I'm in the US. I recently swapped 6 old receptacles on a single circuit out for the tamper-resistant variety. It was a straightforward process--all the boxes except one had a single cable coming in. The only thing remotely challenging was that two had their bottom halves controlled by a wall switch (I did break off the tabs).
Afterwards, I tested each outlet with a meter--all showed 120V hot-to-neutral (actually more like 123-124V), no hot/neutral reversals, and good ground connections. I plugged everything back in and everything seemed to work, and the switches correctly operated the two outlets they were supposed to.
But then I plugged a circuit analyzer into the unswitched half of one of the switched outlets, put it in "voltage drop" mode, and it immediately sizzled and emitted a puff of smoke and the smell of ozone. It could no longer measure voltage drop after that (it could before), but the other functions still worked and said everything was ok. I wrote it off as a bad meter (it was newish and I'm told they're prone to those sorts of failures), and made arrangements to return it.
But a few days later, I pulled out an old computer tower and plugged it into a different (unswitched) outlet on the same circuit, and its power supply immediately sizzled and died too, before I'd even pushed the power button (the 115V/230V switch was in the correct 115V position). Now, this was a dusty 13-year-old tower that had been on the shelf for a couple months, and it's not shocking that its power supply would fail. But given what happened to the circuit tester, I have to wonder if I screwed something up when I replaced the outlets. But I have to emphasize that all the numbers look good, none of the lamps on the circuit ever flicker or get dim (or bright), and that everything else I've plugged in there, including two laptop computers and a vacuum cleaner, has worked fine.
So, is this just a coincidence? Is there any mistake I could have made that would produce these sorts of symptoms? Any tests I should do?
Details from memory:
Old work used "backstab" connections everywhere except in one spot where two wires had to attach to the same terminal; they'd used both the back slot and the corresponding screw there (box #4 below). I moved everything to the screw terminals, adding a pigtail in box #4 to solve that problem.
Box #1: Half-switched single duplex outlet, single wire bundle plus red wire from switch. Attached black wire to top copper terminal, red wire to bottom copper terminal, and broke off the tab in between. Attached white wire to one of the silver terminals (left tab intact here) and green wire to green terminal.
Box #2: Unswitched double duplex, single wire bundle. Attached incoming black and white wires to top copper/silver terminals of receptacle #1. Ran short lengths of black/white wire from bottom terminals of receptacle #1 to copper/silver terminals of receptacle #2. Old work had ground wire hooking around the ground screw on receptacle #1 and then continuing to the ground screw on #2, with insulation stripped off at the two points of contact. I didn't like this, but didn't have any more wire handy, so left it as it was.
Box #3: Unswitched single duplex, single wire bundle. Very simple. Black to copper, white to silver, green to ground.
Box #4: Switched single duplex, two wire bundles plus red wire from switch. This was the most complex one. Used a wire nut to pigtail the two black wires together with a third short length of black wire, and attached the other end of that to the top copper terminal. Attached the red wire to the bottom copper terminal, and broke of the tab in between. Attached the two white wires to the two silver terminals, leaving the tab intact. I actually don't remember what was happening with the grounds, but I think they were already pigtailed like the hots (but perhaps just twisted together instead of in a wirenut).
Box #5, Unswitched single duplex outlet, single wire bundle. Just like #3.