Effect of light dimming circuits on line voltage sockets

Don't worry about it. The dimmers are undoubtedly designed to avoid disrupting radio communication for miles around. The chances of those chop wavefronts getting past the input power conditioning of electronic equipment and causing problems are very remote. Power lines are expected to be noisy. Anybody who tried to sell equipment that could not take the little bit of hash from your dimmers would see so much of it being returned to the retailer that they would soon go bankrupt. Your worry is the worst problem here.

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--Larry Brasfield
email: donotspam_larry_brasfield@hotmail.com
Above views may belong only to me.

I hope that you're right, Larry.

Lutron do issue an application note to advise on how to minimise the problem. But it would be a real pain to lay the lighting circuits in steel conduit.

By "cable-to-cable coupling", do you mean the coupling of noise in cables laid side-by-side? Or conducted from noisy circuits through the distribution panel to "clean" circuits? The first one is radiated noise, and the second one is conducted.

best bet is to buy lamp dimmers that include RFI filters

nip it in the bud.

Mark

Hi, Joerg.

so on. Most AM radios start to buzz and whine and I

going.

I was not addressing such phenomena.

That is the "it" the OP was worried about and asked about and which I have advised him to not worry about.

Yes, although most people do not notice dimmers' RF output messing up their reception, living in cities near the stations they receive. But the OP was not asking about that. He wanted to know whether he should bother separating some power cabling.

dimmers. Sure, filters and all take care of stuff but

It would be a sad audio amplifier that let that kind of garbage through from the line to its output audibly.

--
--Larry Brasfield
email: donotspam_larry_brasfield@hotmail.com
Above views may belong only to me.

Hello Larry,

Well, not quite. It gets radiated off the line and into antennas, radios and so on. Most AM radios start to buzz and whine and I have even seen sparkles on TV channel 3 when a dimmer to an outside lamp is going.

Cable to cable coupling isn't a big issue as far as I know. RF Radiation is. It's also a good idea to run Hifi equipment off a circuit that doesn't have dimmers. Sure, filters and all take care of stuff but only to a degree.

Regards, Joerg

There are different ways to dim ac lights. Consider how much you are willing to spend :)

1) Backedge chopping useing triacs. Will chop the end of the sinus wave. This is the standard one on sale in normal shops. 2) Frontedge chopping useing igbt?, Will chop the start of the sinus wave. 3) Pwm + filter useing ibgt/mosfet will smooth out the load over the whole sinus wave.

Hello Larry,

dimmers. Sure, filters and all take care of stuff but

Well, most of the "modern" stuff that I have seen is of pretty sad design quality. Nothing is grounded anymore and you easily get caught in a few ground loops. Turn on the dimmer lamp and a faint "bzzzzz" is heard.

Regards, Joerg

Hello,

Both. Cable-to-cable carries much of the higher frequency components that can mess up AM reception. Conducted happens because the line impedance at the panel isn't zero because the transformer is located away from the house. Even if it wasn't, the transformer doesn't provide low impedance at higher frequencies anyway.

Regards, Joerg

Actually, that is the wrong way round, triacs chop the start of the sine wave and igbts chop the end (or both the start and the end).

--
Tim Mitchell

The fourier transform should be the same for chopping the front or the rear.

Rene

--
Ing.Buero R.Tschaggelar - http://www.ibrtses.com
& commercial newsgroups - http://www.talkto.net

What I've read, in practice igbt approach is less rfi-noisy. Even thought what you say maybe is correct in theory.

Maybe over the long term, but what aobut the transients? I ddin't get that math course, but it just _feels_ different - like the difference between applying a voltage to an inductor versus removing current from it.

Then again, I just fix stuff. What the f*ck do I know? ;-)

Thanks, Rich