[jsolson]

The bus bar itself is an SPoF, but it's also just dumb copper. That doesn't mean that nothing can go wrong, but it's pretty far into the tail of the failure distribution.

The power shelf that keeps the busbar fed will have multiple rectifiers, often with at least N+1 redundancy so that you can have a rectifier fail and swap it without the rack itself failing. Similar things apply to the battery shelves.

[immibis]

It's also plausible to have multiple power supplies feeding the same bus bar in parallel (if they're designed to support this) e.g. one at each end of a row.

[eaasen]

This is how our rack works (Oxide employee). In each power shelf, there are 6 power supplies and only 5 need to be functional to run at full load. If you want even more redundancy, you can use both power shelves with independent power feeds to each so even if you lose a feed, the rack still has 5+1 redundant power supplies.