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Comment by TIPSIO | Hacker News Reader

Really interesting...

What are people doing with their lights where this would ever come up though?

Edit: From reddit, a use case is found [1]:

> They’re actually used my law enforcement whenever they do a raid and seize a computer. If they turn the computer off, they’ll have to try and get past a password. And if the hard drive is encrypted, they’re basically SOL.

> This can be a real issue for things like drug dealers or CP busts, where they need to transport the computer for analysis, but can’t turn it off. So they roll in a specially designed power bank, plug it into the computer’s power strip, then unplug the power strip from the wall. The power bank keeps the strip hot while they transport it.

[1] https://www.reddit.com/r/livesound/comments/am6308/one_of_my...

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Holiday lights are the main scenario (which is why these signs are often seasonal). Someone will spend hours stringing up lights only to find that they strung backwards with the female end dangling near their desired outlet.

USB cables / “plug & play” have made this more confusing for those with no understanding of electricity; nor do we as a society routinely educate children (or adults) on basic electrical responsibility.

Christmas lights often have a plug with prongs at one of the cable, and a socket at the other end. This way you can make a super-long one by just plugging one into the other.

I suspect that someone accidentally just started with the wrong end, and ended up with the plug with prongs at the far end, and the socket at the end by the electrical socket.

You hang up two strings of lights outside your house. Usually each string plugs into the previous string and it all works.

But if you get one string backwards instead of having a male and female connector to hook them together you have two males or two females.

Taking down and putting up a long string of lights again is a huge hassle. But if you could just buy this one little cable…

Funny seeing the /r/livesound link.

Worked in live entertainment for a while. One cable we would use a lot is called a 'two-fer', it has one male and that splits to two female ends (so you can plug two fixtures into one outlet or dimmer). There also exists a 'suicide two-fer' that is the opposite, you can imagine why it has that name.

I believe I've also seen some 'suicide' cable setups when we needed to make multi-phase power for a motor controller by using different 120v sources. Can't remember the exact cabling of that but someone did end up grabbing a hot male end in that process and got a nice tickle.

Suicide cable joins two 120v (from different phases) to a 208v. Most high powered lighting fixtures require 208. Super illegal, but often facilities do not have the correct electrical setup and people use this to get around it. I almost got cooked but one of those when a stagehand unplugged it without waiting till power was shut off. Contacted and electrified the whole truss.

Back feeding power from a generator through a receptacle rather than a proper panel interlock.

Thats why I made one. I've upgraded now to a proper panel setup for my generator, but it was a quick and simple solution in the moment.

For anyone who doesn’t see why this is a bad idea:

If you plug your generator in like this, you can backfeed the step-down transformers in your neighborhood, which then step up the voltage from your generator and energize your local utility lines with potentially several thousand volts.

This can be a nasty surprise for utility workers trying to restore power to what they think are de-energized wires.

In Florida there are specific legal penalties for injury from this, due to prolific generator use. The simple solution is to turn off the main breaker before plugging in the generator to the home/building. Interlock kits [1] are widely available and can be used with a secondary breaker that an auxiliary male plug can feed.

[1] https://interlockkit.com/

No, you won't. This myth needs to die; at least you didn't include the claim that "dozens" of line workers have been killed by this (they haven't.)

First off: line workers don't touch anything unless they've verified with testing equipment that it isn't live and/or they're using something like hotsticks. Anything they actually put hands on is grounded first.

Second: if power is out, your generator would be connected to everything downstream of the point of isolation which means the main breaker in your house is effectively connected to a near-zero-ohm shunt. Your generator likely cannot power even one or two full households worth of surge load, much less an entire neighborhood. Said generator would immediately bog down, and also pop its breaker.

Stop talking about things you know nothing about.

Only if you neglect to trip the main breaker.

It gets worse: in BC, the local lines lead back to a substation, and from there to the switching yard, by which point tens of millions of volts backfeed into the grid that connects to the WAC Bennett or Revelstoke dams, causing them to run backward, sucking all the water upriver and absolutely decimating the salmon population.

So just don’t use the cheater cords. Save the fish, save the planet, save your fingers.

This is bullshit. Having more volts does not mean your 10kw generator is going to spin a dam backwards.

I think it was a joke.

Tell that to the fish, buddy, tell it to the fish.

Oh, wait, you can’t because they’re all dead now!

Now stick that in your pipe and smoke it.

Mmmm. Smoked salmon.

Suicide cords are not that dangerous when used by a professional. But when used by somebody not respectful and knowledgeable they become quite dangerous. The catch is that 95% of professionals would find another way to do it.

As far as the police example that can be safer than you think. The power supply can be set to not apply power to the plug end until it senses power or you manually hit a switch. But you still have the safety issue of the power strip's end. This should be alleviated by turning off the strip but I would still cover it personally

the 5 percent of professionals who insist on doing things the bad way deserve the consequences and subsequent removal of previously applied "professional" status.

I repair homes for a living and the amount of stuff I've found that's wrong which has presumably been done by a professional is staggering.

The house I'm currently working at, I'm replacing all the flooring, most of the sub floor, some of the walls, and more. I'll have an electrician come in soon and do some work to fix the electrical. It's a metal roof and they did a real good job installing it except they apparently ran out of the proper screws and used incorrect screws to finish the job. The proper screws to attach a metal roof have a gasket so that water can't get in through the screw hole.

Do not use deck screws to attach a metal roof or you'll be paying someone like me a lot of money later on.

> I repair homes for a living and the amount of stuff I've found that's wrong which has presumably been done by a professional is staggering.

That’s because the vast majority of actual skilled professional tradespeople work in commercial and industrial construction, the talent level for residential construction is not very high. There’s also a lot more oversight on commercial and industrial projects (engineer/architect/owner’s representative/construction coordinator) that catches a lot of laziness issues like the one you noted in your post. Commercial and industrial customers expect much better warranty terms than residential customers and it’s not as easy to cycle through a series of corporations on the commercial/industrial side since some opportunities require company history and experience to qualify for even working on a project, leading to contractors ensuring their work is done correctly, since they’re on the hook for repairs down the line.

I know there are skilled people that work in residential construction, but on average the skill level is much higher for commercial and industrial.

I may be biased as I work for a commercial/industrial contractor that uses union labor.

I'm not saying law enforcement never does it, but that sounds like a very bad idea. Your power bank will be out of phase with the grid, and both will be feeding into eachother, which can cause all sorts of problems if I recall my classes properly.

There's a device for doing that properly that automatically detects the appropriate moment for changeover and does it near instantly. It's still quite dangerous. https://wiebetech.com/products/hotplug-field-kit/

> plug it into the computer’s power strip, then unplug the power strip from the wall

For additional opsec, plug your computer directly into wall socket? That is new to me but interesting nonetheless.

Wire it permanently to the house wiring.

Add a trembler switch to the internal power supply.

Depends on your country's wall outlet designs. In the US it would be pretty easy to partially remove the plug from the wall outlet, exposing the bare prongs without disconnecting them from the outlet.

Then you just supply A/C power of your own before unplugging fully from the wall outlet.

Interesting - surely then one would wire the faceplate in a way that it would disable the circuit should it be removed.

I think it would better and much safer to change your PC so that it shuts off if the PC is moved. Offhand, you could probably wire a relay into the reset pins on your motherboard, and use an ESP32 to trigger the connection based on an accelerometer or pressure sensor on the bottom of the PC.

I think there are some low-tech solutions that work as well, but I don't know them off-hand. If you wanted to go that route, you should check out the Harvey's Casino Bomb. That guy had layers upon layers of triggers that would probably work just as well for preventing tampering with a PC.

That would keep the meddling to low-voltage stuff that won't kill someone or start a house fire if it doesn't work correctly. Messing with mains voltage seems dangerous and unnecessary since most of the PC runs on low voltage.

They have a strand of lights with a male and a female end, and they have strung them incorrectly in some difficult to change way so that the female end is near the outlet, and they don't want to move them.

or the have a bunch of lights daisy chained together and have run one string backwards.

Hung two strands of holiday lights in opposite directions.

If they're specially designed, they should have a specialized cable..

cops doing cop stuff. best and the brightest members of society, right?

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