Diamond Electric Inc.(DEI) DEI is a Toronto based electrical contractor. We undertake all electrical work related to Residential, Commercial and Industial buildings. We specialize in residential electrical renovations. We carried out many rewiring KNOB & TUBE style wiring and service upgrades from 60A to 100A & 200A. DEI is very competitive in our pricing and assures you excellent value for your investment. Other key features of our company are: Guaranteed work, Fully Insured, Free Estimates, Licensed Electricians & Engineering & Design.