Strange FCC Rules

You may have noticed that all household electronic equipment bears the following statement:

“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.”

Part 1 is self-explanatory. Part 2 has bothered me for a while. Why would rules require a device to be susceptible to harmful interference?

I think it is mostly so that companies cannot make equipment that the Gov’t cannot control. If the manf. created something that would block all signals, then the gov’t could not send jamming signals or controling signals (depending on the device). It is an attempt by the gov’t (FCC) to make sure that they will always be in control.

No pirate radio stations, they can jam them.

They can shut your computer down with a word.


That sounds a little paranoid, but it’s the only explanation I can think of as well. What I was hoping for, however, is a definitive answer.

I too have wondered about this notice.

StrTrkr777’s explanation seems to explain Part ONE, which criminalizes any transmissions FROM the device. Part two is stranger.

My guess is that part two means something like this:

“This is device is not very important, and as devices go, this one has no special privileges. If it goes wacky when you turn on the vacuum cleaner, that’s your tough luck, and you can’t return it to the store claiming it to be defective.”

Any other guesses?

For those who are wondering, I was trying to be paranoid. Who knows why the gov’t puts regulations on products. Maybe because they have nothing better to do.


Perhaps by “… must accept any interference received …” the Feds mean that the device must operate in an EMI (Electro Magnetic Interference) environment. Somewhat like having a drivers license means that you must accept any idiot drivers being on the road with you. You see them, avoid them, ignore them, and go on your way.


A point in every direction is like no point at all

One reason for this rule is if an electrical device happens to interfere with any FCC sanctioned television, radio, etc. broadcasts, then they have the right to prevent it’s use. I worked one summer for the cable company, and this rule was used when a ham radio operator would interfere with cable signals. (not intentionally, usually).

I have emailed dimitri’s question to a 30-year broadcast engineer. Give him a day or two to reply.
If he says to check I will yield to StrTrkr.

dimitri: (2) is pretty much just the “flip side” of (1). In section (1), the FCC is telling electrical and electronic device manufacturers that their products can’t interfere with communications or broadcast signals. Section (2) tells them that they should design their devices so that they will be as “immune” as possible from other devices that aren’t so well designed or maintained.

Sheesh, folks: this is all really very mundane. Paranoia is quite unwarranted.

Basically the second part is a rule that says you have no legal right to tell someone to shut something off or that it’s illegal to operate because it makes your PlayStation stop working.

Both parts combined tell manufacturers to shield their equipment. You can’t build an unintentional transmitter (i.e. ever had a problem listening to 89.9 FM or 90.1 FM in the presence of a 90MHz computer?) and you shouldn’t build something that’s absurdly sensitive to minor radiation (i.e. ever had a 90 MHz computer die because there’s a 90. MHz radio station in the area?)

I think the first part is particularly clever because the word “harmful” is allowed to change over time, so the rule changes automatically as forms of radiation are considered “harmful.”

I had considered the possibility of Part 2 meaning something like what NeedAHobby and others have suggested - that it’s simply a notice to the consumer, informing him that due to the nature of electromagnetic technology, interference is a fact of life.

However, it seems that were someone to shield a device so well that it would not be subject to interference, such a device would be in direct violation of FCC rules!

In considering the violation of the second part, I guess it depends on what they mean by “accept” in “This device must accept any interference received, including interference that may cause undesired operation.” From a product specification standpoint, since the behavior of “accept” is not clearly defined, I would assume that means “handle in an acceptable way,” or “not blow up, catch fire, or fold, spindle, or mutilate the user when exposed to”.

So write the FCC and request changing the phrase to, “This device must not blow up, catch fire, or fold, spindle, or mutilate the user when exposed to any interference received, including interference that may cause undesired operation.”

I think part 2 mainly protects the FCC by making the manufacturers responsible for any harmful effects of any EMI that could have fallen under the FCC regulatory control. The possibility that the FCC may not have foreseen and should have foreseen any past, current or future unregulated EMIs prancing around in ether and getting sued for it is what this part of the regulation is all about.

In a twisted way, this also protects the manufacturer because it is notifying the consumer that there could be unreulated EMIs dancing around that the manufacturer have no control over, therefore not liable for.

Part 1, of course, make sure that no consumer can play with these happy-go-lucky EMIs, even if it is by mistake. In other words, the consumer beware, no body is responsible!

I don’t think you CAN sue the FCC. Other than to reverse an arbitrary or misinformed ruling, that is.

There was some U.S. Supreme Court case a long long time ago which established that, since the U.S. was a “sovereign power”, you couldn’t sue the U.S. for damages unless Congress passed a law allowing you to sue the U.S… Federal laws do permit citizens to sue several U.S. agencies, but not all of them. I know for sure that you can’t sue the IRS, for instance.

I doubt the FCC is one of the sue-able U.S. agencies.

This explaination seems reasonable. Though I would like to also suggest rule 2 could mean:
Even if harmful interference is causing this device to go haywire, see rule #1.

It seems conceavable that under “normal conditions” a device with an amplifier wouldnt cause “harmful interference”, but if your arch-welding right next it… the amp might pick up the signal, amplify it, splatter it all over, etc. greatly accentuating the harmful effects.

At first I took it to mean “must accept any interference received [and keep operating properly]…” but that doesn’t really make sense when the wording of the second part is considered. It may just be a case of bad English. I eagerly await Doug Bowe’s info.

“Accept” is a synonym for “tolerate”. This is clearly the usage the FCC was trying to get across. The language seems very clear to me – I still don’t see the need for unnecessary confusion and complicated speculations (but I suppose it can be fun sometimes).

This is probably right. On the other hand, if interference causes “undesired operation” in a device, I would not say that the device is tolerating that interference. Part 2 then becomes an oxymoron, suggesting that “tolerate” is not the intended meaning of “accept” in this case.

The engineer I am waiting to hear from is installing transmission cables with a crew on top of Mt. Franklin.
A complete post with cites from him may be while in coming.
His short “in the hall” answer is that dimitri is quoting from Section 15 of the rules and it’s a cover-all CYA area.
a)Your device cannot interfere with a government device, but b)a government device can darn well interfere with yours.
Short example he gave: Several weeks ago there was a BIG exercise over at Ft. Bliss.
Our transmitters shouldn’t (and didn’t) interfere with their communications.
On the other hand, if THEIR communications interfered with us–commerical radio, CB, ham, TV, whatever–tough.

Here it is! The engineer left this post!
----------------Section 15------------
The language is accurate and clear to anyone that works with FCC legal
wording. The FCC is required to regulate / govern any device that may
potentially transmit an rf signal. Just like the FAA is required to
regulate anything that flys.

The language was provided to authorize the manufacture and sale of
‘unlicensed’ devices that might potentially cause interference to ‘licensed’
services and devices. With out the language ( and incidentally the required
posting on the device) it would be illegal to manufacture and sell and ANY
unlicensed devices that could potentially transmit rf, thus the language
that makes it possible to design and build an “unlicensed” device.

Licensed devices are protected from interference from other licensed devices
and services AND unlicensed devices.

A really good example of unlicensed devices that are being impacted by
‘licensed’ devices are the medical heart monitors and wireless mics that are
located on the same frequencies as unused TV channels in a given area. With
DTV being implemented those unlicensed (and unprotected) devices are all now
subject to interference from licensed serivces (like DTV). The wording
simply authorizes the manufacture of unlicensed devices and notifies the end
user that if there is an interference problem, with a licensed device or
other unlicensed device, they simply have to accept it. There is no
recourse via traditional FCC complaint. The FCC doesn’t want to be
innundated with thousands of nusiance complaints over unlicensed devices.