# Socket outlet with interlocked switch Canonical URL: https://eloragrid.ai/symbols/iec-socket-outlet-with-interlocked-switch Publisher: Elora Grid Updated: 2026-10-28 Lookup label: SOI Drawing use: GA Reference families: IEC ## Symbol convention Convention: IEC Form: Socket outlet with interlocked switch IEC 60617 installation-plan style (architectural and topographical installation symbols); independently drawn, not certified IEC geometry or a database identifier. Plan mark for an outlet whose switch is mechanically interlocked so a plug cannot be inserted or withdrawn while live. ## In plain English ### What does Socket outlet with interlocked switch mean? Interlocked socket outlets are used for industrial plugs, welding outlets, portable plant supplies and higher-current three-phase outlets. The interlock forces the user to switch off before the plug can be removed or inserted, which prevents drawing an arc at the pins. The plan mark adds a switch stroke and a small interlock bar to the outlet form. ### A simple example On industrial layouts the symbol is often paired with a current rating and pole count written beside it, for example 32 A 5-pin. The estimator should expect a heavier enclosure, sometimes with an integral fuse or circuit breaker, and the installer should expect a surface-mounted accessory rather than a flush plate. ### What the drawings help you do The interlock mark does not confirm the presence of overcurrent or residual-current protection inside the unit. Check the schedule for combination units that include a breaker or RCD. ### This particular reference Plan mark for an outlet whose switch is mechanically interlocked so a plug cannot be inserted or withdrawn while live. A simple switched outlet allows the plug to be withdrawn while supplied with operating power; the interlocked form mechanically prevents it. ### 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/) - [Elementary switching devices](https://www.electrical-installation.org/enwiki/Elementary_switching_devices) - [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) ## What it represents Interlocked socket outlets are used for industrial plugs, welding outlets, portable plant supplies and higher-current three-phase outlets. The interlock forces the user to switch off before the plug can be removed or inserted, which prevents drawing an arc at the pins. The plan mark adds a switch stroke and a small interlock bar to the outlet form. On industrial layouts the symbol is often paired with a current rating and pole count written beside it, for example 32 A 5-pin. The estimator should expect a heavier enclosure, sometimes with an integral fuse or circuit breaker, and the installer should expect a surface-mounted accessory rather than a flush plate. The interlock mark does not confirm the presence of overcurrent or residual-current protection inside the unit. Check the schedule for combination units that include a breaker or RCD. ## How to read it - Check the rating text: interlocked outlets are usually specified by current, poles and IP rating together. - Do not confuse the interlock bar with the protective earth bar on a domestic outlet. ## Information to show or reference - State current rating, pole count and plug standard. - State whether overcurrent or residual-current protection is integral. - Note IP rating and mounting surface. ## Important distinction A simple switched outlet allows the plug to be withdrawn while energised; the interlocked form mechanically prevents it. ## Facts - Typical location: Workshops, plant rooms and outdoor plant supply points - Added information: Plug cannot move while the switch is on - 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. - [Elementary switching devices](https://www.electrical-installation.org/enwiki/Elementary_switching_devices) — Schneider Electric — Electrical Installation Guide. Explains elementary switching functions such as isolation, control and functional switching. - [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. ## 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.