How to calculate size of wire for house wiring? All Questions › Category: Electrical Estimating And Costing › How to calculate size of wire for house wiring? 0 Vote Up Vote Down Chetan Shidling asked 5 years ago I need short information. 1 Answers 0 Vote Up Vote Down Chetan Shidling answered 5 years ago To calculate size of wire you need to calculate total load of house, then calculate load current and observe the wire table and select the size of wire by seeing load current. You can search on Google as wire table for house wiring you will find.