Thanks to this thread (FAQ: Home Tesla charging infrastructure QA) I called our electric coop yesterday, then walked out to see our transformer. The transformer for our house is currently only 10 KVA. The electric company is pretty concerned and coming out soon. Charging the Model S at 40A, 240v maxes out our transformer all by itself. Add our geothermal unit (48A continuous, 240v) and we are over double the transformer's capacity. Yikes! THANK YOU for the FAQ telling me to call! Now I guess we'll have a race between the elec co. and Tesla to see which is delivered first -- Tesla is the chicken, transformer is the egg!