Blog

Tutorials, templates, and references for drawing electrical single-line diagrams. Built around our free online editor at smartsld.com.

How to Read a Single-Line Diagram (Step by Step)

Follow power from source to load — voltage levels, buses, protection, and transformers — explained for beginners.

What 50, 51, 52, 87 and the rest mean on a one-line — the ANSI/IEEE device function numbers with their functions and common uses.

What each diagram type shows, when to use it, and how they relate — with side-by-side examples.

What a BESS one-line must show — battery, PCS, protection, and interconnection — plus AC- vs DC-coupled templates.

Service, panel, and EVSE circuits, with an NEC 625 load calc and a template for Level 2 and DC fast charging.

What an SLD is, the components you need, and a step-by-step walkthrough of drawing one from scratch.

Visual reference for the most common SLD symbols, with side-by-side IEC and ANSI/IEEE equivalents.

An honest comparison of the best free and low-cost alternatives to AutoCAD Electrical for drawing single-line diagrams.

What utilities require in an interconnection SLD for residential, commercial, and BESS-tied solar installations.

A worked example of a 200A residential service entrance SLD, including main panel, sub-panels, and EV / generator additions.

How large-language and vision models are being used for electrical drawings, where they help, and where they still fall short.