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One-Line Diagram Data Checklist

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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Project Information

Project Name

Date

Prepared By

1. Utility Service Information

Utility Company

Service Voltage

Service Type

Available Fault Current

Utility Transformer Rating

Transformer Impedance

Metering Location

Service Entrance Rating

2. Main Switchgear

Main Rating (A)

Bus Rating (A)

AIC Rating (kA)

Main Breaker Type

System Grounding

Tie Breaker

3. Downstream Panels / Transformers / Protective Devices

Tag / ID	Equip. Type	Rating (A/kVA)	Breaker Size	AIC Rating	Protective Device / Settings	Fed From	Notes

How to Use This Template

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.

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