UPS Tripped Breaker As I Plugged Something In

Good morning, everyone. Or evening. Or afternoon. Or morrow.

Last night I was plugging something into my UPS and it popped, sparked, zapped, and tripped the breaker.

It scared the everloving shite out of me. My wife saw it from the other room.

I’m curious to know what the source was, if it’s possible trace something like that through text.

First, a monitor, small form factor PC, modem, router, and switch is connected. It’s one of these:

image

I can get the exact model when I get home, because I think mine has more plugs.

Anyway, there is some dust on it, but nothing major. I do clean it pretty regularly (monthly if not sooner). The pop/spark/trip happened without fully connecting the plug, all it did was line up and touch the adapter. I’m curious to know if that could have caused it? I noticed afterward that the adapter had exposed wiring and copper. I know, I should have paid more attention, so it goes.

After resetting the breaker and turning everything back on, there were not any issues. I plugged something else into the UPS with no issue.

Any feedback, similar experiences, or thoughts on the matter would be appreciated.

What did you plug into it? Inrush current from caps charging up can do that.

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Laptop charger that had recently been disconnected.

That big of a blast/spark/pop (not sure what to call it), though?

Arcing.

Its not a huge deal. If it keeps happening you might have an issue with the power brick.

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Noted, thanks.

My primary concern is risk of electrocution, but I’ve read conflicting testimony on that.

The consensus seems to be treat everything as hot/dangerous lol.

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Not unless you’ve got your fingers on the prongs when you go to plug it in. Hollywood has taught us that electricity will jump to anything and fuck you up but this is simply not the case.

You can touch the hot leg of an electrical circuit all you want and wont feel a thing. Its when you touch the grounding/neutral leg that there is a path for electrical flow. Think of it like a battery circuit. You have a positive and a negative, with only one of those the device wont work. You can safely touch 120V hot leg but since the ground path would be super high resistance the electricity takes another path… the one with much much much less resistance. I’ve taken 120v across my arm and in my hand, its not so bad. Wakes you up though. Its much more dangerous when you take voltage from one extremity across your body to another extremity. Think finger to toe. Thats what kills.

The exception here is lightning where the voltage is so high it will penetrate anything given the correct circumstances… including air.

Voltage is how deep you get fucked
Amperage is how much fuck there is
Wattage is the sum of fuck
Frequency is the speed of the thrust

In the case of DC, it only thrusts one direction.

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Sounds like the discharge resistor is broken (yay, lead free solder). Last time the Laptop-PSU was plugged in, the AC phase was 180° to what it was when you plugged into the UPS. The moment the gap was small enough, there was a arc discharging the capacitor.
Happens from time to time on >1 year old brick PSUs.

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