NC
Normally closed contact
A contact shown closed in the normal state defined for its device.
Schematic
Symbols · NO
Normally open contact
A contact shown open in the normal state defined for its device.
Schematic · NO
What it represents
A normally open contact is open in the normal state defined for the device. Operating its relay, pushbutton or other parent device may close the contact. The meaning of normal must be established from the drawing convention and equipment documentation; it is not necessarily the current live condition of the installation.
A schematic usually identifies the parent device and the relevant terminals. Several contact representations can belong to one relay or contactor. Cross-references connect those representations to their coil or parent equipment.
How to read it
- Read the parent device identifier before interpreting the contact function.
- Check the terminal identifiers and the state convention in the drawing legend.
Information to show or reference
- Identify the parent coil or actuator.
- Use the documented terminal designation.
- Cross-reference other contacts belonging to the same device.
A distinction that matters
Normally open describes the stated normal condition. A position indication or operating snapshot may use a different state convention.
Sources you can follow
These public references support the explanation and provide further detail. Their graphics and downloadable files remain with their publishers.
Relays and contacts: public symbol reference
Public normally open relay contact categories.
About this graphic
This illustration was authored independently by Elora Grid to explain the concept. It is not reproduced from a customer drawing, an official standard graphic or a manufacturer CAD file. Its correspondence to an exact IEC or IEEE symbol identifier has not been certified.
SVG and DXF downloads contain this original artwork. DXF uses unscaled drawing units; a GA envelope supplies no product dimensions, clearances or fabrication information. Original artwork is available under CC BY 4.0. Third-party references retain their own terms.
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A pushbutton contact normally shown open before actuation.
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