[RFI] RFI from HIGH voltage power lines

RFI Services' Michael Martin mike at rfiservices.com
Fri Jun 1 08:01:09 PDT 2012

Hey Guys,
The rule is basically, the more insulators the better prepared they are for
the voltage. The number of insulators can be an indication of the
approximate voltage but that is not reliable. 230kV is going to have a
string of insulators about 8 feet long. That would mean they can apply that
limit. Many times, especially newer construction, they will build in over
kill to allow for future growth. The best way to figure the voltage is to
follow them back to the station and look at the equipment just inside the
fence. Usually the equipment will be marked in some way to help you
determine the voltage. Google Earth is a good tool to use to figure out the
direction of the closest station.
On the average I'd guess, from your description, the range of 138kV. That's
a guess.
As far as noise (RFI) issues, the wood poles are key. Wood shrinks and the
loose hardware due to that shrinkage is the main issue of concern. The
higher voltage adds to the level and distance it will travel because of the
lesser amount of Line equipment to help filter or dissipate the noise as it
is radiated and conducted down the line.
RFI caused by power lines isn't usually held to a higher level of importance
because of the line voltage, so don't consider that a plus. 

It is my experience that a utility that is concerned about being a good
neighbor, or however you want to refer, is going to fix the issue regardless
of the voltage. As long as the RFI locating process isn't shot gunned, the
cost for repairs on any voltage system is minimum. The costs are usually
elevated because of the process they use to locate them and eliminate the

I know of situations where a utility has spent hundreds of thousands on
repairs and not touch the source and then some that spare no expense to
learn the correct way to do it to eliminate excessive cost of ignorance.

As someone else suggested, go to the area where you are concerned with and
setup camp or park and perform the hobby. If you get noise call the utility
and see first-hand what to expect from the provider if the condition exists.

Michael C. Martin
RFI Services
6469 Old Solomons Island Rd
Tracys Landing, MD 20779

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