to help him out, volts x amps = watts
speaker wire is used for speakers. it could work for what you're doing. but I don't recommend it. your flexwatt is rated at so many watts per foot. add it up for your total watts. go and buy wire that has a higher rating than what you added up. so if you added up say 550 watts, that will pull 5.5 amps (watts divided by volts = amps) since you're plugging into an outlet in your home the voltage won't change but you now can figure out how to get amps or watts.
if you didn't know the volts, simple, watts divided by amps = volts.
use the right wire. is 20 dollars or even less for the proper wire worth burning your house down.