If you dont know about electricity dont fool with it cause 240 volts is no punk. Are your lights 240 volts? Why are you using 240? It would be simpler to run (2) breakers of 20 amps (or more depending on your gauge of wire) each at 120v. One circuit will run the lights and the other for your other stuff. If you have something that needs 240v you will need to tie two legs of 120v power together to achieve the 240v. Im gonna take a stab at what you want to do here so correct me if im wrong. You want 240v but want to tap off it for 120v? Is this correct?If so I wouldnt advise it, it gets tricky if you dont know what your doing. Find a buddy who is an electrician if possible. Be careful and good luck.