EMI: CFLs vs Incandescent Lights in Your Lab?

Question

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?

Answer 1

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.

Answer 2

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.

Answer 3

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.

Answer 4

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.

Answer 5

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.)

Answer 6

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.

Answer 7

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.

Answer 8

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.

Answer 9

I noticed that EMC test labs do not use CFLs in the chamber but stick to mains tungsten.

Answer 10

I am a recording engineer and cfl's create audible noise in my signal chain, as do dimmers on incandescents. Mine is just a small project studio so I have been able to go with ceiling mounted LEDs and Mighty Brite LED music stand lights. I only turn them on when I am hitting the record button because they are battery powered