[RFI] Low voltage lighting solid state "transformers"
jim at audiosystemsgroup.com
Sun Dec 17 16:04:00 EST 2006
On Sun, 17 Dec 2006 11:07:56 -0700, Steven Farmer wrote:
>Since my rfi seems to be mostly a common mode problem, some
>sort of emi filtering at their breaker panel might also work.
I doubt it. The AC wiring between the noise source and the filter will
act as an antenna, and in a typical building, is likely to be long
enough to be a pretty effective radiator on the HF bands. Now, IF the
AC wiring happens to be in grounded metallic conduit that is properly
bonded at both ends (or at least bonded to the noise source), you are
in FAR better shape. That's more likely to be the case in an industrial
building, less likely in residential. And even in industrial buildings,
I'm seeing a lot more PVC pipe rather than EMT, because it's a lot
cheaper to install. That, of course, provides no shielding at all.
The depressing thing about all of this is that everyone involved is
playing cheap, and we pay the price. Cheap power supplies, cheap
electrical, no filters, cheap Congress (no funding for FCC to enforce
its rules), and in the case of these devices, rules (Part 18) that seem
to allow this garbage equipment to be sold.
Perhaps someone working in the EMC world might venture an opinion as to
whether there might be grounds for approaching FCC on this issue. The
lighting people will tell you that their stuff is exempt under Part 18.
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