Side-by-side reference

Understand the difference.

Compare the meaning, drawing context and source references of two entries. A similar graphic or shared abbreviation does not establish equivalence.

First referenceCompare with

Symbols

Changeover contact

A changeover contact connects a common terminal to one of two alternative contact paths according to its operating state. Form C and SPDT are terms commonly encountered for this arrangement. The actual terminal numbering and transfer behaviour come from the selected device.

Drawing use: Schematic
Application: Control circuits
Reference family: IEC / IEEE / ANSI

A distinction that matters

Two unrelated NO/NC contacts are not automatically one changeover contact. Confirm whether they share a common connection and operating mechanism.

Full reference

Symbols

Normally open contact

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.

Drawing use: Schematic
Application: Control circuits
Reference family: IEC / IEEE / ANSI

A distinction that matters

Normally open describes the stated normal condition. A position indication or operating snapshot may use a different state convention.

Full reference

Original educational previews. Follow the source references on each full entry for the appropriate standard or selected product.