240 volts is for large appliances like washers, dryers, air conditioners. 120 volts (I think it might be 110 instead) is your standard voltage in regular household sockets. So if you're thinking of going 240 volts (they have a big plug at the end) it would have to plug in somewhere there is an appliance. Probably not the greatest place for a stealth grow. LOL Hope this helps.