasser" wrote in message ... See: http://repairfaq.cis.upenn.edu/Misc/cflhole1.jpg This is a ~1 mm hole in the glass near one of the filaments. Something got hot enough for the glass to melt, and after that, as they say, the rest was history. :) I've seen this on 3 CFLs in 3 different lamps/fixtures. There are no known problems that could account for such nasty behavior. They were all high mileage, so perhaps the filament at that end of the lamp opened resulting in the discharge going to one post, near the glass, or something. :) The CFLs were all from GE but I don't know if they are of the same ballast/lamp design. Comments welcome. -- sam | Sci.Electronics.Repair FAQ: http://www.repairfaq.org/ Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/ +Lasers | Sam's Laser FAQ: http://www.repairfaq.org/sam/lasersam.htm | Mirror Sites: http://www.repairfaq.org/REPAIR/F_mirror.html Hmmm. Another 'dangerous' aspect of these dreadful devices then. If they don't send you blind, or provoke epileptic fits, they'll get you by venting their mercury vapour !! :-) Arfa |
Strange CFL Failure Mode
On Jul 15, 5:01*pm, "Arfa Daily" wrote:
"Samuel M. Goldwasser" wrote in ... See:http://repairfaq.cis.upenn.edu/Misc/cflhole1.jpg This is a ~1 mm hole in the glass near one of the filaments. Something got hot enough for the glass to melt, and after that, as they say, the rest was history. :) I've seen this on 3 CFLs in 3 different lamps/fixtures. *There are no known problems that could account for such nasty behavior. *They were all high mileage, so perhaps the filament at that end of the lamp opened resulting in the discharge going to one post, near the glass, or something. :) The CFLs were all from GE but I don't know if they are of the same ballast/lamp design. Comments welcome. -- * *sam | Sci.Electronics.Repair FAQ:http://www.repairfaq.org/ Repair | Main Table of Contents:http://www.repairfaq.org/REPAIR/ +Lasers | Sam's Laser FAQ:http://www.repairfaq.org/sam/lasersam.htm * * * *| Mirror Sites:http://www.repairfaq.org/REPAIR/F_mirror.html Hmmm. Another 'dangerous' aspect of these dreadful devices then. If they don't send you blind, or provoke epileptic fits, they'll get you by venting their mercury vapour !! * *:-) Arfa Yep, soon they'll be considered as dangerous as incandescent lamps that burn fingers, start fires, explode, send molten glass and tungsten shooting about and electrocute those who try to change the bulb. ;-) Terry |
Strange CFL Failure Mode
"Terry" wrote in message ... On Jul 15, 5:01 pm, "Arfa Daily" wrote: "Samuel M. Goldwasser" wrote in ... See:http://repairfaq.cis.upenn.edu/Misc/cflhole1.jpg This is a ~1 mm hole in the glass near one of the filaments. Something got hot enough for the glass to melt, and after that, as they say, the rest was history. :) I've seen this on 3 CFLs in 3 different lamps/fixtures. There are no known problems that could account for such nasty behavior. They were all high mileage, so perhaps the filament at that end of the lamp opened resulting in the discharge going to one post, near the glass, or something. :) The CFLs were all from GE but I don't know if they are of the same ballast/lamp design. Comments welcome. -- sam | Sci.Electronics.Repair FAQ:http://www.repairfaq.org/ Repair | Main Table of Contents:http://www.repairfaq.org/REPAIR/ +Lasers | Sam's Laser FAQ:http://www.repairfaq.org/sam/lasersam.htm | Mirror Sites:http://www.repairfaq.org/REPAIR/F_mirror.html Hmmm. Another 'dangerous' aspect of these dreadful devices then. If they don't send you blind, or provoke epileptic fits, they'll get you by venting their mercury vapour !! :-) Arfa Yep, soon they'll be considered as dangerous as incandescent lamps that burn fingers, start fires, explode, send molten glass and tungsten shooting about and electrocute those who try to change the bulb. ;-) Terry My my, Terry. You do live an interesting and dangerous life ... During my many years of shuffling around on this little orb of ours, I don't think I have ever had a domestic incandescent light bulb start a fire, explode, reach a temperature where the glss could become molten, shoot molten tungsten at me, or try to electrocute me (how does that one work then ??). I would have to admit to having scorched (rather than burnt) my fingers a time or two, but that was down to me employing stupid tactics for handling them .... d:-) Arfa |
Strange CFL Failure Mode
In article , "Arfa Daily" wrote:
"Terry" wrote in message ... On Jul 15, 5:01 pm, "Arfa Daily" wrote: "Samuel M. Goldwasser" wrote in ... See:http://repairfaq.cis.upenn.edu/Misc/cflhole1.jpg This is a ~1 mm hole in the glass near one of the filaments. Something got hot enough for the glass to melt, and after that, as they say, the rest was history. :) I've seen this on 3 CFLs in 3 different lamps/fixtures. There are no known problems that could account for such nasty behavior. They were all high mileage, so perhaps the filament at that end of the lamp opened resulting in the discharge going to one post, near the glass, or something. :) The CFLs were all from GE but I don't know if they are of the same ballast/lamp design. Comments welcome. -- sam | Sci.Electronics.Repair FAQ:http://www.repairfaq.org/ Repair | Main Table of Contents:http://www.repairfaq.org/REPAIR/ +Lasers | Sam's Laser FAQ:http://www.repairfaq.org/sam/lasersam.htm | Mirror Sites:http://www.repairfaq.org/REPAIR/F_mirror.html Hmmm. Another 'dangerous' aspect of these dreadful devices then. If they don't send you blind, or provoke epileptic fits, they'll get you by venting their mercury vapour !! :-) Arfa Yep, soon they'll be considered as dangerous as incandescent lamps that burn fingers, start fires, explode, send molten glass and tungsten shooting about and electrocute those who try to change the bulb. ;-) Terry My my, Terry. You do live an interesting and dangerous life ... During my many years of shuffling around on this little orb of ours, I don't think I have ever had a domestic incandescent light bulb start a fire, explode, reach a temperature where the glss could become molten, shoot molten tungsten at me, or try to electrocute me (how does that one work then ??). I would have to admit to having scorched (rather than burnt) my fingers a time or two, but that was down to me employing stupid tactics for handling them .... d:-) Arfa No fires here yet. I just had one infantile failure out of a batch of 6 I bought. 9 watts at 40 watts effective halogen brightness. I don't think being outside was a problem even thought its not for outside. These are flood or spots. What I have found, I can get moe light out of a 1.5 watt LED spot vs a 9-12 watt CFL. The reason being, CFL's are poor choice for spots due to the poor beam width. A lot of CFL's say, no dimmers or relays. The same for LED's most of the time. I can't really figure the relay bit. greg |
Strange CFL Failure Mode
Hi!
This is a ~1 mm hole in the glass near one of the filaments. Something got hot enough for the glass to melt, and after that, as they say, the rest was history. :) Comments welcome. I've seen the effect on some very narrow GE tubes in use with conventional overhead fixtures. When the tubes die, they oftentimes crack a ring in the glass or blow a slightly larger hole in it at either edge. This makes changing them "fun". I'm not sure if it is specific to the tubes or not. The GE tubes have not proven long lived. I started dating them after some tubes from a different maker with the wrong color temperature were purchased and installed during late 2005. All of the misordered tubes are still going strong, nine hours a day in most locations. The oldest GE tubes date from 2007, and there are very few left. All fixtures are identical. William |
Strange CFL Failure Mode
GregS wrote:
In article , "Arfa Daily" wrote: "Terry" wrote in message ... On Jul 15, 5:01 pm, "Arfa Daily" wrote: "Samuel M. Goldwasser" wrote in ... See:http://repairfaq.cis.upenn.edu/Misc/cflhole1.jpg This is a ~1 mm hole in the glass near one of the filaments. Something got hot enough for the glass to melt, and after that, as they say, the rest was history. :) I've seen this on 3 CFLs in 3 different lamps/fixtures. There are no known problems that could account for such nasty behavior. They were all high mileage, so perhaps the filament at that end of the lamp opened resulting in the discharge going to one post, near the glass, or something. :) The CFLs were all from GE but I don't know if they are of the same ballast/lamp design. Comments welcome. -- sam | Sci.Electronics.Repair FAQ:http://www.repairfaq.org/ Repair | Main Table of Contents:http://www.repairfaq.org/REPAIR/ +Lasers | Sam's Laser FAQ:http://www.repairfaq.org/sam/lasersam.htm | Mirror Sites:http://www.repairfaq.org/REPAIR/F_mirror.html Hmmm. Another 'dangerous' aspect of these dreadful devices then. If they don't send you blind, or provoke epileptic fits, they'll get you by venting their mercury vapour !! :-) Arfa Yep, soon they'll be considered as dangerous as incandescent lamps that burn fingers, start fires, explode, send molten glass and tungsten shooting about and electrocute those who try to change the bulb. ;-) Terry My my, Terry. You do live an interesting and dangerous life ... During my many years of shuffling around on this little orb of ours, I don't think I have ever had a domestic incandescent light bulb start a fire, explode, reach a temperature where the glss could become molten, shoot molten tungsten at me, or try to electrocute me (how does that one work then ??). I would have to admit to having scorched (rather than burnt) my fingers a time or two, but that was down to me employing stupid tactics for handling them .... d:-) Arfa No fires here yet. I just had one infantile failure out of a batch of 6 I bought. 9 watts at 40 watts effective halogen brightness. I don't think being outside was a problem even thought its not for outside. These are flood or spots. What I have found, I can get moe light out of a 1.5 watt LED spot vs a 9-12 watt CFL. The reason being, CFL's are poor choice for spots due to the poor beam width. A lot of CFL's say, no dimmers or relays. The same for LED's most of the time. I can't really figure the relay bit. Likely "solid state" relays. Some X-10 devices, for example, are solid state and may not work. A mechanical relay would work fine. -- bud-- |
Strange CFL Failure Mode
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Strange CFL Failure Mode
"Arfa Daily" wrote in message ... "Terry" wrote in message ... On Jul 15, 5:01 pm, "Arfa Daily" wrote: "Samuel M. Goldwasser" wrote in ... See:http://repairfaq.cis.upenn.edu/Misc/cflhole1.jpg This is a ~1 mm hole in the glass near one of the filaments. Something got hot enough for the glass to melt, and after that, as they say, the rest was history. :) I've seen this on 3 CFLs in 3 different lamps/fixtures. There are no known problems that could account for such nasty behavior. They were all high mileage, so perhaps the filament at that end of the lamp opened resulting in the discharge going to one post, near the glass, or something. :) The CFLs were all from GE but I don't know if they are of the same ballast/lamp design. Comments welcome. -- sam | Sci.Electronics.Repair FAQ:http://www.repairfaq.org/ Repair | Main Table of Contents:http://www.repairfaq.org/REPAIR/ +Lasers | Sam's Laser FAQ:http://www.repairfaq.org/sam/lasersam.htm | Mirror Sites:http://www.repairfaq.org/REPAIR/F_mirror.html Hmmm. Another 'dangerous' aspect of these dreadful devices then. If they don't send you blind, or provoke epileptic fits, they'll get you by venting their mercury vapour !! :-) Arfa Yep, soon they'll be considered as dangerous as incandescent lamps that burn fingers, start fires, explode, send molten glass and tungsten shooting about and electrocute those who try to change the bulb. ;-) Terry My my, Terry. You do live an interesting and dangerous life ... During my many years of shuffling around on this little orb of ours, I don't think I have ever had a domestic incandescent light bulb start a fire, explode, reach a temperature where the glss could become molten, shoot molten tungsten at me, or try to electrocute me (how does that one work then ??). I would have to admit to having scorched (rather than burnt) my fingers a time or two, but that was down to me employing stupid tactics for handling them ... d:-) Arfa All that stuff has happened usually because (full disclosure) I treated the lamp rather badly. A drop or two of water on a hot 100 watt GLS lamp, for example, is sure to cause damage and, probably, fireworks. I was electrically shocked when I tried to put a 60-watt lamp into a portable lamp socket with the socket turned on and didn't realize it was an old portable which didn't have a polarized plug. It's easy to touch the threaded part of the base when you reach under the shade with the lamp and try to position it in the socket. Terry McGowan |
Strange CFL Failure Mode
"TKM" wrote in message ... "Arfa Daily" wrote in message ... "Terry" wrote in message ... On Jul 15, 5:01 pm, "Arfa Daily" wrote: "Samuel M. Goldwasser" wrote in ... See:http://repairfaq.cis.upenn.edu/Misc/cflhole1.jpg This is a ~1 mm hole in the glass near one of the filaments. Something got hot enough for the glass to melt, and after that, as they say, the rest was history. :) I've seen this on 3 CFLs in 3 different lamps/fixtures. There are no known problems that could account for such nasty behavior. They were all high mileage, so perhaps the filament at that end of the lamp opened resulting in the discharge going to one post, near the glass, or something. :) The CFLs were all from GE but I don't know if they are of the same ballast/lamp design. Comments welcome. -- sam | Sci.Electronics.Repair FAQ:http://www.repairfaq.org/ Repair | Main Table of Contents:http://www.repairfaq.org/REPAIR/ +Lasers | Sam's Laser FAQ:http://www.repairfaq.org/sam/lasersam.htm | Mirror Sites:http://www.repairfaq.org/REPAIR/F_mirror.html Hmmm. Another 'dangerous' aspect of these dreadful devices then. If they don't send you blind, or provoke epileptic fits, they'll get you by venting their mercury vapour !! :-) Arfa Yep, soon they'll be considered as dangerous as incandescent lamps that burn fingers, start fires, explode, send molten glass and tungsten shooting about and electrocute those who try to change the bulb. ;-) Terry My my, Terry. You do live an interesting and dangerous life ... During my many years of shuffling around on this little orb of ours, I don't think I have ever had a domestic incandescent light bulb start a fire, explode, reach a temperature where the glss could become molten, shoot molten tungsten at me, or try to electrocute me (how does that one work then ??). I would have to admit to having scorched (rather than burnt) my fingers a time or two, but that was down to me employing stupid tactics for handling them ... d:-) Arfa All that stuff has happened usually because (full disclosure) I treated the lamp rather badly. A drop or two of water on a hot 100 watt GLS lamp, for example, is sure to cause damage and, probably, fireworks. I was electrically shocked when I tried to put a 60-watt lamp into a portable lamp socket with the socket turned on and didn't realize it was an old portable which didn't have a polarized plug. It's easy to touch the threaded part of the base when you reach under the shade with the lamp and try to position it in the socket. Terry McGowan Ah ! That all makes more sense now. That last 'problem' can't occur in the UK as the outer part of the bayonet type bulb holders we normally use here, is not part of the electrical connection to the bulb, and is either sheilded with a bakelite type material anyway, or grounded if not. That said, we are starting to see more lamps with standard ES holders - allbeit shielded - and a lot more with MES holders that would be quite hard to stick your finger into to make contact with the centre pin. The wall plugs are not reversible like some U.S. ones are, but that of course doesn't stop people putting re-wirable ones on, backwards ... :-\ Arfa |
Strange CFL Failure Mode
On Thu, 16 Jul 2009 17:38:16 +0100, Arfa Daily wrote:
I don't think I have ever had a domestic incandescent light bulb [...] This commentary reminded me of a quite-unpleasant experience in late boyhood. Apparently, an incandescent bulb in the cellar had a film of moisture on it (it had just been turned on). When I touched the glass, I got a nasty shock; damp concrete floor, etc. The socket must have been wired with its threaded shell to the hot side of the line. Not the bulb's fault, of course. Btw, hot glass is conductive, just about certain. Regards, -- Nicabod =+= Waltham, Mass. |
Strange CFL Failure Mode
"Nicholas Bodley" wrote in message ... On Thu, 16 Jul 2009 17:38:16 +0100, Arfa Daily wrote: I don't think I have ever had a domestic incandescent light bulb [...] This commentary reminded me of a quite-unpleasant experience in late boyhood. Apparently, an incandescent bulb in the cellar had a film of moisture on it (it had just been turned on). When I touched the glass, I got a nasty shock; damp concrete floor, etc. The socket must have been wired with its threaded shell to the hot side of the line. Not the bulb's fault, of course. Btw, hot glass is conductive, just about certain. Regards, -- Nicabod =+= Waltham, Mass. Well, if it is, and I rather suspect it's not, the amount of conductivity is very small. I work a lot with power valves (tubes) which run hot enough to take your fingerprints off in decimals of a second, and these often have as much as 800 volts on the anode pins. Some years back, I used to work with high power audio distribution amplifiers on a community radio network. The (foot high internally assembled with nuts and bolts) tubes on these 7 foot tall amplifier cabinets, often used to run so hot that the glass was actually glowing dull red. I have seen dents in the glass where the vacuum has started sucking on areas that have got *so* hot that they have softened. The HT supply on these beasts was about 2.5Kv as I recall, derived from mercury vapour rectifier tubes. Given these facts, if the glass had much conductivity when hot, you would pretty soon be into having leakage paths between the pins, and to the grounded retainer metalwork, that holds the devices into their sockets, wouldn't you ? Arfa |
Strange CFL Failure Mode
On Tue, 21 Jul 2009 19:40:49 +0100, "Arfa Daily"
wrote: "Nicholas Bodley" wrote in message ... On Thu, 16 Jul 2009 17:38:16 +0100, Arfa Daily wrote: I don't think I have ever had a domestic incandescent light bulb [...] This commentary reminded me of a quite-unpleasant experience in late boyhood. Apparently, an incandescent bulb in the cellar had a film of moisture on it (it had just been turned on). When I touched the glass, I got a nasty shock; damp concrete floor, etc. The socket must have been wired with its threaded shell to the hot side of the line. Not the bulb's fault, of course. Btw, hot glass is conductive, just about certain. Regards, -- Nicabod =+= Waltham, Mass. Well, if it is, and I rather suspect it's not, the amount of conductivity is very small. I work a lot with power valves (tubes) which run hot enough to take your fingerprints off in decimals of a second, and these often have as much as 800 volts on the anode pins. Some years back, I used to work with high power audio distribution amplifiers on a community radio network. The (foot high internally assembled with nuts and bolts) tubes on these 7 foot tall amplifier cabinets, often used to run so hot that the glass was actually glowing dull red. I have seen dents in the glass where the vacuum has started sucking on areas that have got *so* hot that they have softened. The HT supply on these beasts was about 2.5Kv as I recall, derived from mercury vapour rectifier tubes. Given these facts, if the glass had much conductivity when hot, you would pretty soon be into having leakage paths between the pins, and to the grounded retainer metalwork, that holds the devices into their sockets, wouldn't you ? Arfa Ordinary incandescent lamps are made from soda lime glass, which has enough conductivity at 100C to maintain a low frequency (DC or 60Hz) discharge in T12 fluorescent lamps using electrodes on the outside of the bulb. The place where the wires are sealed in an incandescent lamp (the pinch seal) is made from lead glass, that has much lower conductivity than soda lime glass. Vacuum tubes are usually made from borosilicate glass (Pyrex(R)) that has even lower conductivity than lead glass, and much lower than soda lime glass. -- 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. |
Strange CFL Failure Mode
"Victor Roberts" wrote in message ... On Tue, 21 Jul 2009 19:40:49 +0100, "Arfa Daily" wrote: "Nicholas Bodley" wrote in message ... On Thu, 16 Jul 2009 17:38:16 +0100, Arfa Daily wrote: I don't think I have ever had a domestic incandescent light bulb [...] This commentary reminded me of a quite-unpleasant experience in late boyhood. Apparently, an incandescent bulb in the cellar had a film of moisture on it (it had just been turned on). When I touched the glass, I got a nasty shock; damp concrete floor, etc. The socket must have been wired with its threaded shell to the hot side of the line. Not the bulb's fault, of course. Btw, hot glass is conductive, just about certain. Regards, -- Nicabod =+= Waltham, Mass. Well, if it is, and I rather suspect it's not, the amount of conductivity is very small. I work a lot with power valves (tubes) which run hot enough to take your fingerprints off in decimals of a second, and these often have as much as 800 volts on the anode pins. Some years back, I used to work with high power audio distribution amplifiers on a community radio network. The (foot high internally assembled with nuts and bolts) tubes on these 7 foot tall amplifier cabinets, often used to run so hot that the glass was actually glowing dull red. I have seen dents in the glass where the vacuum has started sucking on areas that have got *so* hot that they have softened. The HT supply on these beasts was about 2.5Kv as I recall, derived from mercury vapour rectifier tubes. Given these facts, if the glass had much conductivity when hot, you would pretty soon be into having leakage paths between the pins, and to the grounded retainer metalwork, that holds the devices into their sockets, wouldn't you ? Arfa Ordinary incandescent lamps are made from soda lime glass, which has enough conductivity at 100C to maintain a low frequency (DC or 60Hz) discharge in T12 fluorescent lamps using electrodes on the outside of the bulb. The place where the wires are sealed in an incandescent lamp (the pinch seal) is made from lead glass, that has much lower conductivity than soda lime glass. Vacuum tubes are usually made from borosilicate glass (Pyrex(R)) that has even lower conductivity than lead glass, and much lower than soda lime glass. -- Vic Roberts http://www.RobertsResearchInc.com Thanks for that Vic. Always good to learn from someone 'in the know' on the more specialist aspects of electronics. Arfa |
Strange CFL Failure Mode
In , Arfa Daily wrote in part:
The (foot high internally assembled with nuts and bolts) tubes on these 7 foot tall amplifier cabinets, often used to run so hot that the glass was actually glowing dull red. I have seen dents in the glass where the vacuum has started sucking on areas that have got *so* hot that they have softened. The HT supply on these beasts was about 2.5Kv as I recall, derived from mercury vapour rectifier tubes. Given these facts, if the glass had much conductivity when hot, you would pretty soon be into having leakage paths between the pins, and to the grounded retainer metalwork, that holds the devices into their sockets, wouldn't you ? The glass around the pins is not as hot as the glass on the sides and the top. Meanwhile, even soda lime glass is not that much of a conductor at 200-300 degrees C. I have heard of HID lamps requiring any metal supports to be isolated, to avoid problems with electrolysis of the glass bulb. I imagine this problem involves amounts of current low enough to not be a shock hazard. On the other hand, I have seen glass heated to the point of being soft conduct impressive amounts of current (several milliamps, possibly more) at a few kilovolts. I do not know what kind of glass was involved - either soda lime or a cheaper flint glass, probably soda lime. - Don Klipstein ) |
Strange CFL Failure Mode
On Thu, 23 Jul 2009 22:14:05 +0000 (UTC),
(Don Klipstein) wrote: In , Arfa Daily wrote in part: The (foot high internally assembled with nuts and bolts) tubes on these 7 foot tall amplifier cabinets, often used to run so hot that the glass was actually glowing dull red. I have seen dents in the glass where the vacuum has started sucking on areas that have got *so* hot that they have softened. The HT supply on these beasts was about 2.5Kv as I recall, derived from mercury vapour rectifier tubes. Given these facts, if the glass had much conductivity when hot, you would pretty soon be into having leakage paths between the pins, and to the grounded retainer metalwork, that holds the devices into their sockets, wouldn't you ? The glass around the pins is not as hot as the glass on the sides and the top. Meanwhile, even soda lime glass is not that much of a conductor at 200-300 degrees C. I have heard of HID lamps requiring any metal supports to be isolated, to avoid problems with electrolysis of the glass bulb. I imagine this problem involves amounts of current low enough to not be a shock hazard. On the other hand, I have seen glass heated to the point of being soft conduct impressive amounts of current (several milliamps, possibly more) at a few kilovolts. I do not know what kind of glass was involved - either soda lime or a cheaper flint glass, probably soda lime. - Don Klipstein ) There's an interesting demonstration that can be done with a rod of soda lime glass. If it is connected to a source with the appropriate voltage output and current capability, and then heated, it will conduct enough current to sustain the temperature required for conduction when the external heating supply is removed. I'm sorry to say I don't know how much voltage is required to do this on any particular size rod of soda lime glass. -- 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. |
Strange CFL Failure Mode
On Tue, 21 Jul 2009 19:40:49 +0100, "Arfa Daily"
wrote: "Nicholas Bodley" wrote in message ... On Thu, 16 Jul 2009 17:38:16 +0100, Arfa Daily wrote: I don't think I have ever had a domestic incandescent light bulb [...] This commentary reminded me of a quite-unpleasant experience in late boyhood. Apparently, an incandescent bulb in the cellar had a film of moisture on it (it had just been turned on). When I touched the glass, I got a nasty shock; damp concrete floor, etc. The socket must have been wired with its threaded shell to the hot side of the line. Not the bulb's fault, of course. Btw, hot glass is conductive, just about certain. Regards, -- Nicabod =+= Waltham, Mass. Well, if it is, and I rather suspect it's not, the amount of conductivity is very small. I work a lot with power valves (tubes) which run hot enough to take your fingerprints off in decimals of a second, and these often have as much as 800 volts on the anode pins. Some years back, I used to work with high power audio distribution amplifiers on a community radio network. The (foot high internally assembled with nuts and bolts) tubes on these 7 foot tall amplifier cabinets, often used to run so hot that the glass was actually glowing dull red. I have seen dents in the glass where the vacuum has started sucking on areas that have got *so* hot that they have softened. The HT supply on these beasts was about 2.5Kv as I recall, derived from mercury vapour rectifier tubes. Given these facts, if the glass had much conductivity when hot, you would pretty soon be into having leakage paths between the pins, and to the grounded retainer metalwork, that holds the devices into their sockets, wouldn't you ? Arfa Any links to these giants? -- Boris |
Strange CFL Failure Mode
"Boris Mohar" wrote in message ... On Tue, 21 Jul 2009 19:40:49 +0100, "Arfa Daily" wrote: "Nicholas Bodley" wrote in message ... On Thu, 16 Jul 2009 17:38:16 +0100, Arfa Daily wrote: I don't think I have ever had a domestic incandescent light bulb [...] This commentary reminded me of a quite-unpleasant experience in late boyhood. Apparently, an incandescent bulb in the cellar had a film of moisture on it (it had just been turned on). When I touched the glass, I got a nasty shock; damp concrete floor, etc. The socket must have been wired with its threaded shell to the hot side of the line. Not the bulb's fault, of course. Btw, hot glass is conductive, just about certain. Regards, -- Nicabod =+= Waltham, Mass. Well, if it is, and I rather suspect it's not, the amount of conductivity is very small. I work a lot with power valves (tubes) which run hot enough to take your fingerprints off in decimals of a second, and these often have as much as 800 volts on the anode pins. Some years back, I used to work with high power audio distribution amplifiers on a community radio network. The (foot high internally assembled with nuts and bolts) tubes on these 7 foot tall amplifier cabinets, often used to run so hot that the glass was actually glowing dull red. I have seen dents in the glass where the vacuum has started sucking on areas that have got *so* hot that they have softened. The HT supply on these beasts was about 2.5Kv as I recall, derived from mercury vapour rectifier tubes. Given these facts, if the glass had much conductivity when hot, you would pretty soon be into having leakage paths between the pins, and to the grounded retainer metalwork, that holds the devices into their sockets, wouldn't you ? Arfa Any links to these giants? -- Boris Friend of mine still has a couple I believe. I'll get him to check the numbers on them (it's been a long while ago, and I can't remember any more). I'll also see if I can get a coupla piccies of them. The amps in question fed a radio relay network around large areas of the town. They were located in the cellar of a house in the centre of town. Above them on the ground floor, was our workshop, which was always lovely and warm in the winter :-) On the first floor, above that, was the control room. The radio receivers were located there, and a large patchboard, where the distribution lines were routed, using the big old three pin Bulgin plugs and sockets. There was also a desk console, with an array of meters, which measured 'load'. They were actually measuring audio current going out on the lines. We used to have fun on a slow Saturday afternoon, when there was no no bosses about, by waiting for an important set of sports results, and then either pulling the plug on a whole area, or switching in the spare receiver, which we had pre-tuned to an offshore pirate radio station. Then wait for the phone to start ringing off the hook down in the office, where some poor part time lady would be located to take any service calls ... :-)) Arfa |
Strange CFL Failure Mode
In article ,
Victor Roberts writes: Ordinary incandescent lamps are made from soda lime glass, which has enough conductivity at 100C to maintain a low frequency (DC or 60Hz) discharge in T12 fluorescent lamps using electrodes on the outside of the bulb. The place where the wires are sealed in an incandescent lamp (the pinch seal) is made from lead glass, that has much lower conductivity than soda lime glass. Vacuum tubes are usually made from borosilicate glass (Pyrex(R)) that has even lower conductivity than lead glass, and much lower than soda lime glass. Thanks, interesting. However note that Pyrex(R) no longer implies any particular glass type, and in particular, it's no longer borosilicate glass in the US. -- Andrew Gabriel [email address is not usable -- followup in the newsgroup] |
Strange CFL Failure Mode
On 24 Jul 2009 08:43:43 GMT,
(Andrew Gabriel) wrote: In article , Victor Roberts writes: Ordinary incandescent lamps are made from soda lime glass, which has enough conductivity at 100C to maintain a low frequency (DC or 60Hz) discharge in T12 fluorescent lamps using electrodes on the outside of the bulb. The place where the wires are sealed in an incandescent lamp (the pinch seal) is made from lead glass, that has much lower conductivity than soda lime glass. Vacuum tubes are usually made from borosilicate glass (Pyrex(R)) that has even lower conductivity than lead glass, and much lower than soda lime glass. Thanks, interesting. However note that Pyrex(R) no longer implies any particular glass type, and in particular, it's no longer borosilicate glass in the US. Pyrex seems to still be a registered trademark of Corning, at least in the US, though I do see that the use of the Pyrex name has expanded well beyond borosilicate glass, for example, to metal cookware. -- 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. |
Strange CFL Failure Mode
"Victor Roberts" wrote in message ... On Thu, 23 Jul 2009 22:14:05 +0000 (UTC), (Don Klipstein) wrote: In , Arfa Daily wrote in part: The (foot high internally assembled with nuts and bolts) tubes on these 7 foot tall amplifier cabinets, often used to run so hot that the glass was actually glowing dull red. I have seen dents in the glass where the vacuum has started sucking on areas that have got *so* hot that they have softened. The HT supply on these beasts was about 2.5Kv as I recall, derived from mercury vapour rectifier tubes. Given these facts, if the glass had much conductivity when hot, you would pretty soon be into having leakage paths between the pins, and to the grounded retainer metalwork, that holds the devices into their sockets, wouldn't you ? The glass around the pins is not as hot as the glass on the sides and the top. Meanwhile, even soda lime glass is not that much of a conductor at 200-300 degrees C. I have heard of HID lamps requiring any metal supports to be isolated, to avoid problems with electrolysis of the glass bulb. I imagine this problem involves amounts of current low enough to not be a shock hazard. On the other hand, I have seen glass heated to the point of being soft conduct impressive amounts of current (several milliamps, possibly more) at a few kilovolts. I do not know what kind of glass was involved - either soda lime or a cheaper flint glass, probably soda lime. - Don Klipstein ) There's an interesting demonstration that can be done with a rod of soda lime glass. If it is connected to a source with the appropriate voltage output and current capability, and then heated, it will conduct enough current to sustain the temperature required for conduction when the external heating supply is removed. I'm sorry to say I don't know how much voltage is required to do this on any particular size rod of soda lime glass. -- 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. Fascinating. I wonder if there are glass furnaces that switch from gas to electrical glass-conductive heating once the glass is molten. Terry McGowan Terry McGowan |
Strange CFL Failure Mode
On Fri, 24 Jul 2009 12:14:06 -0400, "TKM"
wrote: "Victor Roberts" wrote in message .. . On Thu, 23 Jul 2009 22:14:05 +0000 (UTC), (Don Klipstein) wrote: In , Arfa Daily wrote in part: The (foot high internally assembled with nuts and bolts) tubes on these 7 foot tall amplifier cabinets, often used to run so hot that the glass was actually glowing dull red. I have seen dents in the glass where the vacuum has started sucking on areas that have got *so* hot that they have softened. The HT supply on these beasts was about 2.5Kv as I recall, derived from mercury vapour rectifier tubes. Given these facts, if the glass had much conductivity when hot, you would pretty soon be into having leakage paths between the pins, and to the grounded retainer metalwork, that holds the devices into their sockets, wouldn't you ? The glass around the pins is not as hot as the glass on the sides and the top. Meanwhile, even soda lime glass is not that much of a conductor at 200-300 degrees C. I have heard of HID lamps requiring any metal supports to be isolated, to avoid problems with electrolysis of the glass bulb. I imagine this problem involves amounts of current low enough to not be a shock hazard. On the other hand, I have seen glass heated to the point of being soft conduct impressive amounts of current (several milliamps, possibly more) at a few kilovolts. I do not know what kind of glass was involved - either soda lime or a cheaper flint glass, probably soda lime. - Don Klipstein ) There's an interesting demonstration that can be done with a rod of soda lime glass. If it is connected to a source with the appropriate voltage output and current capability, and then heated, it will conduct enough current to sustain the temperature required for conduction when the external heating supply is removed. I'm sorry to say I don't know how much voltage is required to do this on any particular size rod of soda lime glass. -- 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. Fascinating. I wonder if there are glass furnaces that switch from gas to electrical glass-conductive heating once the glass is molten. Terry McGowan Terry McGowan I had forgotten about that, but the answer is yes. See US 2,280,101, issued April 21, 1942. I've put a copy on my web site: http://www.robertsresearchinc.com/Papers/US2280101.pdf -- 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. |
Strange CFL Failure Mode
In , Victor Roberts wrote:
On Thu, 23 Jul 2009 22:14:05 +0000 (UTC), (Don Klipstein) wrote: SNIP to edit for space Meanwhile, even soda lime glass is not that much of a conductor at 200-300 degrees C. I have heard of HID lamps requiring any metal supports to be isolated, to avoid problems with electrolysis of the glass bulb. I imagine this problem involves amounts of current low enough to not be a shock hazard. On the other hand, I have seen glass heated to the point of being soft conduct impressive amounts of current (several milliamps, possibly more) at a few kilovolts. I do not know what kind of glass was involved - either soda lime or a cheaper flint glass, probably soda lime. - Don Klipstein ) There's an interesting demonstration that can be done with a rod of soda lime glass. If it is connected to a source with the appropriate voltage output and current capability, and then heated, it will conduct enough current to sustain the temperature required for conduction when the external heating supply is removed. I'm sorry to say I don't know how much voltage is required to do this on any particular size rod of soda lime glass. I do remember seeing somewhere on the Web how to melt a soda bottle (or was it a beer bottle?) in a microwave oven. The glass bottle to be melted required a hot spot pre-heated with a "blowtorch" / "propane torch" or the like, to temperature that I visually estimate to be in the 800's degrees C. It appears to me that soda lime glass that hot achieves conductivity and resistivity suitable for being sufficiently receptive for heating by a microwave oven. ========================= Disclaimer: I sense that this is adventurous usage of a microwave oven, attempt to do such only at your own risk of damaging your microwave oven or burning down the real estate that such microwave oven is in/on and injuring/killing life forms in/on such real estate including loved-ones, friends and pets by starting a fire. - Don Klipstein ) |
Strange CFL Failure Mode
In , Victor Roberts wrote:
On 24 Jul 2009 08:43:43 GMT, (Andrew Gabriel) wrote: In article , Victor Roberts writes: Ordinary incandescent lamps are made from soda lime glass, which has enough conductivity at 100C to maintain a low frequency (DC or 60Hz) discharge in T12 fluorescent lamps using electrodes on the outside of the bulb. The place where the wires are sealed in an incandescent lamp (the pinch seal) is made from lead glass, that has much lower conductivity than soda lime glass. Vacuum tubes are usually made from borosilicate glass (Pyrex(R)) that has even lower conductivity than lead glass, and much lower than soda lime glass. Thanks, interesting. However note that Pyrex(R) no longer implies any particular glass type, and in particular, it's no longer borosilicate glass in the US. Pyrex seems to still be a registered trademark of Corning, at least in the US, though I do see that the use of the Pyrex name has expanded well beyond borosilicate glass, for example, to metal cookware. This makes me wonder if the name "Pyrex" "expanded" to glass types other than borosilicate, as opposed to merely being "expanded" to non-glass items. - Don Klipstein ) |
Strange CFL Failure Mode
In article ,
(Don Klipstein) writes: In , Victor Roberts wrote: On 24 Jul 2009 08:43:43 GMT, (Andrew Gabriel) wrote: However note that Pyrex(R) no longer implies any particular glass type, and in particular, it's no longer borosilicate glass in the US. Pyrex seems to still be a registered trademark of Corning, at least in the US, though I do see that the use of the Pyrex name has expanded well beyond borosilicate glass, for example, to metal cookware. This makes me wonder if the name "Pyrex" "expanded" to glass types other than borosilicate, as opposed to merely being "expanded" to non-glass items. In the US, Pyrex is currently tempered sola lime glass: http://www.pyrexware.com/thetruthaboutpyrex/manu.htm A factory in Europe also licenses the name, and apparently produces borosilicate glass. Pyrex is now simply used as a respected brand name, still owned by Corning, but licensed out to whoever wants to use the name. It doesn't imply glass, or any particular type of glass. Corning no longer make anything under the Pyrex name themselves. -- Andrew Gabriel [email address is not usable -- followup in the newsgroup] |
Strange CFL Failure Mode
On Thu, 16 Jul 2009 17:38:16 +0100, "Arfa Daily"
put finger to keyboard and composed: During my many years of shuffling around on this little orb of ours, I don't think I have ever had a domestic incandescent light bulb start a fire, explode, I had a bad batch of incandescent light bulbs where the glass separated from the base and fell, or was ejected, onto the floor. - Franc Zabkar -- Please remove one 'i' from my address when replying by email. |
Strange CFL Failure Mode
Yep, soon they'll be considered as dangerous as incandescent lamps
that burn fingers, start fires, explode, send molten glass and tungsten shooting about and electrocute those who try to change the bulb. Please don't say that too loud, lest the electrician's union place a seal and/or lock on every fixture to assure only a licensed union electrician ever changes a lamp. Don't laugh. With all the microcontrollers embedded into everything, it's possible to add lockout codes so only authorized people may restart it, just like you car's "service required" light and reset code. It's bad enough my TV, monitor, radio and such all say "No user servicable parts inside". Pray, don't let that happen to my home too. My my, Terry. You do live an interesting and dangerous life ... During my many years of shuffling around on this little orb of ours, I don't think I have ever had a domestic incandescent light bulb start a fire, explode ... I had a night light bulb shatter, fresh from the package. I'd say that counts as an explosion. I swore off dollar store bulbs ever since. As to fires, I refuse to use lamps over 100 watts at home, thus avoiding the 300-500 watt halogen torchiere fires that were terribly common for a while. The closest I came to a lamp induced fire was a plastic figurine melting and smoking from being too close to a reflector halogen lamp. |
Strange CFL Failure Mode
Please don't say that too loud, lest the electrician's union
place a seal and/or lock on every fixture to assure only a licensed union electrician ever changes a lamp. Don't laugh. With all the microcontrollers embedded into everything, it's possible to add lockout codes so only authorized people may restart it, just like you car's "service required" light and reset code. It's bad enough my TV, monitor, radio and such all say "No user servicable parts inside". Pray, don't let that happen to my home too. Nobody else seems to have brought up that scenario with BPL. How about your refrigerator needing automatic updates and sending usage tracking back to the server, then crapping out because the most recent update no longer supports your model. |
Strange CFL Failure Mode
On Tue, 21 Jul 2009 19:40:49 +0100, Arfa Daily wrote:
"Nicholas Bodley" wrote in message ... On Thu, 16 Jul 2009 17:38:16 +0100, Arfa Daily wrote: I don't think I have ever had a domestic incandescent light bulb [...] This commentary reminded me of a quite-unpleasant experience in late boyhood. Apparently, an incandescent bulb in the cellar had a film of moisture on it (it had just been turned on). When I touched the glass, I got a nasty shock; damp concrete floor, etc. The socket must have been wired with its threaded shell to the hot side of the line. Not the bulb's fault, of course. Btw, hot glass is conductive, just about certain. Regards, -- Nicabod =+= Waltham, Mass. Well, if it is, and I rather suspect it's not, the amount of conductivity is very small. I work a lot with power valves (tubes) which run hot enough to take your fingerprints off in decimals of a second, and these often have as much as 800 volts on the anode pins. Some years back, I used to work with high power audio distribution amplifiers on a community radio network. The (foot high internally assembled with nuts and bolts) tubes on these 7 foot tall amplifier cabinets, often used to run so hot that the glass was actually glowing dull red. I have seen dents in the glass where the vacuum has started sucking on areas that have got *so* hot that they have softened. The HT supply on these beasts was about 2.5Kv as I recall, derived from mercury vapour rectifier tubes. Given these facts, if the glass had much conductivity when hot, you would pretty soon be into having leakage paths between the pins, and to the grounded retainer metalwork, that holds the devices into their sockets, wouldn't you ? Arfa Sorry for the delayed reply. If the glass is hot enough to soften, it's probably conductive to some extent. However, if surrounded by cooler glass, its resistivity would be too high to matter. Try this, but be aware that you're dealing with lethal voltages, high enough to jump a short gap (1 cm or so). You, specifically, most likely know how to protect yourself! If in doubt, others should not try this. Take a [neon] sign or oil burner ignition transformer (the latter is probably better) and arrange temporary electrodes (or use those in a discarded oil burner) to create a steady arc. That arc is like a flame -- it will melt and ignite materials. place a piece of well-insulated glass in the arc (safety glasses!), and let the arc heat the glass. When it starts to glow, or possible a bit sooner, it will become conductive; you'll see the arc divert so current passes through the glass. As to your power tubes/valves, you might have been lucky. Regards, -- Nicabod =+= Waltham, Mass. |
Strange CFL Failure Mode
On Wed, 22 Jul 2009 09:47:11 -0400, Victor Roberts wrote:
On Tue, 21 Jul 2009 19:40:49 +0100, "Arfa Daily" wrote: "Nicholas Bodley" wrote in message ... On Thu, 16 Jul 2009 17:38:16 +0100, Arfa Daily wrote: I don't think I have ever had a domestic incandescent light bulb [...] This commentary reminded me of a quite-unpleasant experience in late boyhood. Apparently, an incandescent bulb in the cellar had a film of moisture on it (it had just been turned on). When I touched the glass, I got a nasty shock; damp concrete floor, etc. The socket must have been wired with its threaded shell to the hot side of the line. Not the bulb's fault, of course. Btw, hot glass is conductive, just about certain. Regards, -- Nicabod =+= Waltham, Mass. Well, if it is, and I rather suspect it's not, the amount of conductivity is very small. I work a lot with power valves (tubes) which run hot enough to take your fingerprints off in decimals of a second, and these often have as much as 800 volts on the anode pins. Some years back, I used to work with high power audio distribution amplifiers on a community radio network. The (foot high internally assembled with nuts and bolts) tubes on these 7 foot tall amplifier cabinets, often used to run so hot that the glass was actually glowing dull red. I have seen dents in the glass where the vacuum has started sucking on areas that have got *so* hot that they have softened. The HT supply on these beasts was about 2.5Kv as I recall, derived from mercury vapour rectifier tubes. Given these facts, if the glass had much conductivity when hot, you would pretty soon be into having leakage paths between the pins, and to the grounded retainer metalwork, that holds the devices into their sockets, wouldn't you ? Arfa Ordinary incandescent lamps are made from soda lime glass, which has enough conductivity at 100C to maintain a low frequency (DC or 60Hz) discharge in T12 fluorescent lamps using electrodes on the outside of the bulb. The place where the wires are sealed in an incandescent lamp (the pinch seal) is made from lead glass, that has much lower conductivity than soda lime glass. Vacuum tubes are usually made from borosilicate glass (Pyrex(R)) that has even lower conductivity than lead glass, and much lower than soda lime glass. Aha! In the experiment I just posted a message about, I was using a glass rod, perhaps for stirring mixed drinks. It might well have been soda-lime glass. While typing, I was wondering about the conductivity of various kinds of glasses. Thank you, kindly, for the enlightenment. I s.t.r. reading, a long time ago, that Corning Glass used the resistivity of molten glass to keep it hot by passing a lot of current through it. I don't know how it mas heated to begin with, though. Best regards, -- Nicabod =+= Waltham, Mass. |
Strange CFL Failure Mode
On Thu, 23 Jul 2009 22:14:05 +0000, Don Klipstein wrote:
On the other hand, I have seen glass heated to the point of being soft conduct impressive amounts of current (several milliamps, possibly more) at a few kilovolts. I do not know what kind of glass was involved - either soda lime or a cheaper flint glass, probably soda lime. That surely describes the case in the experiment I described in a post a few minutes ago. Best regards, -- Nicabod =+= Waltham, Mass. |
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