Electrical drafting is the production of technical drawings that document electrical systems — from simple single-line diagrams to complex panel layouts, schematic diagrams, wiring diagrams, and cable schedules. In Australia, electrical drawings must comply with AS/NZS 3000 (Wiring Rules) and applicable standards for the industry sector (AS/NZS 61439 for switchboards, AS 61511 for process safety systems, etc.).
Types of Electrical Drawings
| Drawing Type | What It Shows | Used By |
|---|---|---|
| Single-line diagram (SLD) | Simplified overview of the electrical system — main switchboard, sub-boards, circuits, protection devices | Electricians, engineers, certifiers |
| Schematic diagram | Detailed circuit operation — showing all connections between components using standard symbols | Panel builders, commissioning engineers |
| Wiring diagram | Physical layout of wiring — showing actual wire runs, terminal numbers, cable IDs | Electrical contractors, maintenance |
| Panel layout drawing | Physical arrangement of components inside a switchboard or control panel | Panel builders, fabricators |
| Cable schedule | Tabular list of all cables — from/to, cable type, core count, length, conduit route | Installers, project managers |
| Loop diagram / instrument loop diagram | Shows the connection of field instruments to control system I/O | Instrumentation engineers, PLC programmers |
| Site layout / electrical services plan | Floor plan showing power outlet, lighting, cable tray, and conduit routing locations | Electrical contractors, builders |
| Protection relay settings sheet | Tabulated protection settings for each relay in the system | Protection engineers, network operators |
Australian Standards for Electrical Drawings
- AS/NZS 3000 — Wiring Rules: the foundational standard for all electrical installations in Australia. Electrical drawings for AS 3000 compliance show circuit protection, earthing, and switchboard layouts.
- AS/NZS 1102 — Graphical symbols for electrical diagrams: defines the standard symbols used on Australian electrical drawings (switches, breakers, relays, motors, transformers).
- AS 61439 — Switchgear and control gear assemblies: panel layout drawings and test documentation for switchboards must comply.
- AS 60617 — Graphical symbols for diagrams: IEC-based symbols for schematic and wiring diagrams.
- IEC 81346 — Reference designation system: structured naming and numbering of electrical components across drawings.
Electrical Drafting Software
| Software | Best For | Industry Use in AU |
|---|---|---|
| AutoCAD Electrical | Full electrical schematics, panel layouts, wire numbering, BOM generation | Very High — manufacturing, mining, industrial |
| Eplan Electric P8 | Large-scale panel and MCC design, IEC standards-compliant | High — process industries, OEM panel builders |
| SEE Electrical | Mid-range schematic and panel design | Medium — building services, smaller panels |
| Revit MEP | Building electrical systems in BIM — power, lighting, data | High — commercial construction |
| AutoCAD (standard) | Site plans, 2D electrical layouts | High — general electrical contracting |
| CADElec / ProfiCAD | Basic schematic drafting | Low — small workshops |
What Electrical Drawings Must Include (AS/NZS 3000)
Under AS/NZS 3000, electrical installations of a certain complexity must have drawings prepared before work begins. A compliant set of electrical drawings typically includes:
- Single-line diagram showing incoming supply, main switchboard, all sub-boards, and circuit protection devices with ratings
- Earthing and bonding diagram showing earth conductors, main earth bar, and protective earth connections
- Circuit schedule listing every circuit: circuit number, description, cable size, protection device type and rating
- Panel layout drawing for each switchboard showing component positions and cable entry points
- For industrial installations: schematic diagrams for all control circuits, motor starters, and safety systems
Reading Electrical Drawings: Key Symbols and Conventions
| Symbol / notation | Meaning |
|---|---|
| — (horizontal line, single) | Single-line representation of a three-phase circuit |
| MCB / MCCB | Miniature / moulded case circuit breaker — with rating (e.g. 32A) |
| RCD / RCCB | Residual current device — with sensitivity rating (e.g. 30mA) |
| RCBO | Combined RCD + MCB |
| → (motor symbol) | Motor — with horsepower or kW rating and voltage |
| K1, K2 | Contactors — relay-operated switches for motor starters |
| E-Stop | Emergency stop — normally-closed pushbutton |
| PE / GND | Protective earth / ground connection |
| N | Neutral conductor |
| L1, L2, L3 | Three-phase line conductors |
| Cable callout: 4C+E 2.5mm² Cu | 4-core + earth, 2.5mm² copper conductor cable |
ASTCAD Electrical Drafting Services
ASTCAD’s electrical drafting team produces compliant electrical drawings for industrial, commercial, and infrastructure projects across Australia using AutoCAD Electrical, Eplan, and Revit MEP. Services include:
- Single-line diagrams and schematic drawings
- Panel layout and switchboard drawings
- Wiring diagrams and cable schedules
- Instrument loop diagrams
- Site plans and electrical services plans
- AS/NZS 3000 compliance documentation sets
- Conversion of handwritten or legacy drawings to AutoCAD Electrical
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