Radio static goes with lights ON, why?
AM radio recption in my house has always been lousy, static-y. However, sometimes i want to listen to it instead of FM. Today I was listening to AM while cleaning off the massive light switch panel (Eight switches at the back door; don’t think that didn’t take a while to figure out where they all went.) Accidentally switched ON the lights to the side yard. Eureka! the static quit. WHY?? Seven years I’ve lived here with the static. Gonna move next year. Find out turning on lights drives away the static. I have taken back radios because the static was so bad. All I needed to do was leave the lights on. Doesn’t happen with any of the other lights on this wall. The radio may be on the same line as the outside lights, haven’t checked that out yet. Lights are on, radio is on, nobody home :^)
These switches are ridiculous. 2 blocks of four light switches, one block above the other. Not arranged logically. Four switches for outside lights on two different gangs. LIght switch for basement (which is to the left) is at extreme right. Kitchen is to the right, switch to the left. I have labels under them so I can remember what is what.
Replies
IMHO, assuming you don't have an electronic ballast or dimmer on the circuit, you have a loose connection in the portion of the circuit controlled by the switches.
I sometimes use a cheap AM radio, the type that run on a single 9v battery, fit in a pocket and have a telescoping antenna, to find arcing in large machinery rooms. I tune in a quiet spot on the dial and walk around. When I get the strongest noise I start manipulating the antenna direction and length to localize the source further.
You may be able to find the fault in much the same way. Finding the problem early may save larger repairs or even a get acquainted visit by your local FD.
The theory behind this is that an arc throws of a high amplitude square wave that effect the AM, Amplitude Modulation, spectrum. Some of the first radio transmitters using Morse code, dots and dashes, used spark gaps to create the wave form that create the signal.
4Lorn1 has probably forgotten more than I remember, but I disagree with his diagnosis. The static is caused by an electric arc, but the only way to get an arc is with current flow -- a complete circuit. I think you have a bad switch which is leaking current... just enough to cause static but not enough to light the bulb.
Your right that it could be a switch. Worn contacts can cause very small, they need not be great bolts of current to cause interference on AM, arcs that would cause the problem. A quick and easy, but not conclusive, check would be to flip switches until you get the noise and then slightly wiggle the switch lever while listening for changes in the noise. Sloppy of me not to include the switches themselves. My thanks to LEUCAS for the compliment and helping refine my answer.
Edit for spelling.
Edited 11/14/2002 7:26:17 PM ET by 4LORN1
So, switching the lights on, stops the arcing, right ?
(Forgive me if I sound dumb here. I am assuming that because it is an arc causing the static, then switching the lights on must somehow eliminate the arc, and therefore the static.)
Wouldn't it be most likely then, that it would be in the switch ? Flipping the switch creates positive contact on the points. Flipping it back off may be leaving the points just close enough to allow the tiny bit of arcing.
Where else could the arcing be occurring... that would not STILL be arcing if the switch were flipped ?
Seems cheap enough to just replace the switch with a good quality switch, and find out...
Don't bogart the Ghost
Quittin' Time
I had a problem with my reception the other night. I turned off the light that was closest and the reception got a lot better. The overhead light had one of the new low wattage compact fluorescent bulbs. Also I have a problem whenever the halogen spot light comes on (via the motion detector) the signal goes bad. I'm surprised because the radio is on a different circuit and some 20' away.
Now, I'd like some advise (best radio or antenna) on the best way to get the radio signals for both AM and FM and keep out the noise. I tend to listen to talk radio about 90% of the time and most of those stations are AM. I live in southern RI and can sometimes get stations (on the car) from Maryland, and Kentucky while not being able to get a station in Providence.
Thanks for any help, turtleboy
Don't forget that the static is present when the switch is OFF.
With a common AC switch the only way that you would have any arcing when it is open would be if there was LOTS of contamination with a conductive substances. Or the switch is broken internally. If it is broken then it would be clear by it's feel and/or it would have totaly failed by now.
This is a lot more "hidden" problem and will take some detective work.
One possiblity (and my gut says the most likely) is that the noise has nothing to do with that light or switch and possible not even that circuit.
Rather the noise is commoning from something else completely unrelated. What the light does is put a load on the circuit and that dampens the noise. Not unlike a furance fan causing the sheet metal duct to viberate. Put your hand on the duct will reduce or stop the noise, but the basic source is the fan.
In additon to your earlier suggestion of going around with the radio and sniffing different equipment start at the pannel and turn circuit off one by one until the noise stops.
But there are stranger esoteric reasons that turning the light switch on stops the noise.
One there is a loose connection with in that box and when the switch is turned you move things just enough to put pressure on connections.
Another possibily is that some place, and it could be any placce, on this circuit you have a loose connection. When the light is one enough current flow that the connectio heats up and makes a solid connection.
BTW, my experience is that motion sensor lights are know for making noise. They use a triac to switch the light (same basic part as a light dimmer), but they make absolutely no attemp at noise supression.
FWIW. We have a light sensor nite light that my DW installed in our bathroom. We too listen to AM. When the lights are on the night light is off and the AM is clear. When the lights go off the night light causes interference.
It only took us 6 months to figure this out...
I have a touch lamp that causes bad static when it's off. Noise goes away when its on bright. But that probably isn't the answer to your problem. I'd check the switch for loose connections. Current can flow with the switch off under certain conditions, especially if there is carbon from arcing, and some moisture etc present.
In my house the dimmer switch in the living room causes a static problem on my alarm clock radio upstairs in the bedrrom. ...that's not a mistake, it's rustic
It's hard to imagine a failure mode for a mechanical snap switch which would produce this result and still let you turn the light on and off. I'd be inclined to dig out the oscilloscope and look at the switch leg with respect to ground. If this is romex and the light is flourescent, maybe the impedance of the switch leg to ground when it's off is high enough that it can bring in RF from elsewhere. But all this is speculation. It may be interesting, but not particularly useful.
Early one morning, turn off all your breakers and the main. Replace any breakers that smell funny, or feel funny when you turn them on and off. Go through the panel making sure that all the screws are tight, especially neutrals and grounds. Make sure you have a good ground rod and good bonding. Then go thru as many boxes as you can around the house making sure all is clean and tight. Replace any marginal or worn switches, receptacles, and light sockets. While you're at it, re-arrange those switches so the locations make sense. Put a different bulb in that wierd staticy light. Put it all back together before sundown so you can turn everything on again. Continue the next day if you can't get to all the boxes in the house in one day.
This is a lot of dumb, boring work. But it's often easier to fix a really strange problem this way than by trying to find only the thing that is actually wrong. The cause may be something so subtle that you'll fix it this way without being able to tell at the time that you've nailed it. And sometimes it's a matter of two or more things wrong that together cause the symptom. Electricity has a wonderful talent for acting at a distance, and the cause of a problem can sometimes be dozens of feet away from the place where you detect it.
-- J.S.
It's the light switch that is failing. When I turn it on & off, I can hear a little snap crackle and pop inside it. Now I either get energetic and repair it myself, or do the helpless wifey act, and get DH to do it for me. Funny how I could do all these things when i was single :^)