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View Full Version : Listen to channels pulse, at the breaker box.



Michael
10-29-2007, 12:58 PM
Last night while trying to trace another power problem I noticed I could tell where in my show I was be listening the the hum or buzzing in my breaker box. This was really loud during the full on/off rapid flashing sections. Could hear it about 6 feet away. I am using the best quality Square D breakers I could get. The display is using less than 10 amps total and only one breaker.

Should I be worried about this, or is it normal?

- Michael

BillAd
10-29-2007, 01:39 PM
Michael,

What happens if you select an outlet feed by a different breaker?

BIll

Michael
10-29-2007, 02:02 PM
That is a good idea for a test. I will have to run a long extension cord to get to that area, but I will try it tonight.

- Michael

DynamoBen
10-29-2007, 07:46 PM
If you are dimming your lights this humming is expected and normal. SCR style dimming creates harmonics on the neutral which will lead back the powers source, your breaker box. There really isn't any way to economically correct this.

In larger dimmer installation a K-rated transformer is installed prior to the dimmers to "dampen" this harmonic.

Jeff Millard
10-29-2007, 08:47 PM
I agree wholeheartedly with Ben on this one. I installed the 200amp service in my home myself. Then ran ten 20amp circuits directly to a case that has 10 GFCI outlets wired feed-through to 13 LOR controllers. Everything has been checked and rechecked for tightness and construction.

When the lights are flashing and dimming and shimmering and making faces light up...

The breaker box is singing out for joy! I am hard of hearing and didn't notice it until it was pointed out to me. At first I was worried about it. Trying to decide if it was something I forgot... When I talked to co-workers about it, they just told me to be quiet and listen to the substation we were in... it sounds just like the breaker box in my house...

Jeff

NogginBoink
10-29-2007, 09:50 PM
Has anyone considered adding snubbers to their SSR's to help combat this?

DynamoBen
10-29-2007, 10:58 PM
This isn't something you can correct very easily. Traditionally you would oversize your neutral going from your dimmers to their power source (double or triple). However with such a small system you may not hear/see any change. The other option is to change dimming methods. In the end as long as you are chopping up the sine wave you will get this hum.

If memory serves, in some areas of the world the electrical company actually measures the harmonics induced to the grid and charges for it. That’s why one of the major selling points of the new sine wave dimmer is that they don’t create harmonic distortion.

BTW with SCR dimming you always want to run your neutral next to your hot. If you split the two not only will the hum get worse, but you will end up with very hot wires that can catch fire. This isn't generally and issue for us because we use extension cords, but it is something to remember. The rule is "never separate your neutral and hot, over long distances."

Read:
http://www.epanorama.net/documents/lights/lightdimmer.html#harmonics

Michael
10-29-2007, 11:36 PM
Thank you very much for these detailed answers. That makes me feel much better now. And every now and then I might setup a chair next to the breaker box and listen to the show in a new way.

- Michael

xmus
10-29-2007, 11:41 PM
This isn't something you can correct very easily. Traditionally you would oversize your neutral going from your dimmers to their power source (double or triple). However with such a small system you may not hear/see any change. The other option is to change dimming methods. In the end as long as you are chopping up the sine wave you will get this hum.

If memory serves, in some areas of the world the electrical company actually measures the harmonics induced to the grid and charges for it. That’s why one of the major selling points of the new sine wave dimmer is that they don’t create harmonic distortion.

BTW with SCR dimming you always want to run your neutral next to your hot. If you split the two not only will the hum get worse, but you will end up with very hot wires that can catch fire. This isn't generally and issue for us because we use extension cords, but it is something to remember. The rule is "never separate your neutral and hot, over long distances."

Read:
http://www.epanorama.net/documents/lights/lightdimmer.html#harmonics


So is this a bad idea?
http://www.doityourselfchristmas.com/forum/viewtopic.php?t=920&highlight=smoke

BillAd
10-30-2007, 08:57 AM
Make me wonder.... The sound must be generated by some portion of the electrical breaker box components vibrating. If the vibration is internal to the breaker then how long will it take to cause enough metal fatigue to cause failure. Just a thought, not a worry.

Bill

DynamoBen
10-30-2007, 11:08 AM
So is this a bad idea?
http://www.doityourselfchristmas.com/forum/viewtopic.php?t=920&highlight=smoke

Not a bad idea, you just might need an additional load to keep the SCR in its on state. Again the light bulb test is a good one. If you need up needing an additional load a 10 ohm 10 watt resistor may do the trick.

I am a little surprised that the remote is using 120AC to control smoke output. The one I have uses 12V DC to fire a relay in the fogger.

kostyun
11-14-2007, 01:05 PM
I had read about this last week - and I took a listen at my breakers also - and they do sing along to the music also!! Quite interesting!