# Three-phase socket outlet Canonical URL: https://eloragrid.ai/symbols/iec-three-phase-socket-outlet Publisher: Elora Grid Updated: 2026-10-28 Lookup label: SO3 Drawing use: GA Reference families: IEC ## Symbol convention Convention: IEC Form: Three-phase socket outlet IEC 60617 installation-plan style (architectural and topographical installation symbols); independently drawn, not certified IEC geometry or a database identifier. Installation plan mark for a polyphase socket outlet, shown with three conductor strokes on the outlet lead. ## In plain English ### What does Three-phase socket outlet mean? A three-phase socket outlet supplies portable or semi-fixed three-phase equipment such as compressors, welders, kilns and site distribution boards. Plan symbols typically show the outlet form with three short oblique strokes, the same convention used on single-line diagrams to indicate three conductors. ### A simple example Because three-phase outlets differ in pin arrangement (with or without neutral), current rating and phase rotation, the symbol is nearly always accompanied by text such as 20 A 5P or 32 A 4P. The electrician needs this to choose the accessory and to confirm phase rotation at commissioning. ### What the drawings help you do The strokes indicate phase conductors only. They do not show whether neutral and protective earth are included, and they do not replace the circuit schedule entry for cable size and protective device. ### This particular reference Installation plan mark for a polyphase socket outlet, shown with three conductor strokes on the outlet lead. A single-phase earthed outlet has no conductor strokes; the three strokes mark the polyphase supply. ### Terms - Phase: One of the related AC waveforms in a power system. - Rating: A value stating the conditions for which equipment is specified. - Schematic: A drawing showing function and connections rather than physical appearance. Concept diagram: Identify the device and form → Read the connections and state → Check the equipment reference A guide to reading this reference. The original symbol illustration and its drawing notes appear below; these boxes are not a wiring diagram. - [IEC graphical symbols for diagrams](https://tc3.iec.ch/tc-activity/graphical-symbols-for-diagrams/) - [Autodesk IEC-60617 preview: Single and duplex power-receptacle forms](https://help.autodesk.com/cloudhelp/2021/ENU/AutoCAD-Electrical/files/GUID-7DAEDB03-74FC-47A2-9C50-9164297AA5A3.htm) - [Electrical installation design methodology and references](https://www.electrical-installation.org/enwiki/General_rules_of_electrical_installation_design) ## What it represents A three-phase socket outlet supplies portable or semi-fixed three-phase equipment such as compressors, welders, kilns and site distribution boards. Plan symbols typically show the outlet form with three short oblique strokes, the same convention used on single-line diagrams to indicate three conductors. Because three-phase outlets differ in pin arrangement (with or without neutral), current rating and phase rotation, the symbol is nearly always accompanied by text such as 20 A 5P or 32 A 4P. The electrician needs this to choose the accessory and to confirm phase rotation at commissioning. The strokes indicate phase conductors only. They do not show whether neutral and protective earth are included, and they do not replace the circuit schedule entry for cable size and protective device. ## How to read it - Count the strokes and read the pole annotation; a 4-pin and a 5-pin outlet look the same without the label. - Check whether an isolator or interlocked switch is shown in the same position. ## Information to show or reference - Write current rating and pin count beside the symbol. - State whether a neutral is required. - Record phase rotation verification in the commissioning checklist. ## Important distinction A single-phase earthed outlet has no conductor strokes; the three strokes mark the polyphase supply. ## Facts - Conductor indication: Three oblique strokes for the phase conductors - Typical rating text: Current, pin count and voltage - Exact standard graphic: Not reproduced here; confirm the form against IEC 60617 and the project legend ## Public references - [IEC graphical symbols for diagrams](https://tc3.iec.ch/tc-activity/graphical-symbols-for-diagrams/) — IEC. IEC committee context for graphical symbols used in diagrams and installation documents; not a source of reproduced artwork. - [Autodesk IEC-60617 preview: Single and duplex power-receptacle forms](https://help.autodesk.com/cloudhelp/2021/ENU/AutoCAD-Electrical/files/GUID-7DAEDB03-74FC-47A2-9C50-9164297AA5A3.htm) — Autodesk. Public receptacle family in an IEC-oriented CAD library, useful for comparing schematic receptacle forms with plan marks. - [Electrical installation design methodology and references](https://www.electrical-installation.org/enwiki/General_rules_of_electrical_installation_design) — Schneider Electric — Electrical Installation Guide. Installation design methodology context: circuits, outlets and final distribution are planned before symbols are placed. ## Graphic scope Independent original educational concept illustration by Elora Grid. Not a certified standards graphic or manufacturer footprint. Unitless; not to scale. Original artwork licence: https://creativecommons.org/licenses/by/4.0/. Publisher material is linked only.