Question Repurposing wall AC 20A dedicated circuit for my desktop?

[grandiloquentlin]

I have a wall AC that I no longer need connected to a 20A circuit outlet (the outlet receptacle says 20A - 125V). It looks like a dedicated circuit.

I want to repurpose it for either my desktop or my PC peripherals (monitors, speaker). I noticed that whenever I start my PC, the ceiling light always flickers for a brief second.

My desktop has a Cosair RM750x PSU, which takes in an input current of 10A based on the specs. My concern is that the 20A circuit's breaker would not be able to protect the PSU; if the current goes above 10A, the PSU might get fried first before the breaker flips.

Another option is to connect my PC peripherals (2 monitors and a speaker) to this 20A circuit outlet. I connect the peripherals to a power strip. I believe my power strip is not rated for 20A (because the outlet contact openings are not t-shaped).

Which is safer, or are both options bad?

 

[kanewolf]

I have a wall AC that I no longer need connected to a 20A circuit outlet (the outlet receptacle says 20A - 125V). It looks like a dedicated circuit.

I want to repurpose it for either my desktop or my PC peripherals (monitors, speaker). I noticed that whenever I start my PC, the ceiling light always flickers for a brief second.

My desktop has a Cosair RM750x PSU, which takes in an input current of 10A based on the specs. My concern is that the 20A circuit's breaker would not be able to protect the PSU; if the current goes above 10A, the PSU might get fried first before the breaker flips.

Another option is to connect my PC peripherals (2 monitors and a speaker) to this 20A circuit outlet. I connect the peripherals to a power strip. I believe my power strip is not rated for 20A (because the outlet contact openings are not t-shaped).

Which is safer, or are both options bad?

It is a little hard to see, but I believe that outlet is a standard 20A outlet which will accommodate a standard 15A plug. To determine if this is a dedicated circuit, you can look at your breaker box for a breaker that is 20A and maybe labeled for the room. I am betting that outlet was installed for a window air conditioner at some point.

 

[grandiloquentlin]

It is a little hard to see, but I believe that outlet is a standard 20A outlet which will accommodate a standard 15A plug. To determine if this is a dedicated circuit, you can look at your breaker box for a breaker that is 20A and maybe labeled for the room. I am betting that outlet was installed for a window air conditioner at some point.

That is right, it was installed for a wall AC. My breaker box did not have it labelled specifically, but I quite sure it is a dedicated circuit (because there are only a few unlabelled breakers and they are 20A breakers). Would it be safe to connect my PSU or power strip to it? Which is safer?

 

[kanewolf]

That is right, it was installed for a wall AC. My breaker box did not have it labelled specifically, but I quite sure it is a dedicated circuit (because there are only a few unlabelled breakers and they are 20A breakers). Would it be safe to connect my PSU or power strip to it? Which is safer?

A quality power strip has some surge and noise filtering. I use only IsoBar power strips.

 

[Misgar]

When I was specifying mains wiring at work for high high power radio systems in buildings, the circuit breaker rating was chosen to protect the wiring up to the wall outlet, not the equipment itself, which had its own separate protection (typically a lower rated fuse).

In any case, most 20A breakers will not trip until a continuous current approximately 2x or higher flows in the circuit, i.e. 40A for a 20A breaker. The same is true of fuses, they won't blow until double the rated current flows.

The 10A current rating you're seeing in the specs for the RM750X is the maximum continuous current the PSU will draw from a nominal 115V 60Hz AC supply, to generate the full 750W output.

During normal use, the current drawn by the RM750X will be less than 10A, because the PSU will be supplying less than 750W. The PSU will only draw what it needs from the wall, to power your computer.

The reason why your ceiling lights flicker when the PSU switches on is because the RM750X (2021 version) momentarily draws 24.930A from a 115V AC supply (or 51.640A from a 230V AC supply) at switch on. This high current spike charges the bulk capacitor in the PSU and causes a momentary volt drop in the mains, which affects your light bulbs nearby.

See review for RM750x 2021 model in link below for switch on currents.
https://www.tomshardware.com/reviews/corsair-rm750x-2021-power-supply-review/2

Where I live, the wall outlets in my house are fed from a "ring main" (not a "spur") protected by a 30A breaker. The mains voltage in my country is nominally 230VC 50Hz (not 115V 60Hz).

I would have no qualms about using a 20A feed to power my computer (after all, my wall outlet circuit breakers are rated at 30A) provided you include some additional protection for the IEC mains cord (typically rated at 10A) up to the ATX PSU. This could take the form of a fused adapter strip plugged into the wall.

In my country, mains plugs on cords that fit into wall outlets incorporate their own fuse, with ratings from 2A up to 13A. You pick a fuse in the plug to protect the cord between the wall and the equipment. Most ATX PSUs include an internal fuse, which blows when a serious overload occurs.

I would be less confident about wiring an ATX PSU or other computer equipment direct to a 20A outlet, without any additional protection, e.g. 10A fuse or additional 10A breaker.

If in doubt, consult a trained electrician. Don't mess with AC mains. It can kill the unwary.