Electrical symbols
Name the symbol. Get 10 right to finish. Pick US or IEC in the box below.
What does this US (ANSI/IEEE) symbol stand for?
The same parts, two drawing languages
US drawings follow the ANSI/IEEE 315 style. Most of the world uses IEC 60617. The meaning is the same, but some shapes differ, so check which system a drawing uses before you read it. The title block or legend usually says.
| Meaning | US (ANSI/IEEE) | IEC |
|---|---|---|
| Normally open (NO) contact | ||
| Normally closed (NC) contact | ||
| Normally open pushbutton | ||
| Normally closed pushbutton | ||
| Relay or contactor coil | ||
| Indicator lamp (pilot light) | ||
| Resistor | ||
| Motor |
US control drawings put the current flow left to right, so the symbols sit on horizontal wires. IEC drawings usually run top to bottom, so the same symbols stand upright.
Same in both
| Meaning | US (ANSI/IEEE) | IEC |
|---|---|---|
| Capacitor | ||
| Battery or cell | ||
| Diode | ||
| Ground (earth) |
Questions
- What is the difference between ANSI and IEC electrical symbols?
- Mostly the shapes. A resistor is a zigzag on US drawings and a rectangle on IEC drawings. A coil is a circle in a US ladder diagram and a rectangle in IEC. Motors, capacitors, diodes and ground look the same in both.
- How are contacts drawn, open or closed?
- In their rest state: with the coil off and nobody pressing a button. A normally open contact is drawn open, a normally closed contact is drawn closed.
Explained in our own words and checked against several references. For the full rules, see the NEC (NFPA 70), NFPA 79, IEC 60617, IEC 60445 and IEC 81346-2. Your drawing legend always comes first.