I never knew that USB-C extensions are not allowed for a reason

If you want a more detailed explanation, USB-C is a small connector that was designed primarily for data transfer, extended power range delivery (240w) was essentially hacked on to the standard. Electricity arcing between the contacts on the connector is the biggest challenge with this hack, since the contacts are small and very close together, which could burn out the circuit board and start fires. For EPR to work safely, there needs to be a lot of extra components on the circuit board/female connector side, which there simply isn't enough space for on an f2m extension cable.

As for why USB-C cables are so short, it's simply a matter of physics, carrying high speed data over larger distances would result in higher losses and requires thicker conductors and more shielding, which is why you don't see USB4 Gen3 cables over 1 meter unless they are optical, and longer "charging cables" are only rated at USB 2.0 speeds, because more often than not they don't even have the USB 3.x data pins on their connector.

You are a brilliant woman of many talents, Margot Robbie!
- That's esteemed Academy Award nominated character actress Margot Robbie to you!
  
  Also, thank you.
It's amazing for a "standard" that there can be so many non-standard ways to do it. Your explanation is great and just reminded me that cable tester tools are a really good idea to have at home. There was one in Kickstarter earlier this year, I think, that was a really smart idea. I don't recall what it was nqmed though. Maybe you have heard of it? I'll see if I can find it.

Regardless, there are some devices that really need a specific type of usb-c cable to function properly and/or not burn the circuitry. (i.e. Nintendo Switch, the original release model (though, they may have fixed it in later hardware revisions))

Edit: Found it! That cable tester that I was referring to was called the BLE CaberQU. I think it is a really neat idea.
- Nice! I’ve wanted a tool exactly like that many times. I’ll back it and see.
  
  The closest I could find before were essentially pin to pin continuity checkers, which are useful for telling if a cable is PD only, 2.0 vs 3.x, or has a line break, but most of those can be eyeballed, otherwise metered. So these just checkers just add precision and speed to something you already know how to do.
  
  The runner ups were the (now ubiquitous) inline inductive energy trackers, because they can tell you a bit more about the gauge of the wires in the cable which can be important, especially high amperage 5v like pi 4.B
  
  But to test quality of shielding for high rate data transfer, DP and PCI-E tunneling, etc., the only option was manually user testing with adequately powerful devices.
I have this cable: https://www.spigen.com/products/arcwire-usb-c-to-usb-c-cable-pb2202

It's 2 meters long, 240 watts and supports Thunderbolt 4/USB 4 (40 gbps).

I couldn't test the 240 watts charging as I don't have any device pulling more than 100 watts, but the Thunderbolt 4 part definitely works.

Apple sells a 3 meter Thunderbolt 4 cable (albeit limited to 100 watts of power) that isn't optical either (I think there's some special circuitry in the plugs though).
- You're right. Those are active cables which I forgot to mention earlier that have special circuits that amplify signals, but are also a lot more expensive as a result.
- $90 for a cable and it’s not even braided is wild to me.
I don't seem to be able to upvote this twice.
- You could always buy more copies of "Barbie" on Blu-ray for Christmas.
  
  Just saying.
I'm glad someone is smart cause I sure ain't
Nice explanation, thanks!
It's a great explanation. However you have some pretty egregious use of commas that made it a lot more confusing. I had to read it over multiple times to fully understand.

It may seem like nitpicking but these subtle issues end up making it harder to comprehend and overall results in more time and effort for everyone you're trying to inform.
- You know you explained a topic pretty damn accurately when the Stranger On The Internet can only use the good ol' "too many commas'" argument to bring you down.
- Didn't have any issues reading it. Come off it
- Some languages have a very different usage of comas. Maybe OP's mother tongue is one of those

Anybody care to sum this up for people who can’t watch videos?

So a standard cable needs to be chipped to show its rating to the device, its not that the device can pull what it wants or can get, but the cable itself tells it what it can supply. Extension cables can’t do that, because it doesn’t know what it’s plugged into, and that would be if they even bothered to put a chip in. They instead piggy back off the chip for the main cable. The problem comes when you you have a 240 watt cable hooked up to a cheap 120 watt cable, with the device being told it can push 240, and starts to super heat the extension cable
- Brilliant thanks
  
  5 sentences that inexplicably need a 9 minute video to say
  
  Fuck YouTube
- This sounds solvable, doesn't it? Have the extension cable have a chip saying it can do X at maximum, then compare with whatever is to be extended and communicate the minimum of both upstream. Might not become a sleek cable-like design, but would extend the 240W cable with the extender safely staying at 120W
- Soon on Amazon..
  
  1m USB-C CABLE HEATER!! 0.99c
  
  ($5.99 shipping)
- Well I'm glad I know that now.
- Correct, except for your example. Firstly, 120 watt USB c cables don't exist, only 60w, 100w, 140w and 240w. And only plugging in a 100w or higher cable into a 60w extension would be dangerous, since it would allow drawing 5 amps on a cable over an extension only designed for 3 amps. However, as soon as your extension is rated for 100w it is completely safe to use with any USB c cable, even those rated for 240w, as those only operate at a higher voltage but still only allow 5 amps max.
  
  I have also never seen an USB C extension cable rated for less than 100w, so this is kind of a moot point. If 60w usb c extensions exist somewhere, they would indeed be dangerous, but I have never come across one
- Pretty much this, thanks for the summary
- Interesting, I'd never trust any USB cable to push anywhere near 100 watts anyway haha good god, the most I ever do is maybe 20w at 5v.
  
  I'll keep that in mind when buying cables in the future though this is very useful info!
- How did we possibly survive with entirely dumb power chords?
Going to take a wild guess and say the same reason you shouldn’t chain extension cords. USB can carry over 200w these days.
- the same reason you shouldn’t chain extension cords.
  
  what if I don't know that either
- Chaining regular extension cords isn't a problem by itself, connecting too many things in parallel and exceeding the rated max is a problem (and chaining extension cords "just" increase the risk that ordinary people will decide to connect more than they should, especially because the lowest rated cable in the chain sets the total limit)
- Yeah, I think in this case there's a lot more tiny conductors sharing what can add up to pretty high current loads on PD connections. Adding extra connectors adding resistance to low (5-20v) voltage high current connections is adding an extra failure point and increasing resistance on the whole cable run.
  
  Not inherently unsafe, but just not a good idea to promote because you know someone will try to run a 200w charging cable for 30m with like 5 connected cables.
Extensions aren't part of the official spec, so they aren't actually certified as proper USB-C.

Same risks as any other janky no-name gear you see online, even if it SAYS it's rated for a specific throughput or power rating, that may not be the case.
This is what AI says about this video:

The video is about the dangers of using USB-C extension cords. The narrator explains that USB-C extension cords are not officially certified by the USB Implementers Forum, which means that they are not guaranteed to be safe or reliable. He also explains that USB-C extension cords can be dangerous because they can overload the power supply of the device that they are connected to. This can cause the device to overheat and even catch fire. The narrator recommends that people avoid using USB-C extension cords altogether. Here are some of the specific dangers of using USB-C extension cords:

They can overload the power supply of the device that they are connected to.

They can cause the device to overheat and even catch fire.

They can degrade the performance of the device.

They can be unreliable.

The narrator also explains that some USB-C extension cords have a label that says "USB 2.0 low speed devices can only work with one side of the ultra high rate extension cables interface." This means that the USB 2.0 connection is only available on one side of the cable. This can be a problem if you need to connect a USB 2.0 device to the cable.

The narrator recommends that people avoid using USB-C extension cords altogether. If you must use one, he recommends that you use a high-quality cable from a reputable manufacturer. You should also make sure that the cable is rated for the power requirements of the device that you are connecting to it. Overall, this video is a helpful resource for anyone who is considering using a USB-C extension cord. It provides important information about the dangers of using these cables and how to avoid them.
- As always AI doesn't quite get it. One of the main points is that it could catch on fire and burn down your house. Plus you'll run into other problems as well. You're not supposed to buy extensions for USB. Buy a longer cable instead.
- You're a bold one. Lemmy hates videos and AI both.
- The AI got most of it vaguely right, but unsurprisingly a lot seems to go above its head. Kinda like reading a shitty tech journalist writing about something they don't understand at all.
- The risk isn't usually the device you connect a bad cable to (they have internal limiters), it's the cable itself. You can easily overload a cable if the extension cord can't signal the lower limit if it's own rating and the other cable's rating.
  
  The USB 2 part is also misleading.

I'll have you know that I've been using a 2m extension on my deck power supply for a while and haven't had any fires to speak of. Almost none actually.

Almost none so not zero?
- thats_the_joke.gif

Usually if a thing is not allowed, there is a good reason for it. Unfortunately many people seem to ignore that because they don't know or understand the reason.

USB-C somehow managed to be the worst "standard." Hopefully the next big USB port doesn't allow for so much variance. I don't see why a specific wattage and data transfer rate isn't included in the specification. I can scarcely believe they managed to standardize it so well that I can plug the wrong cord into a port and break something.

Per the video, the usb-c connector on the cable has a chip that communicates the maximum current that it can safely pass. By plugging it into a lesser rated usb extension cable, that assertion is now wrong, potentially dangerously wrong if enough current is sent that the wires in the extension overheat.

Technically extension cables were not part of the original USB spec, either, but that did not prevent oodles of them from appearing pretty much instantly. They solved a problem, there was a need, and thus they happened.

I.e. there never was supposed to be any such thing as a passive male USB-A to female USB-A cable, and yet pretty much every little MP3 player from 2001 to about 2005 came with one regardless.

Seems negligent to not include extension cables in the spec. Lots of hubs have too short of cables, or one needs to expose a plug somewhere other than where the PC is.

True, although shady Amazon sellers will probably still sell you a fire hazard cord that isn’t to spec.
In theory the hub should be active and participate in the power negotiations
You just get a longer USB-C cable.
- A lot of hubs have non detachable cables.

I never wondered about this, but it makes sense now. Off topic but man, the dry mouth noises he makes inbetween sentences are driving me crazy…

Yeah after looking into it it totally makes sense to me.

Off topic but you user name is the bestos.

How does this apply to a usb-c-to-headphone-port adapter, if at all? If someone's using one to regain access to a 3.5mm audio jack, are any risks posed?

I have a 240W extension from AliExpress, used with a 120W power for my laptop, it never gets hot even when using 100+W

Because you made sure the cable is rated for more than what you're using it for. The problem is when somebody doesn't do that. A 60W cable hooked up to a 120W power supply, for example.
- My highest charger is 65W, that's enough.

don't wanna watch anything rn but boosted for later