On Mar 7, 10:52?pm, wrote:
Hi. I know nothing about amateur radio nor electronics so I'm here looking for
an answer to a question which bothers me. There are a number of places near
where I live that, if you drive by them with the AM radio in the car on, there's
an extreme amount of noise. It usually last while driving parallel to overhead
wires (not high power lines, must the ones on poles), then goes away. It's
always the same places and doesn't come or go. I'm guessing bad shielding of the
wires. My concern is, if it does this to the radio, is it harmful to people who
are near it? Thanks.

Like Steve remarked, the noise you hear isn't harmful.

Overhead electric power distribution lines aren't shielded.
With time and exposure their insulators, even the wire
(if covered with insulation) will accumulate semi-conducting
dirt and grime. That can cause minor to major arc-overs
which are short-impluse energy spikes. Since those are
of very short duration their bandwidth is wide and can
spread the impulse energy up into the VHF range of
FM broadcast band.

In newer construction the electric power distribution
lines are underground, generally through metal conduit,
and don't get a change to radiate wideband RF energy
nor are there as many arc-overs.

If the irritation from picked-up noise is a bother, it can
be reported to the local power utility. It's touch and go
whether or not they do anything about it, though. It is
only an irritant to radio listeners and not harmful to any
human...but it is covered by FCC regulations as
"incidental, unintentional RF radiation" and has limits.

73, AF6AY

On Mar 8, 3:34 pm, "
wrote:

but it is covered by FCC regulations as "incidental, unintentional
RF radiation" and has limits.

Congratulations on your license, Len.

It is probably best not to mx "unintentional" into that explanation
because under Part 15, "unintentional emitters" are treated
differently than "incidental emitters."

In the US, under Part 15 of the FCC's rules, power lines are
classified as "incidental emitters" -- devices that do not
intentionally generate RF signals inside of them, but that may do so
as an incidental part of their operation. Examples of incidental
emitters are electric motors or the power-line noise sources being
discussed.

Unintentional emitters are devices that do intentionally generate RF
signals internally, but that do not intend to radiate them. Examples
are computers, calculators and most digital devices.

Under the rules, indidental emitters do not have any specific radiated
or conducted emissions limits. The manufacturer of an incidental
emitter has a responsibility to use good engineering practice
(whatever that may be construed to mean) and the operator of the
device must do so in a way that does not cause harmful interference to
licensed radio users.

73,
Ed Hare, W1RFI
ARRL Lab