** Does anyone know what the proper wire size is for a electric range? **
To use inside of the range or to connect it to your house power supply? If to it, see the previous post.
If inside of it, it depends on which wire(s) you want to replace. Some areas may use 12, 14 or 18 gauge depending. In this case, if you take the original wire to a local appliance parts or service depot, they should be able to fashion a replacement for you out of the proper gauge as well as install terminals on it for you.