{"schemaVersion":1,"slug":"current-test-switch-with-shorting","name":"Current test switch with shorting contact","kind":"symbol","abbreviation":"TS","aliases":["CT test switch","shorting test switch","current switch with make-before-break"],"category":"measurement-protection","drawingTypes":["Schematic"],"referenceFamilies":["IEEE / ANSI","Manufacturer"],"summary":"Panel test switch for CT circuits that shorts the CT side before opening the relay side, with a test jack between.","description":["Panel-mounted test switches used in North American practice often combine a knife switch with a shorting contact for each CT circuit. Opening the switch first shorts the CT secondary and then isolates the relay or meter, so a test set can be connected without exposing the CT to an open circuit.","Current test switches are usually grouped with potential test switches and trip-isolating switches on one assembly. The symbol shows a single pole, and the full assembly arrangement, including which poles are current and which are potential, must be read from the panel wiring diagram."],"readingNotes":["Confirm the shorting contact is on the CT side.","Read the switch sequence for the assembly."],"drawingChecklist":["Show shorting contact","Identify CT and relay sides","Reference assembly pole list"],"distinction":"A current test switch shorts the CT on opening; a potential test switch simply opens the voltage circuit.","facts":[{"label":"Sequence","value":"Short CT, then open relay side"},{"label":"Common mounting","value":"Front of relay or meter panel"},{"label":"Preview","value":"Functional illustration of the device role; not a product footprint or certified standard graphic"}],"references":[{"sourceId":"ct-terminals","relevance":"Public manufacturer range of transformer and test terminals for measuring and protection circuits."},{"sourceId":"ieee-315","relevance":"IEEE graphic-symbol standards context; no standard glyph is reproduced."}],"related":["potential-test-switch","relay-test-block","ct-test-terminal"],"artwork":"s28-current-test-switch-with-shorting","publishedOn":"2026-10-28","updatedOn":"2026-10-28","provenance":"independent-public-research","plainEnglish":{"title":"What does Current test switch with shorting contact mean?","introduction":"Panel-mounted test switches used in North American practice often combine a knife switch with a shorting contact for each CT circuit. Opening the switch first shorts the CT secondary and then isolates the relay or meter, so a test set can be connected without exposing the CT to an open circuit.","example":"Current test switches are usually grouped with potential test switches and trip-isolating switches on one assembly. The symbol shows a single pole, and the full assembly arrangement, including which poles are current and which are potential, must be read from the panel wiring diagram.","drawings":"Confirm the shorting contact is on the CT side. Read the switch sequence for the assembly. A current test switch shorts the CT on opening; a potential test switch simply opens the voltage circuit.","terms":[{"name":"Normally open / normally closed","meaning":"The contact state in the normal condition defined for the drawing."},{"name":"Coil","meaning":"A wound conductor that can produce a magnetic field when energised."},{"name":"Rating","meaning":"A value stating the conditions for which equipment is specified."}],"diagram":"flow","steps":["Identify the device and form","Read the connections and state","Check the equipment reference"],"caption":"A guide to reading this reference. The original symbol illustration and its drawing notes appear below; these boxes are not a wiring diagram.","sources":[{"label":"Transformer terminals for measuring and test circuits","url":"https://www.phoenixcontact.com/en-ie/products/terminal-blocks/transformer-terminal-blocks?p=7"},{"label":"IEEE/ANSI 315-1975: graphic symbols for electrical and electronics diagrams","url":"https://standards.ieee.org/ieee/315/515/"}],"detail":"Panel test switch for CT circuits that shorts the CT side before opening the relay side, with a test jack between. A current test switch shorts the CT on opening; a potential test switch simply opens the voltage circuit.","profileId":"reviewed-symbol-20261028"},"url":"https://eloragrid.ai/symbols/current-test-switch-with-shorting","illustration":{"url":"https://eloragrid.ai/tools/electrical-library/illustrations/current-test-switch-with-shorting.svg","scope":"Original educational concept; not an official standard graphic or product footprint","license":"https://creativecommons.org/licenses/by/4.0/"},"sources":[{"id":"ct-terminals","title":"Transformer terminals for measuring and test circuits","publisher":"Phoenix Contact","url":"https://www.phoenixcontact.com/en-ie/products/terminal-blocks/transformer-terminal-blocks?p=7","type":"manufacturer","scope":"Current-transformer test terminals and leading short-circuit arrangements. Use the selected product's instructions for any intervention.","checkedOn":"2026-10-13","reuse":"link-only","relevance":"Public manufacturer range of transformer and test terminals for measuring and protection circuits."},{"id":"ieee-315","title":"IEEE/ANSI 315-1975: graphic symbols for electrical and electronics diagrams","publisher":"IEEE Standards Association","url":"https://standards.ieee.org/ieee/315/515/","type":"standard","scope":"Graphic symbols and designation letters. IEEE lists this edition as Inactive-Reserved; it is a historical reference, not a claim of current compliance.","checkedOn":"2026-10-13","reuse":"link-only","relevance":"IEEE graphic-symbol standards context; no standard glyph is reproduced."}]}