What's the issue with these? They look as safe as any other fuse-less extension cable to me. As long as you have a fuse somewhere in the circuit, what's the problem?

You plug one end into a hot AC outlet. Now the other end has hot 110-120V AC on exposed pins. Touch them and you are in for a bad time.

A normal extension cord like we've all used has a plug at one end and a socket at the other, so you won't get killed by simply mishandling it.

I love this part of the product description:

"It Can Help Protect Your Family And Keep Them Safe"

Right...

Having said that, the longer Product Description With Every Word Capitalized explains the use case somewhat:

You've lost power and it will be likely be out for quite some time. But you had the foresight to have a generator and one of these cords. You plug one end into your generator and the other end into an ordinary wall outlet. Now every outlet on that circuit will be powered from your generator.

However, your normal fuse or circuit breaker will not protect you from an overload on that circuit, because you've just hotwired your generator into the "house" side of the circuit. So, as the description says, you may be able to power your refrigerator and some lights, but overload the circuit and you may burn your house down.

Also be sure to turn off that breaker or remove the fuse on that circuit. Otherwise you will be having some fun when power is restored!

Oh gosh, it gets even better. Check out the reviews on the Amazon listing!

Finally, I would like to thank the parent commenter for asking an honest question. Perhaps it sounded naive to some, but I appreciate a question like that, as it gave several of us a chance to explain the issues around this kind of electrical cord.

That brings a lot of needed context to this image I saw a long time ago.

https://pbs.twimg.com/media/ESHx9kxVAAA9_zi.jpg

For extra fun, there’s absolutely nothing stopping the generator you just plugged in from feeding power back into the electrical grid if you don’t turn the breaker off.

So the repair crew has the lines deenergized to replace that transformer that blew down the block from you except... surprise! they’re still live!

>> Touch them and you are in for a bad time.

Or just very awake. You sissies. I've been buzzed by 230V AC so often... :-)

(Imagine picture of raised hair by van de Graaff generator here)

Someone once handed me one of these when I asked for an extension cord, and I didn't notice. I plugged one end of it in, reached around for the other, and copped 240V AC. Luckily the house had an RCD (mandatory here in Australia), so I just ended up with a very sore arm. I was in a basement alone so it could have been very bad.

Male-to-male cables absolutely should not be made up.

Apparently some people make them for plugging caravans in to external power as a sort of hack.

I’ve always been a bit disappointed that the US never adopted RCD’s at the service panel. I discovered a double-gang light switch box at my house that for some inexplicable reason has a common neutral for lights on two separate circuits, and when replacing one after turning off what should have been the correct breaker I got a nice buzz touching the neutral wire - if the panel had an RCD those lights never would have worked in the first place.

In hindsight it was stupid to not have turned off both circuits anyway, I’m just glad I was wearing sneakers so the shortest path to ground was the junction box itself.

Using a shared neutral for two circuits was a common practice to save on wire. It's allowed as long as the two circuits are connected to different legs/phases of the electrical panel.

More recent versions of the NEC require that the breakers used for both hot legs of such circuits be linked so turning one circuit off also turns off the other.

Common neutrals on residential branch circuits have largely fallen out of favor for new construction due to requirements for GFCI or AFCI protection on most circuits.

For anyone as unfamiliar with the term RCD as I was until now, it is the same thing that in the US we typically call a GFCI or GFI (ground-fault circuit interrupter):

https://en.wikipedia.org/wiki/Residual-current_device

These are usually built into the electrical outlet (or one outlet may provide the GFCI/RCD for several connected outlets). A whole-house RCD as described above would be a wonderful thing.

From personal experience, a GFI-ied house can also be a nightmare. A house can have a lot of outlets. Some of them well-hidden, unused, and long forgotten.

If the “test” button is ever unintentionally pressed, maybe from some furniture or whatever pressing against it, then your whole circuit goes down. But the breaker box shows no fault, and now you get to waste the afternoon inspecting every inch of wall space for an upset outlet.

This is a problem you don’t have when the GFCIs are in the breaker box, though.

Yea. I have three of them for my condo. One for the "wet-rooms" (bath and such), one for the electrical stove in the kitchen, and one for the rest. Though it wasn't so initially. Got upgraded about 10 years ago. Now the breaker box says 400v 63A and I wonder how I ever reasonably could use that here.

You have a condo, so the 400v is because the building is being supplied with three-phase power - 63A gives you a total of 25KW which is certainly a lot, but normal residential service is usually 240V @ 100A because of HVAC needs so it’s really more or less the same.

RCD breakers really are a wonderful thing though, I had my second small fridge knocked out because I had accidentally hit the test button of the outlet near the kitchen sink that the dining room outlet was fed from - having it at the breaker makes it a whole lot less confusing and removes the searching for the protected outlet conundrum.

Depending on where you are in the US GFCI breakers might be required these days in certain scenarios. Dual AFCI/GFCI breakers are certainly available at the hardware store. They're expensive though so it seems most people don't use them unless required to (which is crazy IMO).

Related but different, AFCI breakers are now required where I'm at in bedrooms and similar spaces where you wouldn't expect appliances to be plugged in.

because you plug it in, and the prongs on the other end become live.

Also if you plug the other end into a live circuit, or the circuit subsequently becomes live, you can make it a murder-suicide.