Pretty much everyone that owns an RV (in the US) has an adapter that converts the 14-50P (50 amp!) plug on the RV to a 5-15P that can be plugged into common household sockets. You can't run the A/C without popping a breaker but it'll keep the fridge and lights on.
You say this like it's somehow going to generate 12000 watts, or that somehow having an overbuilt cable is dangerous? Yes, the connector is way overbuilt for running 15amp 120v loads, but that's a good thing. You don't want the connector to be the weakest link.
I'm not sure why you think wattage numbers are more relevant than amperage numbers? Amps are what heat the cable and blow breakers.
Unless it's fused, absolutely nothing about a cable or connector stops you from drawing excessive amperage through it. You use splitters probably every day, and every one of those receptacles is capable of drawing full amperage. If you draw too much you pop the breaker in the panel. The breaker must always be rated lower than the wiring attached to it. Everyone with an old house who has tried to run the microwave, toaster, and fridge at the same time has experienced this.
14-50 plugs are more interesting than all this because they're two hots, a neutral, and a ground. If you adapt it to 120v shore power (with a 5-15 plug) you are using split phase power, so one of the hots will be dead. In theory you could draw 50 amps of 120v through that cable, but the box you're plugging into will pop the circuit long before then. Also, this is why your rooftop A/C doesn't work when plugged into 120v shore power - rooftop air conditioners are usually 240v appliances.
I could point to a giant copper rod being used to carry 15 amps and exclaim “you know that’s a 5 megawatt connector, right?” and it would be the same as what you are doing here.
It doesn’t matter what the potential max capacity of something you plug in is. The breakers on the supply are the limiting factor (they should trip before anything down-line exceeds service).
A toaster has a super high max capacity when you throw it in the bathtub. Doesn’t mean plugging in a toaster is dangerous.
Not true. Breakers are most definitely intended to protect against overcurrent situations regardless of whether it's user or equipment caused. (For example, unintentionally plugging 30 amps of kitchen appliances into a single 20 amp circuit. Don't ask how I know.)
That being said, you should never intentionally rely on a safety feature to cut you out - they exist as a backup in case you screw up. The 14-50P to 5-15P adapter referred to by GP is an example of "I know what I'm doing". Just be sure to double check that you really do.
Edit: Also, consider that if you're in a jurisdiction where it's legal to have a 15 amp receptacle on a 20 amp circuit (many places in the US unfortunately) then a cable like this could allow you to draw a sustained current above what the receptacle is rated for but below what would trip the breaker. That's a fire hazard.
"Edit: Also, consider that if you're in a jurisdiction where it's legal to have a 15 amp receptacle on a 20 amp circuit"
15amp receptacles sold in the US are 20 amp passthrough.
So it is common practice and completely reasonable and safe to put 15amp outlet receptacles on a 20amp circuit because the 15amp receptacle cannot accept a physical 20amp plug.
It is NEC Compliant unless the receptacle is the only receptacle in the 20amp circuit - see "210.21 Outlet Devices".
I knew many of them were rated to 20 amps in spite of the form factor but I didn't realize they all were. TIL.
In that case I guess the cable that triggered the article in the first place is no more dangerous than (for example) the 8 receptacles in my bedroom, all on the same circuit (15 amp IIRC). It's a complete non-issue.
Edit: Are the plug and cable guaranteed to be able to handle 20 amps though? From the pictures in the article, it appears someone spliced a 20 amp receptacle onto a typical (maybe not even 15 amp?) PC power cord.
Right, and you SHOULDN'T use a 20A plug with this 15A receptacle, even though the circuit itself is rated at 20A.
You CAN have a hypothetical 5A plug on a hypothetical 50A circuit. The plug is instructive to the user NOT to pass more than 5A through it, and since the circuit is rated at max 50A, it will not cause a fire at 5A from the abiding user.
In this RV case, you are putting a hypothetical {30,50}A plug on a {15,20}A circuit (VERY BAD!) using this unsafe adapter. Your RV can EASILY exceed the maximum rated amps through this plug (since that is how it is DESIGNED -- with a special plug to set this high-current expectation which shouldn't be intentionally defeated to protect against this user "stupidity") and it CAN and WILL start a fire if someone uses this dangerous adapter, the AC kicks on, and the breaker fails or is not installed properly.
This situation is analogous to cheater plugs. I used a cheater plug with a Macbook Pro in a house with only two-prong outlets, and the aluminium shell felt tingly, but the house electrical system and the circuit design of the laptop motherboard, the chassis design, and SMPS in the charger still DO have other ways of protecting my life from electocution by preventing the chassis from unexpectedly shorting with AC line voltage, even without a proper ground. If these fail, I am dead. Regardless, I was admittedly an idiot for circumventing one safety system to intentionally fallback on others, which weren't necessarily designed to protect against my own idiocy since the assumption was that there is a proper ground.
* FWIW, I have friends in my hometown that are electricians, I helped my dad (properly) wire our basement, and I have an electrical engineering degree myself.
>"you should never intentionally rely on a safety feature to cut you out - they exist as a backup in case you screw up"
I've had to use core drills with inline (inbuilt) RCDs while hanging off rope. Those things draw ludicrous current, and are water lubricated with open thermal ventilation for the motor. It's a given that they trip out.
Unfortunately, as soon as a safety feature is regarded as reliable, it's incorporated into standard operating procedures. See Erlang for a well executed version of this idea!
"That being said, you should never intentionally rely on a safety feature to cut you out - they exist as a backup in case you screw up"
Right, that was my point. Of course, a user-induced intentional overcurrent situation will cause the breaker to flip.
However, to my original point, thoughtlessly relying on a backup safety feature in this case to protect against intentional cases is something that engineers working on the Therac-25 cancer treatment radiation therapy machine did, which ended up killing several people.
The software could be set by the user in the UI to enter a bad state where the high power radiation beam was not collimated (it ALWAYS should be diffused in this high power mode). The software was left this way because there was a hardware interlock to protect against this bad state.
Then, the hardware interlocks that were thoughtlessly removed in the new hardware release (without changing the software code), causing a lot of people to be unintentionally irradiated with deadly doses -- since the engineers originally relied on the "breaker" being there, and then it was removed and/or did not always function properly.
You can look at pilot safety procedures and checks to see how this mentality is properly put into practice. Nothing is taken for granted.
I don't believe this is up for discussion: the circuit breaker is a device that is designed and used to protect a circuit against fault conditions. That's the whole point of their use: if a fault condition is detected, the circuit breaker breaks the circuit to about the fault to propagate or damage the circuit and/or any device connected to it.
The breaker, not the connector, provides safety.