We have tried to take the issue of LED traffic lights to the FCC.
Based on the reported signal levels, it is very likely that they meet the FCC
emissions limits for conducted emissions below 30 MHz and radiated emissions
above 30 MHz. This would leave the issue as one of harmful interference.
In the LED lights I have looked at, it is almost certain that the noises, at
least on HF, are being conducted differentially onto the 240 volt wiring
powering the bulbs. This decays very rapidly with distance in the near-field
region, so noise that is pretty strong right at the bulb is not very strong at
all a couple of hundred feet away. The FCC has stated pretty clearly that under
those circumstances, it does not consider the short-term interference to a
mobile station to be harmful interference. In my own experience, I believe I
could go to a neighborhood and find a place to operate, just not within 100
feet of the bulbs. Is that harmful interference, or not? So far, I'd have a
hard time imagining convincing the FCC that it is.
Now, if there were a fixed station right at the light, and that does happen,
there could be harmful interference. So far, ARRL has not had reports of
interference from LED traffic lights to fixed stations.
I will continue to concentrate on some of the other problems, as Dave says,
picking our fights wisely. Grow lights 40 dB over the limits and an FCC that
won't enforce even its own Citation and Orders are a first priority right now.
Pulse-wide control motors are also a growing problem, as are certain lighting
devices being sold into residential markets, even though they don't meet the
residential limits.
Ed Hare, W1RFI
ARRL Laboratory Manager
225 Main St.
Newington, CT 06111
Tel: (860) 594-0318
Fax: (860) 594-0259
Email: W1RFI@arrl.org
Member: IEEE Connecticut Section
Member: IEEE EMC Society, Board of Directors
Member: IEEE EMC Society Standards Development and Education Committee
Primary representative: ANSI ASC C63 EMC Committee, Vice Chair Subcommittee 5
(Immunity)
Member: QRP Amateur Radio Club International, Board of Directors
-----Original Message-----
From: RFI [mailto:rfi-bounces@contesting.com] On Behalf Of David Cole
Sent: Monday, July 27, 2015 1:38 PM
To: rfi@contesting.com
Subject: Re: [RFI] LED lighting
Hi Cortland,
I have noticed that, but, like the ARRL we are picking our fights...
Going for the items that affect the most hams in the area first.
--
Thanks and 73's,
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On Mon, 2015-07-27 at 13:11 -0400, CR wrote:
> On 7/27/2015 12:55 PM, David Cole wrote:
> > City here is going to be switching to LED streetlights soon, and
> > ended up in contact with the City Engineer...
> >
> > The long and short of it is that the city had not even thought about
> > Part 15/18 compliance, but when they looked, the lights were
> > compliant
>
> LED stop lights, however, have been known interferers for some time,
> probably due to noisy SMPS and long lines to the timers and controllers.
>
>
> Cortland Richmond
> KA5S
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> RFI@contesting.com
> http://lists.contesting.com/mailman/listinfo/rfi
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