Australian Electrical Drawing Symbols: AS/NZS Standards Guide

Every electrical drawing is a contract between the person who drew it and the person who builds from it — and symbols are the language that contract is written in. In Australia, that language is standardised: the same circuit breaker symbol on a Brisbane switchboard schematic must mean the same thing on a Perth mine-site single-line diagram. This guide explains which Australian standards govern electrical drawing symbols, the nine symbol categories that appear on nearly every project, and the legend discipline that keeps drawings unambiguous.

Which Australian standards govern electrical drawing symbols?

Three layers of standardisation shape a compliant Australian electrical drawing:

• AS/NZS 1102 series — graphical symbols. This is Australia’s adoption of the internationally recognised IEC 60617 symbol library, covering symbols for conductors, switchgear, protection devices, machines, measurement and more. When an Australian drawing office says “standard symbols”, this series is what they mean.
• AS/NZS 3000 (the Wiring Rules). The Wiring Rules don’t define symbols themselves, but they define the installation requirements your drawings must document — protective devices, earthing arrangements, isolation points. A symbol set is only useful if the drawing shows everything AS/NZS 3000 requires the installer and inspector to see.
• AS 1100.101 — general drafting principles. Line types, lettering, sheet layout and title blocks come from the general technical drawing standard, exactly as they do for mechanical and structural drawings. Electrical content sits inside an AS 1100-compliant sheet.

In practice, most Australian consultancies and contractors maintain a project symbol legend derived from AS/NZS 1102 / IEC 60617, then apply it consistently across the drawing set. The standard gives you the vocabulary; the legend tells the reader which dialect this particular project speaks.

The 9 symbol categories on almost every Australian electrical drawing

1. Supply and sources. Incoming mains, transformers, generators, battery banks and UPS units. On a single-line diagram these anchor the top of the sheet — everything downstream is read in relation to them.
2. Conductors and cables. Line conventions distinguish single conductors, multi-core cables, busbars and underground versus overhead runs. Cable annotations carry size, type and installation method alongside the symbol.
3. Switching and isolation. Switches, isolators, contactors and changeover devices. Getting the distinction right between a load-break switch and an off-load isolator matters — the installer and the safety inspector both read intent from the symbol.
4. Protection devices. Circuit breakers, RCDs, RCBOs and fuses, each with distinct symbols and ratings annotated beside them. This category earns the most scrutiny at inspection, because it maps directly to Wiring Rules compliance.
5. Outlets and connection points. Socket outlets, permanent connection units and data/communications points — the layer most visible on architectural electrical layouts, where symbols sit on the floor plan itself.
6. Lighting. Luminaires, emergency lighting, exit signs and switching relationships. Lighting layouts often carry switching designations (a, b, c…) that tie each fitting to its control point.
7. Motors and machines. Motors, starters and variable speed drives — the heart of industrial schematics. Symbols carry ratings, starter type and control interlocks that the switchboard builder works from.
8. Measurement and metering. Ammeters, voltmeters, energy meters and current transformers. On utility-connected work, metering symbols and their placement follow the distributor’s service rules as well as the drawing standard.
9. Earthing and bonding. Earth electrodes, main earthing conductors and equipotential bonding. Small symbols, large consequences — earthing arrangements are among the first things a compliance reviewer traces through a drawing set.

Single-line, schematic and wiring diagrams use symbols differently

The same device appears differently depending on the drawing type. A single-line diagram collapses three-phase circuits into one line per circuit and shows the power system’s architecture — supply, protection, distribution — at a glance. A schematic (circuit) diagram expands the control logic: every contact, coil and interlock drawn in its electrical sequence rather than its physical position. A wiring or connection diagram then maps that logic onto physical terminals so the electrician can terminate cables without interpreting the logic at all. Symbol discipline across all three views is what lets a project move from design intent to a wired switchboard without a phone call per circuit.

Five symbol mistakes that cause site problems

1. No legend, or a stale one. A legend copied from the last project and never edited breeds silent contradictions. Every sheet set should carry a legend showing exactly the symbols used — no more, no less.
2. Mixing symbol families. Blending IEC-style symbols with North American ANSI/IEEE symbols on one drawing forces the reader to guess. Australian work follows the IEC-aligned AS/NZS 1102 conventions — pick the family and stay in it.
3. Protection devices drawn generically. An RCD, an RCBO and a plain circuit breaker are different devices with different symbols. Drawing them all as a generic breaker hides exactly the information the Wiring Rules require the drawing to communicate.
4. Missing switching designations on lighting layouts. Fittings without control references leave the electrician to invent the switching — and the client to discover it at handover.
5. CAD block drift. Over years, office block libraries mutate — someone stretches a symbol, someone re-draws one from memory. Periodically auditing the block library against the standard keeps the vocabulary honest.

Getting compliant electrical drawings produced

ASTCAD’s electrical drafting services produce single-line diagrams, schematics, switchboard layouts and lighting/power layouts to Australian conventions — AS/NZS 1102-aligned symbols on AS 1100-compliant sheets, with legends maintained per project. Send your markups, calculations or existing drawings and we’ll return a fixed-price quote within 24 hours: request a quote.