[ ELECTRICAL SYMBOLS · COMPARISON ]
IEC vs ANSI electrical symbols
Most electrical symbols look alike in IEC 60617 and ANSI / IEEE 315. The ones that differ are the ones that matter most in control circuits: resistors, contacts, coils, push buttons, fuses and breakers.
Passive components
All passive componentsSymbolANSI / IEEEIEC 60617Difference
Variable resistorANSI: A zigzag with a diagonal arrow through it. IEC: A rectangle with a diagonal arrow through it.
PotentiometerANSI: A zigzag with an arrow pointing at it from the side. IEC: A rectangle with an arrow pointing at it.
Polarised capacitorANSI: One straight and one curved plate. The curved plate is negative, and a plus sign marks the positive side. IEC: Two straight plates with a plus sign on the positive side. Some drawings show the negative plate as a filled or open rectangle.
TransformerS00841ANSI: Two coils facing each other. Two straight lines between them show an iron core. IEC: Two overlapping circles. The coil form is also allowed in IEC 60617.
Semiconductors
All semiconductorsSymbolANSI / IEEEIEC 60617Difference
NPN transistorANSI: Base bar, collector and emitter, with the emitter arrow pointing out, usually inside a circle. IEC: The same lines and outward arrow, usually without the circle.
PNP transistorANSI: The emitter arrow points in towards the base, usually inside a circle. IEC: The same lines and inward arrow, usually without the circle.
Switches and relays
All switches and relaysSymbolANSI / IEEEIEC 60617Difference
Push button (NO)ANSI: Two terminals with a bridging bar above them, not touching, and a plunger. IEC: A make contact with a dashed link to the push-button operator.
Push button (NC)ANSI: Two terminals with a bridging bar below them, touching, and a plunger. IEC: A break contact with a dashed link to the push-button operator.
Relay coilS00305ANSI: A circle with the relay designator inside, such as CR or M for a motor starter. IEC: A rectangle, with the designator such as K1 beside it.
Normally open contactS00227ANSI: Two parallel lines, as on a ladder diagram. It looks like a capacitor, so read it in context. IEC: A hinged blade drawn open.
Normally closed contactS00229ANSI: Two parallel lines with a diagonal line through them. IEC: A blade resting against a fixed contact with a short upright.
Power, protection and ground
All power, protection and groundSymbolANSI / IEEEIEC 60617Difference
FuseS00362ANSI: An S-shaped curve in the wire. A rectangle is also used. IEC: A rectangle with the wire running through it.
Circuit breakerS00287ANSI: Two terminals with an arc above them. IEC: A switch blade with a cross on the fixed contact.
Loads, meters and wiring
All loads, meters and wiringSymbolANSI / IEEEIEC 60617Difference
LampS00965ANSI: A circle with a filament loop inside. Pilot lights are also drawn as a circle with rays or a colour letter. IEC: A circle with a cross inside.
Wire junctionSameThe same dot. IEC prefers T-junctions, so a four-way joint is often drawn as two Ts.
Wires crossingANSI: A plain crossing, or on older drawings a small hop of one wire over the other. IEC: A plain crossing with no dot.
The differences that matter
| Device | ANSI / IEEE 315 | IEC 60617 |
|---|---|---|
| Resistor | Zigzag | Rectangle |
| Normally open contact | Two parallel lines | Hinged blade, open |
| Normally closed contact | Two parallel lines with a diagonal | Blade against a fixed contact |
| Relay coil | Circle with designator (CR, M) | Rectangle, designator K |
| Fuse | S-curve or rectangle | Rectangle with the wire through it |
| Circuit breaker | Arc over two terminals | Switch with a cross |
| Lamp | Circle with filament | Circle with a cross |
| Transistor | Usually in a circle | Usually without a circle |
Which one is on your drawing?
Look at a resistor or a relay: a zigzag and circles mean US practice; rectangles mean IEC. Designators help too: K1, Q1 and F1 point to IEC; CR1, M and FU1 to US practice. Many international projects mix the two, so the legend sheet is the final word.
Frequently asked questions
What is the difference between IEC and ANSI electrical symbols?
Mostly resistors, contacts, coils, fuses, breakers and lamps. ANSI draws a resistor as a zigzag and contacts as parallel lines; IEC draws a resistor as a rectangle and contacts as blades.
Are capacitor and diode symbols the same in IEC and ANSI?
Yes. Capacitors, diodes, LEDs, batteries, grounds, motors and meters are drawn the same way in both.
Every relay, breaker and motor on your schematics, tested before energisation.Deskely holds the inspection and test records and punch items for every electrical and instrument tag on your project, checked against the register as they are signed.
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The symbols on this page were drawn by Deskely and are free to use. Standards are revised and every project issues its own legend sheets, which take precedence.