Electrical wire diagrams are the roadmaps of electrical systems. Whether you’re working on automotive repair, home wiring, or industrial electrical systems, understanding the symbols used in these diagrams is essential. This guide from keyfobprog.com, your trusted automotive repair resource, will help you decipher Electrical Wire Diagram Symbols, ensuring you can accurately read and implement electrical schematics.
We’ll break down common electrical symbols, categorized for easy understanding, and provide clear descriptions to help you master this crucial skill.
Location Symbols for Installations
These symbols represent the physical location or mounting of electrical components within a system.
| Symbol | Description |
|---|---|
| Load, General Symbol: This symbol broadly represents any electrical load, which is a component that consumes electrical power. The specific type of load should be detailed separately. | |
| Motor Starter, General Symbol: Indicates a motor starter, a device used to protect and start an electric motor. Specific details about the starter type should be indicated alongside this symbol. | |
| Socket-outlet, General Symbol: Represents a standard electrical socket outlet where devices can be plugged in. | |
| Twin Socket-outlet, General Symbol: Indicates a double socket outlet, providing two points to plug in devices. | |
| Switched Socket-outlet: A socket outlet that includes an integrated switch to control the power supply to the socket. | |
| Twin Switched Socket-outlet: A double socket outlet, both points of which are controlled by an integrated switch. | |
| Switch, General Symbol: This is a generic symbol for a switch, a device used to open or close an electrical circuit. | |
| 2-way Switch, Single Pole: A single-pole, double-throw switch, often used in lighting circuits to control a light from two different locations. | |
| Intermediate Switch: Used in conjunction with 2-way switches to control a light from three or more locations. | |
| Pull Switch, Single-pole: A switch activated by pulling a cord or chain, typically a single-pole switch. | |
| Push Button: A momentary switch activated by pressing a button. | |
| Clock, General Symbol: Represents a timing device or clock within the electrical system. | |
| Bell (Audible): Symbol for an electrical bell, an audible signaling device. | |
| Buzzer (Audible): Represents an electrical buzzer, another type of audible signaling device, often with a different tone than a bell. | |
| Siren (Audible): Symbol for an electrical siren, used for alarms or warning signals. | |
| Horn: Represents an electrical horn, similar to a siren but often used for vehicle signaling. | |
| Telephone Handset, General Symbol: Represents a telephone handset or communication device within the system. |
Popular Electrical Wiring Diagram Symbols
These are some of the most frequently encountered symbols in electrical schematics.
Making and Breaking Current
These symbols pertain to devices that control the flow of electrical current by either connecting or disconnecting circuits.
| Symbol | Description |
|---|---|
| Switch: (As seen before, but important to reiterate) A device for opening or closing an electrical circuit, interrupting or allowing current flow. | |
| Switch-fuse: A combination device integrating a switch and a fuse for both circuit control and overcurrent protection. | |
| Fuse-switch: Similar to a switch-fuse, also combining a switch and fuse in one unit. |
Isolating Symbols
Isolating symbols represent devices designed to safely disconnect parts of an electrical circuit for maintenance or safety.
| Symbol | Description |
|---|---|
| Isolator (Disconnector), General Symbol: A device used to disconnect a circuit or equipment from a power source, ensuring safety during maintenance. | |
| Disconnector – fuse (fuse combination unit): Combines the function of a disconnector with a fuse, providing both isolation and overcurrent protection. | |
| Fuse – disconnector: Similar to a disconnector-fuse, another variation of a combination unit. |
Making, Breaking and Isolating Symbols
These symbols represent components that offer combined functionality – controlling, interrupting, and safely isolating circuits.
| Symbol | Description |
|---|---|
| Switch – disconnector: A device that functions as both a switch and a disconnector, offering circuit control and isolation capabilities. | |
| Switch – disconnector – fuse (fuse combination unit): A comprehensive device combining a switch, disconnector, and fuse for control, isolation, and overcurrent protection. | |
| Fuse – switch – disconnector: Another permutation of the combined switch, disconnector, and fuse unit. | |
| Capacitor, General Symbol: Represents a capacitor, a component that stores electrical energy in an electric field. | |
| Inductor, Coil, Winding or Choke: Symbol for an inductor, also known as a coil or choke, which stores energy in a magnetic field. | |
| Inductor, Coil, Winding or Choke with Magnetic Core: An inductor with a magnetic core, which increases its inductance. | |
| Semi Conductor Diode – General Symbol: Represents a semiconductor diode, a component that allows current to flow primarily in one direction. | |
| Microphone: Symbol for a microphone, a transducer that converts sound waves into electrical signals. | |
| Loudspeaker: Represents a loudspeaker, which converts electrical signals back into sound waves. | |
| Antenna, General Symbol: Symbol for an antenna, used to transmit or receive radio waves. | |
| Machine, General Symbol: A general symbol for an electrical machine, like a motor or generator. Function is indicated by letters (M=Motor, G=Generator). | |
| Generator, General Symbol: Specifically represents a generator, a machine that converts mechanical energy into electrical energy. | |
| Indicating Instrument, General Symbol: A general symbol for a measuring instrument. Function is indicated by letters (V=Voltmeter, A=Ammeter). | |
| Integrating Instrument or Energy Meter: Symbol for an instrument that measures and accumulates a quantity over time, such as an energy meter (Watt-hour or Volt-ampere reactive hour). | |
| Lamp, or Signal Lamp, General Symbol: A general symbol for a lamp or indicating light. |
Lamps & Lighting Symbols
These symbols specifically relate to lamps and lighting fixtures in electrical diagrams.
| Symbol | Description |
|---|---|
| Lamp (Standard): A standard symbol for a lamp, representing a light source. | |
| Lamp Standard: (Redundant description, same as above). | |
| Filament Lamp: Represents an incandescent lamp using a filament to produce light. | |
| Lamp (Flashing): Indicates a flashing lamp or beacon light. | |
| Lighting Outlet Position – General Symbol: Indicates the location of a lighting outlet or fixture in a wiring diagram. | |
| Fluorescent Luminaire: Symbol for a fluorescent light fixture. | |
| Wall Mounted Luminaire: Represents a light fixture designed for wall mounting. | |
| Self – contained Emergency Lighting Luminaire: Symbol for a self-contained emergency light fixture, typically battery-backed. | |
| Emergency Lighting Luminaire (or special circuit): Represents an emergency light fixture, which may be part of a dedicated emergency circuit. | |
| Light Emitting Diode (LED): Symbol for a Light Emitting Diode (LED), a highly efficient light source. |
Connectors and Earthing Symbols
These symbols are crucial for representing connections and grounding in electrical systems, ensuring safety and proper function.
| Symbol | Description |
|---|---|
| Plug Male: Represents the male part of a plug connector. | |
| Socket (plug female): Represents the female part of a socket connector. | |
| Coax Plug Male: Symbol for a male coaxial plug connector, used for coaxial cables. | |
| Slow Operating Relay – Delay On: (Misplaced description, belongs to relay section, but symbol image is for Coax Plug) Likely incorrect association in original source. Should be Coax Socket Female. | |
| Wire Connections (Two Wires): Indicates a connection between two wires. | |
| Wire Connections (crossed): Represents wires crossing and being connected. | |
| Wires Crossing (Not Connected): Indicates wires crossing paths but not electrically connected. | |
| Terminal Connector: Symbol for a terminal connector, used to join wires or components. | |
| Terminal Block: Represents a terminal block, a set of multiple terminal connectors. | |
| Earth Connection: General symbol for an earth or ground connection, providing a path to ground for safety. | |
| Noiseless Earth: Symbol for a noiseless or clean earth connection, used in sensitive electronic circuits to minimize noise. | |
| Protective Earth: Represents a protective earth connection, a safety ground to protect against electrical shock. | |
| Chassis Earth: Symbol for a chassis earth connection, grounding to the metal chassis or frame of equipment. | |
| Equipotentiality: Represents equipotential bonding, connecting different conductive parts to minimize voltage differences. |
General Electrical Symbols
These symbols cover a range of common components used across various electrical applications.
| Symbol | Description |
|---|---|
| Ammeter: Symbol for an ammeter, an instrument used to measure electric current in amperes. | |
| Voltmeter: Symbol for a voltmeter, used to measure electrical potential difference in volts. | |
| Circuit Breaker: Represents a circuit breaker, a protective device that automatically interrupts current flow in case of an overload or fault. | |
| Selector Switch: A switch with multiple positions, allowing selection between different circuits or functions. | |
| Normally Open (N/O): (Descriptive text, not a symbol) Indicates a contact that is open in its normal, unactuated state. | |
| Normally Closed (N/C): (Descriptive text, not a symbol) Indicates a contact that is closed in its normal, unactuated state. | |
| Contactor (N/C): Symbol for a normally closed contact of a contactor, an electrically controlled switch. | |
| Contactor (N/O): Symbol for a normally open contact of a contactor. | |
| Limit Switch: Represents a limit switch, a switch activated by a physical object reaching a certain limit of travel. | |
| Thermal Overcurrent: Symbol for a thermal overcurrent relay or device, protecting against excessive current based on temperature. | |
| Mechanical Interlock: Represents a mechanical interlock, a mechanism that prevents conflicting operations or ensures sequential operation. | |
| Voltage Transformer: Symbol for a voltage transformer, used to step up or step down voltage levels in a circuit. | |
| Potentiometer: Represents a potentiometer, a variable resistor used to control voltage or current. | |
| Solenoid Valve: Symbol for a solenoid valve, an electrically controlled valve used to regulate fluid or air flow. |
Contacts and Switches Symbols
These symbols detail various types of electrical contacts and switches, often specifying their normal states (Normally Open or Normally Closed).
| Symbol | Description |
|---|---|
| Normally Open Contact (N/O): A contact that is open in its normal state and closes when actuated. | |
| Normally Closed Contact (N/C): A contact that is closed in its normal state and opens when actuated. | |
| Change Over or 2-way Contact Made position: Represents a changeover contact or single-pole double-throw (SPDT) contact in the made (closed) position. | |
| Fused Switch Open Contact (N/O): Symbol for a normally open contact of a fused switch in the open position. | |
| Limit Switch (N/O): Symbol for a normally open limit switch. | |
| Limit Switch (N/C): Symbol for a normally closed limit switch. | |
| Flow Switch (N/O): Symbol for a normally open flow switch, activated by fluid flow. | |
| Flow Switch (N/C): Symbol for a normally closed flow switch. | |
| Time Delay (N/O) Delay on Closing: Symbol for a normally open time-delay contact that delays closing after actuation. | |
| Time Delay (N/O) Delay on re-opening: Symbol for a normally open time-delay contact that delays re-opening after de-actuation. | |
| Thermal Switch – Overload (N/O): Symbol for a normally open thermal overload switch, activated by excessive temperature due to overload. | |
| Thermal Switch – Overload (N/C): Symbol for a normally closed thermal overload switch. | |
| Temperature Switch (N/O): Symbol for a normally open temperature switch, activated at a set temperature. | |
| Temperature Switch (N/C): Symbol for a normally closed temperature switch. | |
| Pressure Switch (N/O): Symbol for a normally open pressure switch, activated by pressure. | |
| Pressure Switch (N/C): Symbol for a normally closed pressure switch. |
Push-button Symbols
These symbols specifically represent push-button switches and their different configurations.
| Symbol | Description |
|---|---|
| Normally Open PB (N/O): Symbol for a normally open push-button switch. | |
| Normally Closed PB (N/C): Symbol for a normally closed push-button switch. | |
| Emergency Stop PB (N/O) Indication Contact: Symbol for a normally open emergency stop push-button, including an indication contact. | |
| Emergency Stop PB (N/C): Symbol for a normally closed emergency stop push-button. | |
| Pull Switch (N/O): Symbol for a normally open pull switch (push-button type). | |
| Pull Switch (N/C): Symbol for a normally closed pull switch. | |
| Turn/Rotary Switch (N/O): Symbol for a normally open turn or rotary switch (push-button type). | |
| Turn/Rotary Switch (N/C): Symbol for a normally closed turn or rotary switch. |
Coils and Relays Symbols
These symbols represent coils and relays, essential components for control and switching in electrical circuits.
| Symbol | Description |
|---|---|
| Electrical Symbols – Coils and Relays: (Heading, not a symbol). | |
| The following table provides the commonly used electrical wiring schematic symbols for coils and relays which comply with the IEC and BS Electrical Symbols: (Descriptive text, not a symbol). | |
| Contractor Coil: Symbol for a contactor coil, the electromagnetic coil that actuates a contactor. | |
| Relay with AC Supply: Symbol for a relay designed to operate with an AC power supply. | |
| Slow Release Relay Delay Off: Symbol for a slow-release relay with a delay in de-energizing (delay-off). | |
| General Relay (DC Supply): Symbol for a general-purpose relay designed for a DC power supply. | |
| Slow Operating Relay Delay On: Symbol for a slow-operating relay with a delay in energizing (delay-on). | |
| Mechanically Latched Relay: Symbol for a mechanically latched relay, which remains in its last energized state even after power is removed. |
Semi Conductor Symbols
This section seems to be a duplicate from the previous section “Coils and Relays Symbols” in the original text. It should ideally list semiconductor symbols like transistors, diodes, etc., but it currently repeats the coil and relay symbols. It’s important to note this discrepancy from the original source if accuracy is paramount. For the purpose of improving the article, this section should be corrected to list actual semiconductor symbols. However, as per instructions to stay true to the original, I will maintain the duplicated content for now.
| Symbol | Description |
|---|---|
| Contractor Coil: (Duplicate entry from “Coils and Relays”) Symbol for a contactor coil. | |
| Relay with AC Supply: (Duplicate entry) Symbol for a relay with AC supply. | |
| Slow Release Relay Delay Off: (Duplicate entry) Symbol for a slow release relay delay off. | |
| General Relay (DC Supply): (Duplicate entry) Symbol for a general relay (DC Supply). | |
| Slow Operating Relay Delay On: (Duplicate entry) Symbol for slow operating relay delay on. | |
| Mechanically Latched Relay: (Duplicate entry) Symbol for mechanically latched relay. |
Other Electrical Symbols
This category includes miscellaneous symbols that don’t fit neatly into the previous categories, but are still important in electrical diagrams.
| Symbol | Description |
|---|---|
| Three-phase winding – Star: Represents a three-phase electrical winding in a star (wye) configuration. | |
| Changer, General Symbol Converter, General Symbol: General symbol for a changer or converter, devices that alter electrical characteristics. | |
| Notes: (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 change. (Explanatory notes for the ‘Changer’ symbol). | |
| Rectifier: Symbol for a rectifier, a device that converts AC to DC electrical power. | |
| Inverter: Symbol for an inverter, which converts DC to AC electrical power. | |
| Primary cell – longer line positive, shorter line negative: Symbol for a primary cell (battery), indicating polarity with line lengths. | |
| Battery: General symbol for a battery, a collection of one or more cells. | |
| Fuse link, rated current in amperes: Symbol for a fuse link, with the rated current value typically indicated alongside in amperes. |
Understanding these electrical wire diagram symbols is a fundamental step in electrical work and automotive repair. By familiarizing yourself with these symbols, you can confidently interpret electrical schematics and troubleshoot electrical systems effectively. Keep this guide from keyfobprog.com handy as your reference to electrical wire diagram symbols.
