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Comment by nine_k | Hacker News Reader

Low-power 12V or 24V DC is very doable around the house, for small-scale LED lighting, etc. But if you limit yourself to small connectors and thus reasonably low currents (like 10A, as I did), it's 120W or 240W per connector at the very top.

Serious power, in the kilowatt range, would require much higher voltage, and still much bulkier connectors and thicker conductors. OTOH 400V DC should be comparable in this regard with 220V AC, which has a 380V amplitude. The 400V DC standard is relatively widespread and well-supported by existing industrial equipment. Connectors are comparable in size to the (grounded) Euro plugs.

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Certain things get a lot more complicated when you go from AC to DC. Two of the most significant issues for home use are connects that can be disconnected under load (arcing is a serious issue here) and turning DC power on/off with mechanical switches (arcing is also the issue here).

Industrial DC devices get around these issues with stricter rules and bulkier/more complex devices. E.g. electric cars use contactors to connect batteries rather than a simpler relay/switch.

This is indeed so.

But the standard clearance for air gaps is 1 mm / kV, and arching distance is below 0.4 mm / kV. More advanced and faster mechanical switches should work fine at 400V DC.

Also IGBTs may be a preferred way, especially with various smart switches.

Sockets and plugs seem to be the hardest part to make cheap and reliable. But industrial solutions can likely be adapted.

I have no idea what the average household load looks like.

I could imagine a scenario where every outlet also has a USB port. It could run your laptop and your lights. Obviously it can't run a fridge or a stove; maybe future fridges would run off the same current as the stove?

What I'm most unclear on is the middle range. I know you can't run a hair dryer or microwave that way. What about a food processor? Maybe a toaster?

I'm trying to figure out how much that middle range makes this a deal breaker.

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