I think its from the PSU of the miner
huge chance he wired receptacle wrong.
photo the receptacle.
and post a photo of it here.
there are a lot of ways to wire it wrong.
you have three phase
so there are three hot wires and a ground going into the big box
then an outlet is attached to the big box.
the outlet needs two hots and one ground.
since the big box has three hots and a ground.
my guess is the receptacle is wired
hot-hot-hot. and that fries your psu.
i smell a small claims lawsuit as asshole owes you two pieces of gear.
taking the meter and putting it in the hot holes in the receptacle will read 208-210.
but what does the ground hole and the left hot hole show.
and what does the ground hole and the right hot hole show.
my guess is 208-210 and he gave you three hots in that receptacle.
I am tired and on a shit ipad laying in bed watching the late show.
in the morning i will find some links to show what i am describing to you.
it would be nice if asshole pays you for the gear he fried.
note i am not an electrician just a dedicated miner.
i could be wrong. so dont freak until i find some links.