running other peoples miners in my house??

[stephen.cobb]

I hope this is the right section for this. dont know..

so my friend bought 2 antminer s9's and a prebuilt 8 gpu ether rig. and he ran them 1 day in his apartment while he was at work. he came home to a oven and neighbors complaining of the noise. lol... that afternoon he asked me how much I would charge to run his equipment.
he just wants to sit back and collect the money.. LOL
I have the cooling capacity and the power his equipment needs available in my main panel. but what and how do I charge???
I have to run 4 more 20 amp circuits because his gpu miner has 2 psu's.
electric cost + 50% or something like that?
thanks all