# PEN conductor mark Canonical URL: https://eloragrid.ai/symbols/iec-pen-conductor-mark Publisher: Elora Grid Updated: 2026-10-28 Lookup label: PEN Drawing use: SLD, Schematic Reference families: IEC ## Symbol convention Convention: IEC Form: PEN conductor identification on a conductor group Independent IEC-context illustration; not certified IEC geometry. A mark identifying a combined protective and neutral conductor, as used in TN-C sections of a supply. ## In plain English ### What does PEN conductor mark mean? The PEN mark identifies one conductor that performs both the protective and neutral functions. It appears in TN-C and TN-C-S arrangements, typically between the supply transformer and the main switchboard, where the PEN is later separated into N and PE at a defined point. ### A simple example A PEN conductor must not be switched or isolated on its own, and once separated into N and PE the two must not be rejoined downstream. A drawing that shows a PEN mark should therefore also show the separation point clearly. The mark says nothing about minimum conductor size, which local wiring rules set for PEN conductors. ### What the drawings help you do Find the point where the PEN is split into N and PE. Check that no switching device opens the PEN conductor alone. A PEN conductor combines N and PE functions; a neutral mark shows a conductor that has no protective role. ### This particular reference A mark identifying a combined protective and neutral conductor, as used in TN-C sections of a supply. A PEN conductor combines N and PE functions; a neutral mark shows a conductor that has no protective role. ### Terms - Winding: A coil of conductor inside an electrical machine or transformer. - 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. - [Definition of standardised earthing schemes](https://www.electrical-installation.org/enwiki/Definition_of_standardised_earthing_schemes) - [Earthing connections](https://www.electrical-installation.org/enwiki/Earthing_connections) ## What it represents The PEN mark identifies one conductor that performs both the protective and neutral functions. It appears in TN-C and TN-C-S arrangements, typically between the supply transformer and the main switchboard, where the PEN is later separated into N and PE at a defined point. A PEN conductor must not be switched or isolated on its own, and once separated into N and PE the two must not be rejoined downstream. A drawing that shows a PEN mark should therefore also show the separation point clearly. The mark says nothing about minimum conductor size, which local wiring rules set for PEN conductors. ## How to read it - Find the point where the PEN is split into N and PE. - Check that no switching device opens the PEN conductor alone. ## Information to show or reference - Show the PEN to N and PE separation point. - Avoid single-pole switching of the PEN. - Confirm PEN sizing against the applicable wiring rules. ## Important distinction A PEN conductor combines N and PE functions; a neutral mark shows a conductor that has no protective role. ## Facts - Graphic cue: Combined neutral and earth mark on one stroke - Letter code: PEN - Scheme context: TN-C and TN-C-S sections - Preview: Original educational illustration; consult the publisher and applicable standard for the exact graphic ## Public references - [Definition of standardised earthing schemes](https://www.electrical-installation.org/enwiki/Definition_of_standardised_earthing_schemes) — Schneider Electric, Electrical Installation Guide. Public installation-guide definitions of TN-C and TN-C-S schemes. - [Earthing connections](https://www.electrical-installation.org/enwiki/Earthing_connections) — Schneider Electric, Electrical Installation Guide. Public guide to earthing connection elements. ## 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.