Standard symbols, units and graphical symbols for general electrical purposes.


The following symbols are extracted mainly from IEC 60617, supplemented by references from other Standards.


General symbols

V Volts
A amperes
Hz Hertz
W Watts
kW Kilowatts
F farads
p.u. per unit
ph phase
p.f. power factor
L line
N neutral
h hours
min minutes
s seconds


Direct Current (or d.c.)
Alternating Current (or a.c.)
2 two-phase alternating current
2N two-phase alternating current with neutral
3 three-phase alternating current
3N three-phase alternating current with neutral
IPXX IP number (See index of protection
Fault (indication of assumed fault location)
Class II appliance (Equipment in which protection against electric shock does not rely on basic insulation only, but in which additional safety precautions such as supplementary insulation are provided, there being no provision for connection of exposed metalwork of the equipment to a protective conductor, and no reliance upon precaution to be taken in the fixed wiring of the installation).
Class III appliance (Equipment in which protection against electric shock relies on supply at SELV and in which voltages higher than those of SELV are not generated)
Safety isolating transformer. Class III equipment must be supplied from a safety isolating transformer to BS 3535. The safety isolating transformer will have this identifying mark upon it.
Isolating transformer
Protective earth, general symbol (preferred to )


Symbols for use in schematic wiring diagram

Transformer, general symbol
General Wiring, with joint
Identification of specific conductors
Operating device, general symbol (coil)
Make contact - normally open
Break contact - normally closed
Manually operated switch, general symbol
Three-phase winding - delta
Three-phase winding - star

Changer, general symbol Converter, general symbol

(1) if the direction of change is not obvious, it may be indicated by an arrowhead on the outline of the symbol.
(2) A symbol or legend indicating the input or output quantity, waveform etc. may be inserted in each half of the general symbol to show the nature of the change

Battery of primary or secondary cell - longer line positive, shorter line negative
Fuse link, rated current in amperes
Capacitor, general symbol
Inductor, coil, winding or choke
Inductor, coil, winding or choke with magnetic core
Semi Conductor Diode - general symbol


Making and breaking current




Isolator (Disconnector), general symbol
Disconnector - fuse (fuse combination unit)
Fuse - disconnector
Circuit-breaker suitable for isolation


Making, breaking and isolating

Switch - disconnector
Switch - disconnector - fuse (fuse combination unit)
Fuse - switch - disconnector



Integrating instrument, or Energy meter
* function
VArh=Volt ampere reactive hour



Location symbols for Installations

Machine general symbol
* function
Motor Starter, general symbol
Star-delta starter
Socket-outlet, general symbol
Switched socket-outlet
Switch, general symbol
2 way switch, single pole
Intermediate switch
Pull switch, single-pole
  Lighting outlet position, general symbol
Fluorescent luminaire, general symbol
Emergency lighting luminaire (or special circuit)
Self-contained emergency lighting luminaire
  Push button with indicator lamp
Lamp, or signal lamp, general symbol
Clock, general symbol
Acoustic signalling device, general symbol (e.g. bell
Telephone handset, general symbol
Antenna, general symbol
Generator, general symbol