Safer for the operator? Sure. But certainly not for the device, if you're trying to keep it operating. An ATX power supply has 24 pins at 5 different voltage levels (plus any auxilliary power connectors for the GPU and drives, etc...), and motherboards are a lot less tolerant of spikes and transients than the PS on the other side.
Dealing with AC power isn't really that dangerous if you're careful.
We had an electrician of questionable licensing do some minor work for us (replacing some switches and outlets). I asked him to tell me when I should go down to the circuit breaker to turn off the electricity and he told me not to bother. He did all the work with hot current running through the wires. I stayed close enough to be able to tell if I needed to call 911 but no closer while he worked.
I was once working for a small company building electrical equipment. We mostly worked on "medium voltage" equipment, you know 2400 to 69000 VAC.
For one project we had large banks of ultracapacitor in a cabinet. Fully charged it was around 1200 VDC. This thing was in the prototyping stage, and we were testing a control system on a Saturday morning.
So we charge it using a large AC/DC converter, fully charged, everything worked beautifully. We start a discharge cycle converting the DC back to AC. Uh oh, it starts pulling way too much current. Flames start to shoot out of the AC/DC converter. Fuck. BANG. Fuse blown.
We assess the damage... the AC/DC unit is totally shot. And someone (me) is going to have to analyze what caused the failure. Otherwise everything with the capacitor cabinet seems okay, but the thing is still charged to 1090 VDC and the fuse is blown. Check with the mechanical engineer that designed the cabinet. Turns out the fuse can't be changed (can't be accessed) while the cabinet is charged and the cabinet can't be discharged because the fuse is blown. Well that isn't good.
The only thing we could do was discharge it into a load bank (think large toaster) by connecting something directly to the copper busbar live at 1090 VDC. So one of the commissioning guys volunteered. He put on some high voltage gloves, stood on a plastic mat, and connected some jumper cables someone had in their car to the bus bar. He stepped back and someone else threw the switch on the load bank and it discharged without incident.
You would think if you guys were working on those AC voltages, you'd have an arc flash suit on hand and he would have also put on an arc flash suit to do that.
I've done a ton of electrical work for my own benefit over the years and I'm perfectly comfortable doing things like swapping switches with live wires. I've never once had a problem. The one and only time I've fucked up was when I cut a run of romex cable that I thought had been turned off.
Lesson learned: electrical wiring is like a gun. Always treat it like it's on, and if you have to do something would be unsafe if the wiring is energized, make damn sure it's de-energized before proceeding. When you're working in that mindset already anyway, flipping the breaker for something as simple as swapping a switch/outlet hardly has any benefit.
I apprenticed with my Dad. The first two rules he taught me have stuck with my my whole life:
1) Treat every wire as if it was hot. Even if you know it's not.
2) A good electrical connection must first have a good physical connection.
Not sure why that second rule sticks with me :) but there has been more than one occasion when I'm fairly sure the first rule has saved me from a bad shock. And you're right - treating the wires as if hot means you can actually work with hot wires for a lot of simple things.
The second rule is a great one that so many people doing their own work miss.
The wire nut is only there to stop the wires loosening over time and provide some basic insulation. It is not there to actually attach the wires. When you twist your wires together, they should be attached well enough on their own that you'd be comfortable throwing a piece of electrical tape over them to stop them shorting to the box and leaving it as-is (but don't do that). If the only thing keeping them together is the wire nut and you being very gentle when you manipulate them back into the box, they're not actually connected.
The poor physical connection creates a poor electrical connection. A poor electrical connection has resistance which creates heat. Heat creates fires. Even better after a few years when enough traffic has driven past your house and enough people have moved around inside of it and the wires have wiggled to just barely in contact so occasionally when someone walks down the hallway the lights will all flicker as the wires create some pretty electrical arc light shows, adding carbon buildup to the wires and further increasing the resistance and heat concentrated in the one tiny point of the copper where they're still sometimes connected.
No reason at all for this rant. Definitely not a real example at all. Definitely didn't waste an afternoon with a toner, a drill with a pilot bit, and a borescope to hunt down the six octagon boxes someone had sealed into the basement ceiling hiding away some of the shoddiest wiring I'd ever seen. Nope.
100% confirm on the wire nut thing. It's possible to get a good twisted connection with a wire-nut without pre-twisting, but conditions have to be just right, and must result in a properly twisted wire pair in the end, or it's just trouble waiting to happen.
One packet of wire nuts I bought came with a drill bit made to twist them on. I found it works way better than twisting the wires by hand, it creates a tight twist that's very hard to undo.
This makes me feel bad. As a kid, I remember holding light switches at just the right point to hear the buzzing (arcing)? inside. At least if the contacts were carbonizing, there wasn’t a lot flowing through them closed.
I'm not a nut that does everything with the power on--I kill any branch I'm working on and double and triple check with a non-contact voltage detector before I stick my fingers into anything (which saved my bacon the one time when the hot from a different branch of the same phase ended up connected to a neutral wire for a plug with no connected ground leaving it showing 0V on a multimeter in any configuration and still being live with the breaker off; that house was a mess). However our current dwelling has no main cut-off for the power. If we wanted to turn off power to the panel we'd need to get the power company out to pull the meter from the socket.
In a mostly full panel the bus bars are pretty much completely covered by the breakers anyway. You'd have to work pretty hard to come in contact with them. And the wires you're working with (besides the ground) are insulated anyway so no issue if they brush up against something.
The only thing that's _slightly_ butthole puckering is chasing the uninsulated ground wire through the panel down to the neutral bus.
And yeah, done without gloves because weighing "safety when I make a mistake" versus "greater dexterity so I'm much less likely to make a mistake" I prefer the latter. The protection is rubber soled shoes and keeping one hand tied behind my back so the electricity has no path through me.
Ha, that's nothing. I once watched a stubborn guy replace the bus bars in the input panel of a house. He did wear rubber gloves and boots and stand on a plastic stool. But, this is a kind of job where you are operating a socket wrench on the clamps holding down the bare ends of the thick direct-burial power cables, then wrestling the ends of the cable out of the way to unscrew and remove the bus-work from the panel chassis.
He did this without notifying the power company, so those supply lines were hot with 240V residential service. The weather shifted and a light mist started falling before he was done. Like another poster above, I was thinking I need to be ready to call 911, but wanting to be far enough away not to be hit by splattering metal or any surprise voltage gradients in the soil.
I accidentally replaced an outlet and added a switch to a circuit that was still energized. I had turned off the wrong breaker, and failed to confirm it before I started work.
But, careful work habits and some tools that happened to be insulated anyway, meant that I was never bridging two different potentials. The job went flawlessly and I only noticed when I plugged the outlet tester into it at the end, expecting to go turn the breaker on and come back and look at the lights... but the lights were already lit up.
Working on hot wires is no problem. Ground wires scare me and I'll turn off the main breaker before I touch them. You can never be sure what ground is really at.
In more than a few dilapidated rentals I've been in...
Ground is ... all the metal bits in the bathroom and there's earth leakage happening somewhere.
The safe work procedure is then: get the shower to the desired pressure and temperature before you get in / while you're still wearing your shoes then try not to touch the taps while you're in there.
But don't tell the guests cos hearing them yell "FUUUUCK!" is amusing.
Bonus points if they pass out from the shock and knock their head on the way down.
Splicing into the many wires that is an atx+12v power connector, between the output of the power supply and the motherboard is way more fiddly than just dealing with the hot and neutral on an ordinary $5 PC power cord. You could also never be certain what weird ziptie and cable management system (or lack thereof) might exist in a home built x86 PC case, or if there's any room for hands to work at all...
I think the thing I saw is also meant to deal equally well with a commodity x86 PC built from parts, or an Intel NUC size thing, or a corporate desktop machine with proprietary internal wiring like a slimline Dell, Lenovo, HP, etc.
