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In my office, I have 3 PCs.

I have measured (killawatt device at wall) that they draw 35W at idle, and max 200W at full blast.

So I expect them to stay below 600W at all times. (NOTE: the PCs all have 80-Gold 550W PSUs, but they never draw 550W, they are only capable of drawing 200W under load, verified with killawatt device.)

Yet, my circuit breaker has tripped twice in two days.

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My home is 120V, so 600W draw, would be 5 Amp, well below the 15 Amp?

Note: the lights of my office are on a separate breaker.

Do circuit breakers wear out over time? Does it need replacement?

UPDATE

This is an 8 year old house in BC, Canada. I use one of the bedrooms as my office, with 3 PCs.

For one of the computer screens, when unplugged, I measured roughly 1MΩ between ground pin and other pins, at the plug. Is that normal? It is an Acer X34 monitor with powerbrick.

UPDATE 2

When tripped, the computers were running normally, none of them were being switched on or off. It seemed to be very random events.

All three computers are on separate wall outlets. No UPS, no batteries.

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    Has this been working for a while with all the computers and now you're having issues? These are combo GFCI/AFCI breakers, so they are most likely tripping from arc detection or a ground fault rather than excessive load. Edit: Maybe this is just an arc fault breaker, not super familiar with GE breakers.
    – JPhi1618
    Dec 10, 2021 at 21:45
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    Sorry for the scummy repair manual site, but these instructions will tell you a bit more about it. It is a AFCI only breaker. It says "COMBO" because it protects against Parallel Arc faults and Series Arc faults (PER and SER on the test switch).
    – JPhi1618
    Dec 10, 2021 at 21:57
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    Is this a new house or new addition that requires an AFCI breaker? If not, you might want to just replace it with a standard 15A breaker.
    – JACK
    Dec 10, 2021 at 22:04
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    To investigate which computer is tripping the breaker, plug in one computer into a different circuit with an extension cord. Dec 10, 2021 at 22:14
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    @Bram In that case (and given the info about them being AFCI breakers), I would guess it is the breakers being overly sensitive.
    – TylerH
    Dec 10, 2021 at 22:20

2 Answers 2

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A room designated on approved plans as a "bedroom" required an AFCI breaker 8 years ago. It still does.

Check the PC power supplies that they have a CSA or UL/c or ETL/c certification. Unfortunately there is a lot of cheap crud coming in from overseas via mail order. If they do not, they must be replaced with listed units. The devices inside the PC and their use decide its power consumption.

The problem is likely an arc fault or a ground fault trip (AFCIs do both, though the ground fault detection is not up to GFCI standards). That could point to a faulty power supply, or possibly an older and unduly sensitive AFCI.

However, GE has improved their AFCIs considerably, and the latest don't even use the neutral wire, which means, they are not even doing ground fault detection. I'm not a fan of that, though... if there's a ground fault, I'd rather the A/GFCI find it, than your child.

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Since the breaker does not trip when the PCs are switched on, the reason has most likely nothing to do with high power surges. Short time current spikes of 2 or 3 times the rated 15A, which may occur during the initial loading of the empty capacitors in the power supplies won't trip the breaker.

But a kind of mini arcing can often occur in the (often) black cable inlets/plugs of monitors or PCs if the power cable plugs are not inserted deep enough against the raising mechanical resistance and/or the contacts are worn off and/or if the power cables are moved/touched.

An arcing can be sometimes heard if the plug is inserted in the PC/monitor.

So a check of all (six ?) power plugs could help. If not, the breaker should be exchanged in the hope that newer ones are better avoiding those nuisance trippings. plug

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    Note: modern PCs don't "switch off" - the power supply is always connected to the mains, but goes into a very low power mode when the PC is shut down or hibernated. A power supply fault can trip the breaker even when the PC is apparently switched off.
    – grahamj42
    Dec 11, 2021 at 7:18
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    @grahamj42 Yes, many electronic items do use (soft) switches on the low voltage side - which saves production costs. But for 2 reasons hard switches (f.e. in extension plugs) are recommended for those devices: 1. Standby-losses are avoided and 2. possible fire hazards are much less likely.
    – xeeka
    Dec 11, 2021 at 13:41

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