An electrical single line diagram (SLD) is a drawing that shows the electrical connections and components of a power distribution system in a simplified form. The purpose of an SLD is to provide a clear and concise overview of the electrical system, including the relationships between the various components and the flow of power throughout the system. A single-line diagram helps you to know where you need to perform troubleshooting. It also simplifies the troubleshooting process because you’ll have current information to work from.
Single-line diagrams are important for preventing electrical accidents. Your facility is safer for employees when your electrical single-line diagram is kept up to date by reflecting the current power system setup.To comply with local state and  regulations and standards, a single-line diagram is often needed. A system is far more dependable when it is well-documented. An accurate diagram ensures optimum system performance and coordination for all future testing. A single-line diagram is essential when preparing a critical response plan. It can become a facility’s lifeline of information when updating or responding to an emergency.