Its cheap as hell to run a single 600 HID,especially when you get to 12/12,I grow in a commercial building I own that has a real estate business out in the front offices using 10 ton air conditioning for the grow op, 24 600 watt hps & 16 500 watt T-5's all on 12/12 on the flood & drain rooms 8 tables,in the mother/clone room I run 6 600 watt hps 24/7, 20 inline fans for cooling lights & intake/exhaust/filtration,8 rez pumps, 4 air compressors, 18 wall mount oscalating fans, 2 48 inch 2 hp box fans ,6 inline ozone generators , 8 swimming pool pumps and other misc shit for roughly 32,000 watts of draw at 12/12, down to about 7,000 watts 24 hrs a day when the flood room lights shut down, with the grow in back & business out front my power bill is about $2,200 a month & Con Ed don't bat an eye,I did the per watt math years ago & it was some silly shit like $30 per light of 12/12,its not much for 1 600 watt HID unit.
When I 1st light the room up the transformer on the utility pole out back caught fire & cooked from the surge ,I told the linemen from Con Ed I had a legal grow going & they put up a huge transformer,no problems with power for the last 8 years the grows been going