Electrical schematic symbols
The shorthand a wiring diagram is written in. Each of these is drawn from scratch in the site's own line style — a symbol is a drawing convention, so learning to read it is half of reading any schematic. What a device must actually connect to, and the colours involved, are set by the code, not by the symbol.
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Single-pole switchOne line broken by a tilted blade. Makes and breaks one conductor. -
Three-way switchOne common on the left, two travellers on the right — a single-pole double-throw. -
Duplex receptacleA circle with two slots — an outlet with two places to plug in. -
GFCI receptacleAn outlet with test and reset buttons — the ground-fault protective device. -
Lamp / luminaireA circle with a cross — a light fixture as a load. -
MotorA circle marked M — a rotating load on the circuit. -
Relay / contactor coilA plain circle — the electromagnet that pulls contacts open or closed. -
Ground / earthThree shrinking bars — a connection to earth for reference and safety. -
Junction boxA square — a box where conductors are joined or pulled. -
FuseA rectangle with a line through it — a one-time overcurrent element. -
Circuit breakerA switch with a small arc — a resettable overcurrent device. -
Conductors joinedA dot at a crossing means the two wires connect; no dot means they only cross.
See the symbols working together in the interactive wiring diagrams, where you can toggle a switch and watch the circuit respond.
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