[LeifCarrotson]

Regarding your first point, the relay has 2,000V of coil-to-contact isolation:

https://omronfs.omron.com/en_US/ecb/products/pdf/en-g5le.pdf

Though it does look like the clearance/creepage distances on the PCB to the low-voltage ground plane are not any wider than 2mm or so, which is acceptable for 120VAC, but not acceptable for 240VAC per IPC9592.

I wouldn't worry about sticking this in an enclosure and using it to turn a light on and off, but I wouldn't want to be handling it while it was live, either!

Regarding FCC/UL certification, a product is exempt from FCC certification requirements if it's "A digital device used exclusively as industrial, commercial, or medical test equipment", which most development boards are. I've got some dev boards from Microchip on my bench right now which aren't FCC or UL listed, either.

[tripletao]

A digital device is defined as:

> (k) Digital device. (Previously defined as a computing device). An unintentional radiator (device or system) that generates and uses timing signals or pulses at a rate in excess of 9,000 pulses (cycles) per second and uses digital techniques; ...

https://www.govinfo.gov/content/pkg/CFR-2009-title47-vol1/pd...

This has Wi-Fi, so it's an intentional radiator, so it's not a digital device. I believe this product would be technically noncompliant if not certified, though lots of stuff like this gets sold and I've never heard of any enforcement action.

Their best counterargument would be that it's a component and not a self-contained product. That seems true for many dev boards but not particularly true for this one. Since the practical risk of interference is extremely low, I'd guess the FCC is happy to leave this grey for now.

[R0b0t1]

Test and measurement supersedes intentional emission. If it were the other way no development boards would get sold, especially necessary things like low volume engineering samples. Should a one-off need certification before it can be transferred to the company that contracted the work to build it? No.

If you have never sought certification know that it is quite expensive.

What seems to matter the most is if anyone actually notices interference, and if they do how widely the device ended up being sold. If a test and measure product starts making it into everybody's house eyebrows will be raised.

If you misuse a test and measurement device and generate interference it is typically on you.

[tripletao]

> Test and measurement supersedes intentional emission.

On what authority are you claiming this? The language LeifCarrotson quoted refers only to digital devices, and the language I quoted above says plainly that a digital device must be an unintentional radiator.

To be clear, I believe selling their dev board is fine, but it's fine in the same way that driving 60 mph in a 55 zone is fine. Anyone selling an intentional radiator dev board that could reasonably be considered to be a complete device in itself is taking a small risk of FCC action, especially if (as here) they're pushing the limits of "dev board". Note that the Raspberry Pi developers do seem to get certs.

https://www.raspberrypi.org/documentation/hardware/raspberry...

[R0b0t1]

On what authority are you claiming otherwise?

My opinion comes from experience and getting things certified but also common sense and observing enforcement patterns (the latter of which is most important until they overstep and get challenged).

Go back to my example: Does a one-off product need to be certified to be transferred to the people that paid for it? Keep in mind, best case, this will add a roughly >$10k fixed cost to the sticker price.

It's a general principle in common law that the law makes sense. The popular, sophomoric, and extremely conservative interpretation of the FCC rules makes no sense by way of being extremely costly for no discernible benefit, either to the seller, the buyer, or the economy at large.

[tripletao]

I am claiming this on the authority of the text of the regulations. The USA is a nation of laws, and those regulations have the power of law. If it came to that, a judge isn't going to disregard them just because you think they're too expensive. If you think otherwise, can you provide case law to support your view?

By law, that one-off intentional radiator absolutely does need to be certified. The FCC's enforcement priorities will be different depending whether that product is a little 2.4 GHz radio or a television transmitter, but their enforcement discretion doesn't change the law. Anyone who wants to be compliant needs to pay for the testing (or use a certified module, which is often easy and cheap; I've done that several times myself).

Lots of people disregard lots of laws because they're too expensive to comply with. Most of them get away with it, and a few of them get nasty surprises. I believe that I've given both the correct legal advice and a correct description of typical (not fully legal) practice. It's not helpful to conflate the two.

[R0b0t1]

The text of the law matters not as much as what the law was intended to do. In any case, by saying the one off needs certified you've gone off into la-la land; any reasonable person classifies it as a test/measurement device and gets on with their life.

[antoniuschan99]

If it’s sold as a kit(eg. Devboard) or battery powered it doesn’t need to be certified. You also can get pre-certified boards, the wroom-02 being the pre-certified esp8266.

[R0b0t1]

I've seen certified development boards also, but what most don't realize is you can't combine certified parts to make a certified product. So depending on your product there is literally no benefit to getting it certified.

There are things that are battery powered that need to be certified and things that are not kits that don't need to be, though, so I'm not sure I can agree with that wording.

[tripletao]

I think battery-powered unintentional radiators can sometimes avoid testing, but battery-powered intentional radiators definitely don't. The statement about kits is also wrong, per pdabbadabba's comment below.

An intentional radiator module can get a module certification. In that case the final system still needs verification (the same kind of testing that an unintentional radiator gets), but doesn't need certification. When you see a label on the outer device that says "Contains FCC ID XXX-XXXX", that's the module's ID.

https://apps.fcc.gov/oetcf/kdb/forms/FTSSearchResultPage.cfm...

[antoniuschan99]

Verification is Declaration of Conformity (DOC)? You can either get a Declaration of Conformity from the lab or just sign it yourself. But in the chance you get audited and it doesn't function how you said it would then you'd get in trouble

[tripletao]

And I'm responding again to note that I think I interpreted "kit" wrong. I was thinking "kit" as in § 15.23, which gives an exemption for stuff you build yourself but not stuff you build from kits.

But 47 CFR § 2.803 gives an exemption for "evaluation kits". I don't think that clearly covers boards used primarily as single-board computers (and not genuinely for evaluation), and I'd guess that's why the Pi developers got certs for their boards. I believe it's the best argument that this board wouldn't need certification (or verification), though.