THD In Light Bulbs


I have replaced a 40w incandescent light bulb with a 12w LED light bulb. The new LED is way brighter. In fact, the box says that it's a 75w equivalent. The box also shows something interesting:

Power Factor >.90  
THD: <35%

I've read that LEDs are essentially diodes. How does this affect noise in the mains? Do LEDs inject more, less, or the same amount of THD into the mains as incandescent/fluorescent lights? 
c_avila1
My biggest concern is that LEDs may inject more noise into the AC line than incandescent light bulbs. If that's the case then I'll continue to use incandescent bulbs. Also, I've recently installed Akiko Audio and Perfect Path Technology products in my system that helped clean up noise in my AC. It's important not to counteract their effects. 
Summary:

  • If you have no dimmer on the line, then the incandescent bulb will inject less noise.
  • If you have a dimmer on the line, but the dimmer is on full, the LED will likely inject more noise. It will depend on the dimmer and LED bulb.
  • If you have a dimmer on the line, but the dimmer is not on full, the LED bulb will inject more high frequency noise, but the incandescent bulb will inject more low frequency noise (as it will be drawing 5-6x the power). I can't comment on how your specific equipment will behave.

Unfortunately there are no absolutes, but this is about as good a guideline as can be given.
Thank you @audiozenology. That summary was all I needed.

 My television and computer monitor are full of LEDs...oh well.
If it wasn't LEDs it would be compact fluorescents or vacuum tubes. They would use more power and there would be even more noise. LEDs are not noisy, just the power supplies used to drive them.
There is more to electronic noise than the THD.   Power factor also comes into play.   The OP's bulbs  seem to be pretty good with a Power Factor >.90.   Many of the cheap ones are not Enerystar rated have a power factor ~50%.   That means that half of the power going in is wasted and the unused "power" is dumped into the neutral leg.  And while the THD: <35% does not sound that good hopefully it is much <35%.  A good bulb can be ~ 10%.   But generally if a good manufacturer cares about their design power factor and THD are both optimized.    


So the take home message is you should look up the specs before you start swapping out your incandescents and don't buy the cheapest dollar store brand bulbs.