Pre-Diagram Data Capture Worksheet · Fillable · Autosaves Locally
This is not a diagram-drawing tool. Producing an actual one-line diagram requires CAD/electrical design software. What this worksheet does is capture, in one organized place, the raw system data an engineer needs before and while building that diagram — utility service characteristics, main switchgear rating, and every downstream panel/transformer with its breaker size and protective device settings. Fill this out first, then hand it to whoever is drafting the one-line (including yourself) as a single source of truth for the numbers that belong on the drawing.
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Complete Section 1 (Utility Service Information) first — this data typically comes from the utility company's service specification or a recent utility letter, and it anchors the top of every one-line diagram.
Complete Section 2 (Main Switchgear) using the equipment nameplate or the switchgear submittal — main/bus ratings and AIC rating are required to verify the equipment can withstand the available fault current from Section 1.
Use Section 3 to list every downstream panel, transformer, MCC, or major branch circuit device feeding from the main switchgear — one row each, including the protective device type and its trip settings if already known.
Hand the completed worksheet to whoever is drafting the one-line diagram (CAD/electrical design software) — every value on this sheet is a data point that belongs directly on the drawing.
Click Print / Save as PDF to keep a record of the data used, useful for coordination studies, arc-flash studies, or as backup documentation attached to the final one-line diagram.