Based on the 1999 National Electrical Codeâ, this invaluable guide begins with such basics as electrical fundamentals, formulas, and circuits. More advanced topics such as conductor sizing and protection, outlet and junction boxes, motors, voltage drop, residential and commercial load calculations, and delta-wye transformers follow additional chapters on alternating current circuits, transformers, and generators. This free app is a construction calculator with integrated reference materials and access to hundreds of additional calculations as add-ons.