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.
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.