If by "exploding" power supply you mean the potential for a power supply to explode with eruptive force and destroy other equipment in the rack, I believe that the other equipment being destroyed would be considered an multiple failure. It's very unlikely that a power supply could do that (although I guess anything is possible). A proper datacenter built with Datacenter-grade equipment will have multiple redundant power supplies in a blade enclosure, fed by different rails, which come off of different main lines in to the building. So a single failed source of power won't cause a failure.