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Comment by wmf | Hacker News Reader

Many researchers and hobbyists cannot even plug in a 10 KW 8 GPU DGX server.

Why not? It’s 40A at 240V, or 25% of the continuous load rating of a 200A 240V single-phase service.

If someone can afford an 8 GPU server, they should be able to afford some #6 wire, a 50A 2P breaker, and a 50A receptacle. It has the same exact power requirements as an L2 EV charger.

You probably run a bigger (perhaps double) neutral and care about a stronger ground. But yeah, the $12 is rounding error at this scale

In the US, you don’t need a neutral for a 240V 50A circuit on a residential single-phase service, there are two line conductors (120V to ground) both connected to a 2-pole single-phase breaker, line-to-line between the two is 240V.

You would need a neutral if it was a 208/120V three-phase service.

Neutrals and grounds are sized per the NEC, neutrals are the same size as the line conductors and equipment grounds are sized off of a table.

#6 conductors and #10 ground is what the NEC calls for.

I just haven't seen server rooms that don't demand a doubly sized neutral when one is required.

I live the NYC 208V life doing mostly resi, though.

Quick search of the spec for that is 6 power supplies, 2 of which are redundant. Looks to use a neutral to me. Says it uses C19/C20 connectors

edit: wait most ranges use 14-50R outlets and need a neutral ran. I am calling your statement into question. Surely harmonics and 120V internal draws cause non-zero neutral current. And I'm sure GPUs have harmonics being semiconductor flavored.

Turns out you are correct on both points!

My bad, NEMA 14-50R is a 4-wire receptacle with a neutral.

I learned something new today, 200% neutrals are not required by the NEC but can help with non-linear loads, and certain transformers that mitigate harmonics need 200% neutrals.

I'm thinking you'd have a hard time fitting it in a smaller residential unit purely because of the load calculations. You'd probably have to add 3000W worth of AC units or heat pumps. Considering it's 4+ space heaters worth of output, I think you could fit it on a 200A service. 150A if you're bold and use optional calcs (these assuming you have electric cooking). To your point, basically the same as if you have an EV but with some cooling in there.

That doesn't exactly bode well for the EV revolution, then, does it?

wut?

The average commute in the United States is about 24 miles a day round trip. That's about 10 kWH. That's enough to charge overnight on a 15A circuit.

You can drive around with 24 miles of charge, but ... I'll pass, thanks.

In reality, if you have a dryer outlet, you have a good fraction of 10 kW available.

I just put in a dedicated 50 amp circuit myself and my car charges from ~25% to full in about 6-7 hours. But I wanted to present the lazy worst case scenario. The warrior's FUD here is that there isn't enough easily available lithium for everyone in just California alone to have one.

Almost all home EV charging is <=10kW.

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