Why are the electrical lines outside my house suddenly making a loud,
chirping noise?

---

Request for Question Clarification by techtor-ga on 28 Sep 2003 04:59 PDT

I just want to ask about a few things that may help answer this
question, since I am not there myself to see what's really happening.
Are you sure it is from the power lines, and that there can be no
other source of the sound? What else can you observe about the power
lines? Is there a part where the noise is loudest, such as near the
electric post or in the middle of hanging lines? Also, it is windy in
your area?

---

Request for Question Clarification by techtor-ga on 28 Sep 2003 05:10 PDT

By the way, I'm working from the assumption that the power lines in
your area are hung from tall posts as opposed to underground.

---

Clarification of Question by tory-ga on 28 Sep 2003 10:10 PDT

Yes, the power lines are above the ground.  We are pretty sure it is
the power lines but we also have cable lines that run next to them. 
We have had the electicity company come out twice to listen -- they
hear the noise but don't know what is causing it.  They thought it was
maybe because the lines were wet, but this noise has been going on for
over 3 weeks, when it has been dry.  They cut some branches away, but
it didn't help.  (we live outside of Boston, not very windy.)  We
can't pinpoint exactly where the noise is coming from -- it seems to
be coming from several wires.  The noise is constant though and we
figure there has to be a solution since it wasn't there before. 
thanks

---

Request for Question Clarification by hedgie-ga on 04 Oct 2003 00:51 PDT

If the noise is still there, and really bothersome 
it may be necessary to do some measurements. The
given description, based on unaided observation is
not enough. It should be possible ask environmental
agency to do that, to measure the spectrum of the
acoustical noise and of the emg field and see if
there is a corelation. There are also devices which
can pinpoint location of the sound. It may be something
as simple as cracked insulator which is sparking,
but you need more data to determine that.

The clue may be in the 'cable lines' that run next to the electrical
lines.

If these are not properly shielded - or if the shielding has broken
down - then electromagnetic radiation could be escaping ... and
induced into the power line.

Does unplugging your telephone, tv or computer (or whatever runs down
the cable) have any effect on the noises?

Thats a good point probonopublico-ga, however electromagnetic
radiation would only create electrical noise.

If you hear a noise which is not constant then the problem is most
likely gap sparking.  Do you have electrical interferance on your TV
attenae?  Then thats the problem.

I believe that the problem is from something called Corona noise. This
happens when the voltage at the surface of the wire overcomes the
dialetric strength of the air.  Basically the air around your wires
have become a conducter.  You should hear a constant broadband noise
with a strong tone at 100 Hz. (audible frequency)  Ozone is also
developed from Corona noise! This problem may start for a number of
reasons.

It sounds like Aeolian noise generation is not the problem. (Noise
from wind going over the wire) But to be sure, do you know the
diameter of the electrical wire, and the temperature outside?

It would be helpful if you described the sound in more detail. Is it
really just a sudden "chirp"? How frequently does it occur? Does it
follow a pattern such as one or two chirps per second, etc., or is it
mostly random? Is the level of activity fairly constant 24 hours per
day, or does it vary based on day or night or some particular time of
day? Is it affected by rainfall, bright sunlight, hot or cold
temperatures, wind, etc.?

If the cause of the sound is biological you ought to see a clear
pattern based on some of the above-mentioned parameters. If the cause
is mechanical (i.e. wires rubbing, etc.) there still ought to be some
correlation. Even electrical causes will probably follow some sort of
pattern, since most residential powerlines experience their greatest
load during early evenings, and leakage etc. usually occurs more often
during or just after damp weather.

I wouldn't entirely discount the possiblity that the source of the
sound might be elsewhere, since certain sounds (especially
higher-frequency sounds) can bounce off many objects and can be quite
tricky to locate.

Here's a simple test you can perform that might help you to determine
whether or not the sound has an underlying electrical cause (such as
leakage, arcing etc.):  Get a small portable AM radio (the cheaper the
better) and tune it near the low end of the AM dial, but BETWEEN
stations. Take it outside under the wires, turn the volume up high and
listen for any static or similar noises coming over the speaker that
occur at the same time as the chirping sound.

You can also perform the same test with a longwave radio if you have
access to one. Some multi-function portables include a longwave band
(just below the AM band). In this case I would try tuning through the
entire longwave band while listening for the source of the chirps.

If you don't mind spending $12 or so, Radio Shack has a device called
a "telephone listener" which can be used in a similar fashion. It is
actually a longwave receiver with a little suction-cup antenna. Just
stand out there under the wires, turn the volume up high and
twist/rotate the antenna around until you find the position that
produces the strongest signal. You will mostly be hearing the 60-cycle
hum coming from the wires, but hopefully you will also be able to hear
the mystery chirps, if they are electrical in origin.

First of all, it is an effect on the air that you hear.  Secondly, if
the frequency of the "chirping" is discernable, it would have to be a
beat.  the frequency of the electricity is 50 hertz or more, this
would not be discernible.  The fact that we are undoubtedly talking
about a beat is not an answer, but it might be a clue.  Hope it helps
in some way.