Understand the difference.

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

Lamp

Symbols

Indicator lamp

An indicator lamp shows an operating condition defined by its circuit and label. The generic representation identifies an indicating element; it does not define what illumination means, the supply voltage or whether the device is continuously lit or flashing.

Drawing use

Schematic

Application

Control circuits

Reference family

IEC / IEEE / ANSI

A distinction that matters

An indication mark does not establish that equipment is safe, isolated or de-energised. Its meaning comes from the full circuit and operating documentation.

Full referenceAdd to legend

NO

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 referenceAdd to legend

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