Power supplies face no FCC Part 15 radiated RF tests below 30 MHz. There
IS a conducted emissions test.
QUOTE
Section 15.107 Conducted limits.
(a) Except for Class A digital devices, for equipment that is designed to
be connected to the public utility (AC) power line, the radio frequency
voltage that is conducted back onto the AC power line on any frequency or
frequencies within the band 150 kHz to 30 MHz shall not exceed the limits
in the following table, as measured using ...
END QUOTE
For Class B, 0.5 - 5 MHz the table shows 56 dBuV measured quasi-peak or 46
dBuV average. 46 dBuV is 200 microvolts and 56 dBuV is 3.162 times that,
631 microvolts. Class A -- a lot of Class A is (unlawfully) marketed into
the residential environment -- is 79 dBuV QP/66 dBuV average from 0.15 - 5
MHz and for 5 - 30 MHz 73 dBuV QP and 60 dBuVaverage. 79 dBuV is almost 9
mV, 73 dBuV is 4.467 millivolts, 66 dBuV is 2 mV and 60 dBuV is 1 mV. Bear
in mind that average is 63.6 percent of the peak value for a sine wave and
quasi-peak varies with duty cycle; at 100 percent duty cycle, a carrier's
quasi-peak value is the same as peak. It is possible to produce truly
horrible peaks and yet be legal to sell!
If, however, power supplies for the lights in question are not FCC
compliant, or not Class B rated, it is possible the apartment owners and
the people who sold and installed them could be subject to fines. This is
because Part 15 makes it illegal to market a non-compliant device, or a
Class A device into the Class B residential environment. Part 15 fines
have been imposed for exhibiting (marketing) devices that did not work and
could not interfere, because they lacked the requisite labelling and
disclaimers. So it's worth the effort.
Note that I am NOT a lawyer and this is NOT legal advice, just from
experience doing EMC.
QUOTE
Section 15.1 Scope of this Part.
(a) This Part sets out the regulations under which an intentional,
unintentional, or incidental radiator may be operated without an individual
license. It also contains the technical specifications, administrative
requirements and other conditions relating to the marketing of Part 15
devices.
[snip]
(c) Unless specifically exempted, the operation or marketing of an
intentional or unintentional radiator that is not in compliance with the
administrative and technical provisions in this Part, including prior
Commission authorization or verification, as appropriate, is prohibited
under Section 302 of the Communications Act of 1934, as amended, and
Subpart I of Part 2 of this Chapter. The equipment authorization and
verification procedures are detailed in Subpart J of Part 2 of this Chapter.
END QUOTE
and
QUOTE
Section 15.3 Definitions.
(h) Class A digital device. A digital device that is marketed for use in a
commercial, industrial or business environment, exclusive of a device which
is marketed for use by the general public or is intended to be used in the
home.
(i) Class B digital device. A digital device that is marketed for use in a
residential environment notwithstanding use in commercial, business and
industrial environments. Examples of such devices include, but are not
limited to, personal computers, calculators, and similar electronic devices
that are marketed for use by the general public. Note: The responsible
party may also qualify a device intended to be marketed in a commercial,
business or industrial environment as a Class B device, and in fact is
encouraged to do so, provided the device complies with the technical
specifications for a Class B digital device. In the event that a particular
type of device has been found to repeatedly cause harmful interference to
radio communications, the Commission may classify such a digital device as
a Class B digital device, regardless of its intended use.
END QUOTE
Manufacturers spend a lot of effort to get in as Class A; they think this
eliminates any responsibility to fix interference problems. It means
there's a lot of stuff out there putting out millivolts rather than
microvolts. However, it won't hurt to look at the power or control
modules to see if they bear an FCC label.
QUOTE
Section 15.101 Equipment authorization of unintentional radiators.
(a) Except as otherwise exempted in §§ 15.23, 15.103, and 15.113,
unintentional radiators shall be authorized prior to the initiation of
marketing, as follows:
[snip]
Class B external switching power supplies............ Verification
Class A digital devices, peripherals & external switching power
supplies.......................................Verification
END QUOTE
and
QUOTE
Section 15.19 Labelling requirements.
(a) In addition to the requirements in Part 2 of this Chapter, a device
subject to certification or verification shall be labelled as follows:
[snip]
(3) All other devices shall bear the following statement in a conspicuous
location on the device:
This device complies with Part 15 of the FCC Rules. Operation is subject to
the following two conditions: (1) this device may not cause
harmful interference, and (2) this device must accept any interference
received, including interference that may cause undesired operation.
[snip]
(5) When the device is so small or for such use that it is not practicable
to place the statement specified under paragraph (a) of this section on it,
the information required by this paragraph shall be placed in a prominent
location in the instruction manual or pamphlet supplied to the user or,
alternatively, shall be placed on the container in which the device is
marketed. However, the FCC identifier or the unique identifier, as
appropriate, must be displayed on the device.
END QUOTE
It's worth remembering the last sentence of 15.3(i): "In the event that a
particular type of device has been found to repeatedly cause harmful
interference to radio communications, the Commission may classify such a
digital device as a Class B digital device, regardless of its intended use.
"
Worst case, we can petition the FCC to declare a type of device (switch
mode power supplies for small halogen lights) that repeatedly causes
harmful interference to radio communications Class B.
And an idea; why not call the local AM stations and say the apartment
management is keeping people from hearing them?
Cheers,
Cortland
KA5S
> [Original Message]
> From: Kelly Johnson <n6kj.kelly@gmail.com>
> To: <rfi@contesting.com>
> Date: 12/17/2006 7:09:25 PM
> Subject: Re: [RFI] Low voltage lighting solid state "transformers"
>
> ... More importantly, if the device meets the radiation
> limits then the burden of fixing the problem is on the user, not the
> manufacturer. That's the big black hole in Part 15. Manufacturers
> should be required to fix or replace faulty units that cause harmful
> interference OR experience interference from a legally operating
> transmitter. It should be a required part of every warranty.
> Unfortunately, this will never happen.
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