# Current test switch with shorting contact

Canonical URL: https://eloragrid.ai/symbols/current-test-switch-with-shorting
Publisher: Elora Grid
Updated: 2026-10-28
Lookup label: TS
Drawing use: Schematic
Reference families: IEEE / ANSI, Manufacturer

Panel test switch for CT circuits that shorts the CT side before opening the relay side, with a test jack between.

## In plain English

### What does Current test switch with shorting contact mean?

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.

### A simple 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.

### What the drawings help you do

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.

### This particular reference

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.

### Terms

- Normally open / normally closed: The contact state in the normal condition defined for the drawing.
- Coil: A wound conductor that can produce a magnetic field when energised.
- 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.

- [Transformer terminals for measuring and test circuits](https://www.phoenixcontact.com/en-ie/products/terminal-blocks/transformer-terminal-blocks?p=7)
- [IEEE/ANSI 315-1975: graphic symbols for electrical and electronics diagrams](https://standards.ieee.org/ieee/315/515/)


## What it represents

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.

## How to read it

- Confirm the shorting contact is on the CT side.
- Read the switch sequence for the assembly.

## Information to show or reference

- Show shorting contact
- Identify CT and relay sides
- Reference assembly pole list

## Important distinction

A current test switch shorts the CT on opening; a potential test switch simply opens the voltage circuit.

## Facts

- Sequence: Short CT, then open relay side
- Common mounting: Front of relay or meter panel
- Preview: Functional illustration of the device role; not a product footprint or certified standard graphic

## Public references

- [Transformer terminals for measuring and test circuits](https://www.phoenixcontact.com/en-ie/products/terminal-blocks/transformer-terminal-blocks?p=7) — Phoenix Contact. Public manufacturer range of transformer and test terminals for measuring and protection circuits.
- [IEEE/ANSI 315-1975: graphic symbols for electrical and electronics diagrams](https://standards.ieee.org/ieee/315/515/) — IEEE Standards Association. IEEE graphic-symbol standards context; no standard glyph is reproduced.

## 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.