[quickthrowman]

> The power people talk about arc flash protection and worker safety.

800VDC is insanely scary stuff.

> At present, no consensus standard provides a validated methodology for calculating direct current (dc) arc-flash incident energy.

This means that establishing proper PPE for DC arc flashes is not possible right now. If I was asked to provide electricians to work on these racks, I would only allow my electricians to approach them, let alone do any work, if they were de-energized, full stop. Even inspecting anything while they’re energized (without doing any work) would be insane, in my opinion. Nobody’s life is worth losing over a rack of servers, and the incident energy for a 480V AC circuit that can power a 1 MW rack (1503 amps) can exceed 40 cal per cm^2 depending on the electrical system already, and there is no PPE that protects you above that incident energy level.

[Animats]

Subway and trolley traction power is at those levels. SF Muni overhead is 600VDC. BART is 1000VDC. Caltrain is 25,000VAC, because it was wired for high speed rail.

[eichin]

800VDC at (merely) hundreds of amps is a high-end electric car charger. (Those are a lot easier to shut down individually, though.)