# EMI: CFLs vs Incandescent Lights in Your Lab?

Being a green-oriented treehugger, I've put in all CFL lights in my house. Just as much light for about 1/4 or 1/3 the power. Nice, but flourescent lights put out a lot of EMI. Does this cause trouble for anyone? What are your experiences of CFL or other flourescents versus incandescent bulbs in the room or house where you do sensitive electronics work? Does anyone stick with ol' tungsten just to keep EMI down?

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Doesn't this site have the "community wiki" concept? This question ought to be one, but I see no button to make it so. –  DarenW Oct 17 '10 at 4:20
It does normally but I couldn't see the tick box when I looked just a moment ago, and I appear to have no option to make your post a CW post. –  Amos Oct 17 '10 at 12:45
I figured maybe it is a matter of having enough rep points? But you have plenty... –  DarenW Oct 19 '10 at 2:36
If anyone is lucky enough to see a CW button on this page, go for it! –  DarenW Oct 19 '10 at 2:47
@FakeName, it is not removed, but it requires a moderator so we can decide when it is a bad question someone is trying to sneak by. I have made it. You just have to flag for moderator attention and request it. –  Kortuk Nov 30 '10 at 23:45

CFLs are not very green at all, there's enough components inside them to make a ham radio transmitter!

They use so many different third party components - the cost in resources and transportation of CFLs and their constituent parts far outweigh the environmental impact of using a regular incandescent bulb.

It's a fallacy that CFLs are greener, and I've not seen any evidence to suggest they are.

However - What they are good at is reducing power consumption and running cost, so from the users point of view they're great for reducing the energy bill, just not so great at reducing the impact of electrical lighting on the planet and it's resources.

More efficient != More environmentally friendly

With regard to EMI - I work with audio, it's quite common to get interference on audio or signal lines that run close to a large lighting ballast or power transformer. My advice is to keep power and signal lines separate when possible, but they'd have to be pretty close in order to have an effect. The only time where I'd get anal about it is when fitting lighting in a sound recording studio, I've used so many badly wired studios over the years that I'd insist on having the lighting ballasts in a separate room.

REVISION:

I should be corrected - my reason for believing CFLs are bad looks like misinformation - a commonly held misconception - doh!

I retract my earlier comment that:

the cost in resources and transportation of CFLs and their constituent parts far outweigh the environmental impact of using a regular incandescent bulb.

I'd like to replace it with:

the environmental impact of using a CFL far outweighs the environmental impact of using a regular incandescent bulb.....probably :)

I do still have an issue with CFL mercury content, it's really bad for the environment, but... as things are currently - I admit CFLs are the lesser of two evils when you consider how the majority of electricity is generated

So I guess it's not so easy to say which is better, maybe we need more data to make an informed decision, I remain unconvinced with CFLs green credentials.

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Cite your sources? –  Thomas O Oct 17 '10 at 12:57
This video has an excellent discussion on why the mercury content in CFL's isn't actually worse for the environment: youtube.com/watch?v=cA2E14uKyZY –  Thomas O Oct 17 '10 at 20:07
theres lots of comical analysis when it comes to people trying to be "green". The Prius is a great example. Everyone forgets how nasty the chemicals required to make the batteries are and how much more energy the thing takes to produce than your average compact car. Not to mention disposing of said batteries. they only see 60mpg and think they are being green. Buying a 1995 4 cylinder with 30mpg and overhauling the engine would have a far lower overall environmental impact. –  Mark Oct 17 '10 at 21:11
Probably. I can't honestly see how the Prius is green given all its energy comes from gasoline (you can't recharge it can you?) Now a Tesla, that is green and awesome at the same time (second fastest vehicle in the world, 1st fastest is some Ferrari.) –  Thomas O Oct 17 '10 at 21:59
The video was great, it cleared up a few things, but I guess it also proves that green living is very individual, If you use a green energy source then incandescent may be an option, but for the majority- I agree CFLs are still the best option –  Jim Oct 17 '10 at 22:06

I have CFL bulbs in both of my lights and in fact around most of the home. No particular reason other than they were giving them away at 20p each and they do save energy.

My test equipment seems sufficiently isolated that this causes no problems whatsoever. But... in order for the manufacturer to sell these, they have to already meet EMI standards.

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The only time I have experienced the type of trouble you mention was in a room where we did measurements with radiated EMI up to some 100 MHz. Electronic ("green") ballasts were installed for the fluorescent lamps in there, and we could clearly see them (and not our DUT) on the spectrum analyzer. We went back to simple mains frequency chokes and things were a lot better again. I guess the same reasoning goes for compact fluorescent lamps.

Other than EMI measurements with test receivers or spectrum analyzers, I wouldn't expect trouble. Hacking radios with dimmed incandescent bulbs on in the same room usually is worse than interference from CFLs.

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I used to work for a group that had dimmers on their light circuits, which worked fine until they switched to dim-able CFLs. I am not sure what it is about them, but they caused tons and tons of noise in our audio system when ever they weren't fully on or fully off.

But, to answer you, the way I look at it is we should deal with any noise from the environment so that we know that the electronics we design can handle the noise.

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In other words - just include any noisy CFL or other household contraptions as part of your test equipment? –  DarenW Oct 19 '10 at 2:39

Have you considered using LEDs? It can take a bit of work to get the spectrum right, but they dont produce any EMI, and in my experience, they tend to be more energy efficient than CFLs.

### Edit:

The other main problem for LEDs is their higher cost. LEDs last even longer than CFLs, so it evens out in the long run, but it does put some prohibitive front-loading on LEDs. OTOH, people who worry about front-loading more than long-term efficiency probably wouldn't switch away from incandescents in the first place. (As far as I know, CFLs are still more expensive (initially) than incandescents.)

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I love LEDs but to have a realistic amount of illumination throughout the house is yet too \$. –  DarenW Nov 10 '10 at 16:20
BTW, a few years ago I did rewire a camping trailer to use LEDs in place of incandescent. Used a mix of red, orange, yellow, green and white for balance. Cut the amps pulled from the sun-fed batteries to something like 1/5th or 1/10th of what it was. –  DarenW Nov 10 '10 at 16:22
@DarenW(0), see edit. –  David X Nov 11 '10 at 1:19
LEDs are no better (generally worse) than CFLs as far as power use per lumen. They can be convenient if directed light is needed, but for general illumination they are a novelty. –  Nick T Nov 11 '10 at 16:56

I have seen signal of 3x CFL on input of 19-22 bit stereo DAC as a single very narrow peak more than 10Db above noise floor. Distance in air was about 5-10 feet. The signal was puzzling me, until I spotted CFLs and turned them off.

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We do alot of work with IR in rooms. CFL put off a larger amount of IR radiation, modulated, so it can make certain tests change.

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Agree, all high frequency ballasted fluorescents put out some modulated RF with components at IR frequencies (36-38kHz), but compact fluorescents are worse than linear tubes. –  Martin Mar 29 '11 at 8:12

I keep CFLs out of my 'shack and antenna areas, but use them elsewhere. They do seem to generate some ugly RF, but it's relatively low power so can be insulated with distance. :-)

Still using incandescents in the shack at the moment as I happen to have them laying around. Might as well use them. Once I run out, I plan on LED lighting. I don't like the limitations of the LED lighting, but I don't really see any viable options at this time.

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