This AutoCAD DWG file includes a complete Single Line Diagram (SLD) of a Distribution Board, showing circuit breakers, wiring connections, and load distribution for lighting, power, and mechanical systems. CAD Blocks for Electrical Projects Free Download! CAD Blocks & BIM Objects for Electrical Projects in DWG, RVT, RFA, SKP and more. A distribution box is the heart of any electrical system. It takes the incoming power and safely distributes it to different circuits throughout your building. Whether you're an electrician or a DIY enthusiast, this guide will help you understand the basics of home electrical distribution.