I think that another factor in shortening the life of incandescent lights is the fact that they are usually mounted in a heavy glass protective fixture. These glass globes offer a bit more safety from physical damage, and also look nicer than a bare light bulb in a socket. But the light bulb runs a lot hotter when you use the globe. I think this shortens the bulb life too.
In my chambers, I have gone to bare bulbs in sockets. Of course, since my chambers are 9 feet tall, the bulbs are fairly safe even when people are moving large objects around (I have never had anyone accidentally hit a bare light bulb). I now use ordinary 100 W bulbs in open fixtures, and, over the past two years, my bulb life has improved to a point where I don't even think about it any more. BTW, my facilities guys wanted me to use some exotic industrial grade bulbs. IIRC, they were rated at 135 V for 100 W (so I suppose they were NOT 100 W bulbs at 120 V <g>). These bulbs were slightly longer and larger than an ordinary bulb, and had an anti-breakage Teflon film on the bulb surface. This gave then a "satin" appearance. However, those bulbs burned out just about as fast as ordinary bulbs (I was using them within globes at the time), and I since they cost several times more, I stopped using them. Regards, Ed Ed Price ed.pr...@cubic.com Electromagnetic Compatibility Lab Cubic Defense Systems San Diego, CA USA 858-505-2780 (Voice) 858-505-1583 (Fax) Military & Avionics EMC Is Our Specialty Shake-Bake-Shock - Metrology - Reliability Analysis >-----Original Message----- >From: richwo...@tycoint.com [mailto:richwo...@tycoint.com] >Sent: Thursday, October 31, 2002 12:00 PM >To: emc-p...@ieee.org >Subject: RE: Shield Room Lighting > > > >We have the same frequent burn out problem and we also have >attributed it to >the filters. We just keep replacing them. Has anyone tried the >rugged bulbs >marketed for use with garage door openers or ceiling fans or >have tried the >extended life bulbs? Do they last longer in chamber use to >justify the cost? > >Richard Woods >Sensormatic Electronics >Tyco International > > >-----Original Message----- >From: POWELL, DOUG [mailto:doug.pow...@aei.com] >Sent: Thursday, October 31, 2002 12:49 PM >To: EMC-PSTC (E-mail) >Subject: Shield Room Lighting > > > >Greetings all, > >I wanted to share an experience and I hope benefits someone else. > >My past experience with shield room lighting is that incandescent bulbs >frequently burn out, about once every 2-3 months. I tried >ruggedized lamps >of various sorts, still with the same results. Obviously, I >wanted to avoid >florescent lighting because of the huge fields they radiate. >After some >investigation and discussions with co-workers, it became >apparent that the >problem is the line filter for service power in the room and >the tungsten >filament in the bulb. These line filters are typically have a >really large >line to neutral capacitance which significantly lowers the >source impedance >of the line. Coupled with this, tungsten experiences a >fairly high in-rush >current owing to it's very dynamic negative temperature coefficient. I >toyed with idea of using inrush limiters but I thought there >had to be a >reliable low-tech solution. And at all costs, whatever >solution I used, I >wanted to avoid injecting unwanted RF noise into the room. > >I discovered traffic light signal bulbs. Available from a few sources, >these bulbs have at least 5 filament supports, heat dissipaters and >reflectors and are designed for continuous on/off operation in >all sorts of >weather conditions. They even keep working when the hanging >fixtures bang >into each other in wind storms. I also learned that these >bulbs have about >a 1 to 2 year life expectancy in these conditions, so I tried >it out in my >room. So far, I've logged a full year of use on 4 x 150W >bulbs with no burn >out. And no, I don't just leave them turned on. > >If you want to try this, do it soon because it appears that >these bulbs may >become a thing of the past and prices may be driven up. Over >the last few >years, many cities and counties are replacing their >incandescent bulbs with >the new LED bulbs and with great success. As soon as a white LED light >becomes available I may try it out, although I guess I could >use red LED >lamps since I used to be in the navy. > > > >Best regards, > >-doug > >Douglas E. Powell >Compliance Engineer >Advanced Energy Industries, Inc. >Fort Collins, CO 80535 USA > > ------------------------------------------- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on "browse" and then "emc-pstc mailing list"
