i ran 5 1k hps 12/12 and 1 1000watt mh 24/7 in a 2 bedroom home for over a year Plus had heat on in the winter months have a 400+ power bill eah month. I have also seen a few commmercial grows in BC canada use 20+ lights (1000 watts each) in a 5+ bedroom home and have no worries with a 600-800 power bill