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by cogman10 15 hours ago
Ok, how are people powering these things? 2.4kW is well beyond a standard circuit in the US. Are people having 240V/30A circuits installed? Are they hijacking the dryer plugs? EV charger plugs? Hottub circuits?
5 comments

When I dipped my toes into vaguely-serious eth mining with GPUs 5 or 6 years ago, I just installed a dedicated 240v, 30a circuit in the basement. The run of cabling was short, the basement was unfinished utility space, and the parts didn't cost very much. It went together quickly.

The business of protecting individual power cords was handled by an Eaton PDU that had a 30a twist-lock plug on one side and a couple of rows of current-limited IEC C13 sockets on the other side.

240V-20A circuits will handle 3.8kW continuous. It’s probably a 240V-20A circuit, as that is what the power supplies typically want. Also, easy to convert an outlet to 240V, if the breaker is dedicated to that outlet. Just requires swapping the breaker and the outlet, not the wires.
I don't think that's exactly common other than for outlets that are already wired for those specialized purposes, no?

Certainly on my panel the only "single outlet" breakers are hot water, AC, oven/stove, dryer.

I agree it’s not common. Doesn’t mean you couldn’t do that. If every room has its own breaker for the outlets in that room, you could convert that room to 240V, as an example, though.

Also, another place where you might already have this outlet: some older houses that use window AC units that were larger had 240V 20A outlets. Not common these days, but you can still buy these types of window AC units.

Chaining two PSUs on separate circuits is also an option. If they're using the MaxQ versions though, the total GPU power draw is only ~1200W. The bigger question to me is how are they cooling it? Sticking an AC in that room just doubles the power draw issues.
If I wanted to use two circuits without running extension cords, every place I've lived would mean getting electrical rewired.

If you're gonna get rewired you may as well install a 240v circuit, and some 120v 20a sockets while you're at it.

Fair point.

I'm very close to just running a cord over or devising a way to put my machine closer to a second circuit because my rental is horribly setup and both my bedroom AC and living room desktop (that also doubles as a ML training box) end up on the same circuit.

You can break the tabs on a 15A or 20A duplex receptacle to have (2) single 15A or 20A dedicated circuits on a single duplex receptacle.

It would require an additional run of 14/2G romex (12/2G for 20A) and a single-pole breaker, but allows you to skip cutting in an old work box to add a 2nd duplex receptacle.

You could possibly replace the existing 14/2G with 14/4G which has enough conductors for both circuits.

If you are going to do that, why not install a NEMA 5-20R receptacle, that has two independent circuits and is backwards compatible, as well as being rated for 20A per plug?

The receptacle is the easy part, running the new circuit is the hard part.

Or you know, install a new 240V receptacle.

If I have to:

1) Run wire

2) Get a bigger breaker box

3) To do it legally, hire an electrician and maybe get a permit

Replacing the receptacle is like, <1% of what's involved there.

Breaking the tabs on the existing receptacle prevents one from having to use a jab saw or multitool to cut a hole in the gypsum wallboard or plaster and install a cut-in/old work box to add a 2’d duplex receptacle: https://www.homedepot.com/c/ah/how-to-install-remodeling-box...

Any 15A or 20A duplex receptacle can have the tabs broken to get two separate 15A or 20A simplex receptacles, you don’t need a 5-20R for that, a 3-wire 5-15R works just fine.

Someone upthread mentioned 1.2kW load which a 15A receptacle handles just fine: .8*120*15=1,440W continuous. Bumping that up to 20A only gets you an additional 480W of continuous load: .8*120*20=1,920W. A continuous load is one that runs for 2 hours or longer, the overcurrent protection and wire must be upsized by 1.25x (or derated to 80%)

Most receptacles in homes are wired with 14/2 romex which is only good to 15A (in homes, which use the 60C ampacity column) which is why I suggested pulling another run of 14/2G romex and breaking the tabs. Pulling 14/2 romex to an existing receptacle usually isn’t that hard if you have a fish tape.

AFAIK computer PSUs can’t easily use 240V power without a PDU in the middle, but I’m likely wrong on that, especially for server PSUs.

Almost all computer PSUs I have ever seen are 110/220 since they don't make different models for Europe.
It is basically on 2 different circuits/breakers. Asus wrx90e supports 2 psu as well. You may need to synchronize both psu and several adapter for this is available in Amazon. Soon planning to upgrade it to 240V
exactly, I had a 220v 30a circuit installed to run a multi-GPU server in my basement.

I'm air cooling so I set -pl 450 so I'm not running them all at the full 600w