Radio Frequency Interference T5 vs. T8

[MN4x4]

I have been reading about RFI problems with various fluorescent lights. I assume it's the ballast, and was wondering if T5's are worse than T8's, or vice-versa. Or are they pretty much the same?

If anyone knows themselves or has source they can point me to I would really appreciate it. I am ready to purchase lights and would like to NOT make a mistake.

 

[Gary S]

You are correct. It is the ballast that generates the rf interference. Electronic ballasts are designed to operate at rf frequencies to eliminate flicker in the lamp. Any difference between a particular T5 and a T8 would most likely be due to different shielding in the ballast and fixture.
The lower frequency old ballast transformers were not operating at high frequencies, so they seldom caused interference in the rf bands, but then you see the flicker in the lamps.

 

[kbs2244]

Gary S
Are you saying that you do not get the "strob light" effect with an electronic ballast?

I have always been afraid of fluorescent only installs around power tools because that effect can make saw blades and such seem to be standing still when they are in fact spinning.

I have always used regular bulbs in addition to the fluorescent bulbs in wood shops and such.

 

[Gary S]

There should be very little if any strobe effect with high frequency solid state ballasts. The old transformer ballasts operated at line frequency of 60 cycles per second. The human eye can see that as flicker. The electronic ballasts operate at 20,000 cycles or higher. Your eyes can't see that as flicker. If your saw blade was running at that speed, and IF all your high frequency lights were syncrhonzed (which isn't possible), you might see something. With the old lights all syncronized at 50-60hz, it was easy to see flicker.


From a site that knows more than I know.
"Electronic ballasts usually supply power to the lamp at a frequency of 20,000 Hz or higher, rather than the mains frequency of 50 - 60 Hz; this substantially eliminates the stroboscopic effect of flicker, a product of the line frequency associated with fluorescent lighting (see photosensitive epilepsy). The high output frequency of an electronic ballast refreshes the phosphors in a fluorescent lamp so rapidly that there is no perceptible flicker. The flicker index is used for measuring perceptible light modulation ranges from 0-1, with 0 indicating lower possibility of flickering and 1 indicating the highest. Lamps operated on magnetic ballasts have a flicker index between 0.04-0.07 while digital ballasts have a flicker index of below 0.01."

 

[Tom McDermott]

There shouldn't be much difference between T5 and T8.

Make sure the that you purchase ballasts (or fixtures incorporating ballasts) that are marked for residential use, not those marked for industrial or commercial use.

Specs for residential use require significantly lower levels of RF interference.

-- Tom

 

[kbs2244]

Thanks for the strobe info.
I can use that.

And, yes, getting the residental units is very much worth it.
Even though it seems backwards.

 

[ddawg16]

When someone complains about the strobe effect with CFL's....that is a good indication that it's all in their head....they just 'think' the light is strobing...

The old T12 lights with the magnetic ballast actually operated at 120 Hz. A diode bridge rectified the AC for the 120 Hz. The human eye can't really see any light freq above 60 hz...so.....in a properly operating T12 fixture....the eye can't see the strobe effect. You only get it when bulbs or ballasts start to fail.

 

[Kevin C]

The only advantage the industrial ballast have is they have power factor correction and are capable to run on a much wider voltage range.

Power factor correction matters when you have a lot of lights. Without it the peak current draw is out of phase with the peak voltage. That reduces how much actual power can be delivered on a circuit and may cause a buzzing from your circuit breaker.

I have 12, 4' T8's on a 20 amp circuit and you can hear a slight hum from the breaker.

There are ballasts that have PFC and that are rated for home usage... Its just hard to find them.

 

[Tom McDermott]

In industrial areas there are lots of motors, machines, and things that make a tremendous amount of electrical noise. Thus low RFI emissions could be somewhat masked by all the other electrically noisy stuff around.

In residential areas it is electrically a lot quieter, people want to listen to radio and TV, and may be more distant from broadcast transmitters, etc. So more strict RFI noise emission limits for all sorts of devices make sense.

-- Tom

 

[bookman51]

In another thread I post that I solved the problem of RFI from industrial balasts in my T-5 lights with: 1) a remote antenna; 2) shielded coaxial cable from the antenna to the stereo receiver; 3) purchase of a used stereo receiver with coaxial input for the antenna; and 4) putting speaker wires in metal conduit to shield them. Don't know if all of these factors would solve the problem in another situation or not but worked for me.