You need to know the National Electric Code. You also need a licensed electrician or you will be liable for any damages if it's not done right. If you want to save money, you can do some of the work yourself, have it verified by a licensed electrician, and then have him make the final connection at the panel.
240 volt electricity is not for average homeowners to mess with if they don't know what they're doing. 240 volt appliances usually requires a lot of power and all the connections will be critical. Be safe, do it right, and you'll sleep better at night.
240 volt electricity is not for average homeowners to mess with if they don't know what they're doing. 240 volt appliances usually requires a lot of power and all the connections will be critical. Be safe, do it right, and you'll sleep better at night.