I took 2 S15's home (to run for heat) on my 240 outlets and the PSU's on both units failed within 24 hours. Both PSU's got quite hot. I think my 240 outlets actual voltage may vary a little higher than that, maybe 242 or 243. They may have simply tripped a safety shutdown due to either voltage or temperature, but regardless, both ceased to function (no power) there was no way to reset them. Both units went to Bitmain and were replaced under warranty. I will not attempt to run anymore of these at or near 240v even though the spec says 200-240v. They seem to be happiest somewhere in between those numbers. I've had some units running nearly a month on our 208v rack with zero issues.