Your only pulling about 150 watts from your lights,this should tell you that other electtrical devices are plugged in & in operation on the same circut as your lights,several rooms can be ran from a single circuit,you need to lighten the load on the circuit in question,right after you throw away that multi tap extension cord you have (white or brown dollar store cheapy right ? ) & replace it with a heavy duty grounded extension cord,then hook up a heavy duty 3 way grounded outlet to the heavy duty extension cord to get power to the lights.
Im not trying to be a dick but i have a feling that this grow is a "stealth grow",if so be aware that others saftey depends on you researching electricity & then applying what you've learned in a manner that wont create a fire hazzard that will kill people,so far the grow you describe sounds very unsafe if the power supply cant put out 150 watts without blowing a breaker,plus the fact you cant figure out why the extension cord & 150 watts of light blow the breaker,so far your understanding of electricity is at the point what your doing is very unsafe to you & others in the home.
Be safe & think adult here,research how homes are wired & play it safe.