If my electric bill didn't go up from $85 to $200 this probably would have been my first thought but honestly it is not something I even considered and something definitely worth checking into. I am using one wall outlet for all 5 and 4 of them are on one power strip so you may be onto something here!Thats insane, there has to be something else going on. 300 watts of bulbs should be 130 to 140 degrees or something crazy. Are you using a power strip or something that could be restricting the power to the domes? If your mechanicly/electricly inclined you could use a multi-meter to check available power at you outlets.