Incident: Thomson B788 over Atlantic on Jul 12th 2013, lavatory woes
"Passengers reported that all but 2 lavatories malfunctioned
obviously as result of an electrical problem. "
HOWEVER.
Having been one of the teams installing PGE harnesses in tranche one and two A380's I say do not to underestimate the power consumption of these services, even on a "smaller" aircraft.....