We're beginning a huge project for us - building a house for my mom on our grounds, and have been told we need to upgrade our electrical box that will now service both our house and the new one, from 200 amps currently, to 400 amps. Can anyone tell me what that should cost us assuming a professional electrician provides both materials and labor? We've been given a $7000 quote, just to change out the box - how does that seem?