In the early to mid-90's, a company I worked for would square foot a house. When that guy started his business, most houses only had a plug per room and a light.
These days, I don't think you can square foot, unless you go high. I think you have to line item the labor and take-off the devices, as well as knowing who's buying appliances.
Wire seems to fluctuate with the price of fuel.
Labor unit on conduit is 3.25 per hundred feet, generally, and it might be the same or a little less, even though you are drilling studs and pulling NMC.
And I would separate the estimate into undergrounds, rough-in, and trim.
And, as a wise man said, when you write your contract, get half of your money up front. You've got people to pay, even if it's only yourself.
I think others are right. Someone wants a square foot estimate just in the hopes of getting a low bidder.
