We observed that connecting end room picomotor driver to the power line in the same mupliple socket of OPLEV laser and PSD brings a HUGE 50 Hz in the signals.
Since picomotors are only used temporarily we have now disconneted them. We may try to connect them to another socket next time that we need them.
You could use some remote "smart" PDUs as done in virgo.
See as example
https://tds.virgo-gw.eu/?content=3&r=15139
(the name of the PDU is ENERGENIE EG-PMS2-LAN, see attached PDF file)