# ANSI/IEEE Key-operated normally-closed switch form Canonical URL: https://eloragrid.ai/symbols/ansi-key-operated-normally-closed-switch Publisher: Elora Grid Updated: 2026-10-28 Lookup label: KEY NC Drawing use: Schematic Reference families: IEEE / ANSI, Manufacturer ## Symbol convention Convention: IEEE / ANSI Form: Key Switch, Normally Closed Autodesk IEEE Symbol Preview: Miscellaneous Switches, block HPB12KS. Matching functional counterpart linked separately. Independently drawn educational geometry; not a certified IEEE glyph or database identifier. Related representation: [Key-operated normally-closed switch](https://eloragrid.ai/symbols/key-operated-normally-closed-switch) IEEE-library form of key-operated normally-closed switch: a key-operated NC switch opens its reference closed contact through the key mechanism. ## In plain English ### What does ANSI/IEEE Key-operated normally-closed switch form mean? This reference locates key-operated normally-closed switch in Autodesk's IEEE-oriented miscellaneous switches family. A key-operated normally closed switch opens its reference closed contact through the key mechanism. Its access and switching functions must be documented separately. The public library uses HPB12KS for its horizontal representation; this is a vendor block name, not an IEEE standards symbol number. ### A simple example Read the operating mechanism and the contact reference state together. Cross-reference every associated contact to the same device and show which movement, signal or reset changes its condition; the symbol alone does not establish the complete switching sequence. ### What the drawings help you do Read the reference position from the operator schedule. normally closed identifies the contact reference state, not a guarantee of tamper-proof control. The linked functional counterpart explains the same operating role in its own drawing context; agreement of every detailed convention mark is not asserted. ### This particular reference IEEE-library form of key-operated normally-closed switch: a key-operated normally closed switch opens its reference closed contact through the key mechanism. normally closed identifies the contact reference state, not a guarantee of tamper-proof control. ### Terms - Normally open / normally closed: The contact state in the normal condition defined for the drawing. - Signal: Electrical information passed between devices, rather than necessarily the main power supply. - Rating: A value stating the conditions for which equipment is specified. 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. - [Autodesk IEEE Symbol Preview — Miscellaneous Switches](https://help.autodesk.com/cloudhelp/2021/ENU/AutoCAD-Electrical/files/GUID-278F6C21-B1A6-4EA1-A535-E78D53BBD10D.htm) ## What it represents This reference locates key-operated normally-closed switch in Autodesk's IEEE-oriented miscellaneous switches family. A key-operated NC switch opens its reference closed contact through the key mechanism. Its access and switching functions must be documented separately. The public library uses HPB12KS for its horizontal representation; this is a vendor block name, not an IEEE standards symbol number. Read the operating mechanism and the contact reference state together. Cross-reference every associated contact to the same device and show which movement, signal or reset changes its condition; the symbol alone does not establish the complete switching sequence. Read the reference position from the operator schedule. NC identifies the contact reference state, not a guarantee of tamper-proof control. The linked functional counterpart explains the same operating role in its own drawing context; agreement of every detailed convention mark is not asserted. ## How to read it - Read the reference position from the operator schedule. - The preview is an original explanation of this function. Match the actual drawing convention to its legend and the selected equipment documentation. ## Information to show or reference - Define normal key position - State contact action - Reference key-removal restrictions ## Important distinction NC identifies the contact reference state, not a guarantee of tamper-proof control. ## Facts - Convention evidence: Autodesk IEEE Symbol Preview: Miscellaneous Switches; published form: Key Switch, Normally Closed. - Public vendor block: HPB12KS. Vendor library token, not an IEEE symbol number. - Drawing role: Manual operation - Identifier status: The short label is a functional lookup label, not an assigned IEC or IEEE symbol number. Any separately listed Autodesk code is a verified vendor block name. - Artwork scope: Original educational geometry. Exact standard graphics, product ratings and terminal pinouts are not certified. ## Public references - [Autodesk IEEE Symbol Preview — Miscellaneous Switches](https://help.autodesk.com/cloudhelp/2021/ENU/AutoCAD-Electrical/files/GUID-278F6C21-B1A6-4EA1-A535-E78D53BBD10D.htm) — Autodesk. Public IEEE-oriented Miscellaneous Switches table explicitly lists HPB12KS as Key Switch, Normally Closed. This supports the vendor convention context, not reproduction of the publisher graphic. ## 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.