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AI drafting for one-line diagrams

AI One-Line Diagram Drafting

The one-line is the sheet every other electrical drawing has to agree with, and it is usually redrawn from an engineer's red pen on last week's print. Nomic drafts the one-line or riser diagram in CAD from that markup or an equipment list, keeps every panel and feeder name consistent with the schedules, and labels the available fault current from your engineer's study.

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Last reviewed: November 2026

You send

  • The engineer's markup, sketch, or equipment list
  • Short-circuit and coordination study report
  • Panel schedules and the feeder schedule
  • Utility service data and transformer nameplates
  • Your one-line symbols and CAD standards

Nomic hands back

  • One-line and riser diagrams as DWG files
  • Fault current labels with calculation dates
  • A mismatch list against panel and feeder schedules
  • Clouded PDFs and open questions for the engineer of record
UTILITY 12.47 KVT-1 2000 KVA4000A MAINMSB 480Y/277V 3PH 4W4#500 KCMILHP-1480Y/277V4#500 KCMILLP-2A75 KVA4#500 KCMILMCC-1MECH4#500 KCMILATS-1LIFE SAFETY4#500 KCMILEV-1EV CHARGINGGGEN-1 500 KW1ASINGLE-LINE DIAGRAMSCALE: NONE1234CONSULTING ENGINEERSREVISIONS1ISSUED FOR REVIEWPROJECTCEDAR LOFTSSCALENONEDATE11/26/2026KEY PLANSHEET TITLESINGLE-LINEDIAGRAMSHEET NUMBERE-601

On the sheet

Single-Line Diagram, annotated

A single-line diagram from the utility transformer through the switchboard to each feeder and the generator.

  1. 1Utility service transformer
  2. 2Main switchboard bus
  3. 3Feeder breaker and conductors
  4. 4Generator and automatic transfer switch

The problem

The one-line is redrawn from markups, and the names drift

Most one-lines start as a hand sketch or a marked-up print from the engineer: a new 75 kVA transformer here, a feeder upsized there, two panels renamed after the architect split a floor. The drafter redraws each symbol, writes the breaker frame and trip, the conductor and conduit size on every feeder, the transformer kVA and impedance, and the panel voltage and bus rating, then does it again when the next markup arrives.

Because the one-line feeds the panel schedules, the feeder schedule, and the riser, small slips spread. A panel called DP-2 on the one-line shows up as DP2 on the schedule, a feeder tag disagrees with the feeder schedule, a transformer secondary has no overcurrent device shown, or the fault current labels still carry numbers from before the utility changed the service transformer. Large services add the rules reviewers look for every time, including ground-fault protection on big 480Y/277V mains and arc energy reduction on breakers rated 1200A and up.

01 / Draft

Drawn from the engineer's markup

Attach the marked-up print, the equipment list, or a sketch, and name the sheet. Nomic draws the distribution from the service down to each panel with your one-line symbols, writes the feeder, breaker, and transformer data on it, and splits emergency and standby branches the way the markup shows.

  • Service, switchboards, transformers, and panels from the markup
  • Feeder tags matched to the feeder schedule
  • Riser diagrams for multistory buildings and meter stacks
02 / Labels

Fault current labeled from the engineer's study

Your engineer runs the short-circuit and coordination study. Nomic reads the study report and writes the available fault current and the date of the calculation at each piece of equipment, as NEC 110.24 and 408.6 require, and flags any equipment the study does not cover.

  • Available fault current and calculation date at each bus
  • Equipment ratings compared with the study values
  • Equipment missing from the study listed for the engineer
03 / Check

Checked against the code and the schedules

Nomic checks its own one-line against the NEC edition you name and against every panel schedule and the feeder schedule in the set. Each change is clouded, and the questions that belong to the engineer, such as selective coordination, are listed instead of answered.

  • Ground-fault protection and arc energy reduction on large mains
  • Transformer overcurrent protection on both sides
  • Panel and feeder names compared with the schedules

Checked against

The code and documents behind every sheet

Name the editions the project is designed to and Nomic checks its own drawing against them before handing it back. Your engineer or architect of record makes the final call and stamps the set.

  • NEC 110.24 and 408.6 available fault current marking
  • NEC 408.4(B) source of supply identification
  • NEC 230.95 and 240.87 for large services
  • NEC 450.3 transformer overcurrent protection
  • NEC Articles 700, 701, and 702
  • The engineer's short-circuit and coordination study

How it works

From a sentence to a stamped set

  1. Step 1

    Ask for the drawing

    Say what the sheet needs to show and attach the backgrounds, markups, cutsheets, or photos. A sentence is enough to start.

  2. Step 2

    Nomic drafts it in CAD

    Nomic works in CAD on its own computer, on your layers and blocks, following how your firm drew the same thing before. It saves real DWG files to the project.

  3. Step 3

    Nomic checks its own work

    The drawing is checked against the code editions you name and the source documents. Everything Nomic drew is clouded, and open questions are listed.

  4. Step 4

    Your team reviews and stamps

    Your engineers and architects review the clouded changes, make the final call, and issue the set under their own stamp.

FAQ

Frequently asked questions

Yes. Nomic works in CAD on its own computer and drafts the one-line from the engineer's markup, a sketch, or an equipment list. It saves a DWG with your symbols, feeder tags, breaker and transformer data, and checks it against the code and the schedules before your engineer reviews.

No. The short-circuit, coordination, and arc flash studies stay with your engineer and their study software. Nomic reads the study report, labels the available fault current on the one-line, compares equipment ratings with it, and flags equipment the study does not cover.

A one-line shows the electrical distribution as a single line from the service to each panel, with ratings and feeders. A riser diagram shows the same equipment arranged by floor, which is common for multistory buildings and multifamily meter stacks. Nomic drafts both and keeps the names the same on each.

Nomic compares every panel name, voltage, bus rating, main breaker, and feeder on the one-line with the panel and feeder schedules and lists each mismatch. When the engineer renames or resizes something on the markup, Nomic updates the one-line and clouds the change.

No. Nomic saves DWG files to the project that open in AutoCAD or any DWG editor. It does not edit Revit models, so Revit teams link the DWG or update the model from the change list Nomic writes.

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AI One-Line Diagram Drafting: Single-Line and Risers | Nomic