UK Electrical Symbols: Complete BS EN 60617 Reference (50+ Symbols)

Electrical symbols are the universal language of electrical installation. Every circuit diagram, wiring plan, and installation drawing uses standardised symbols from BS EN 60617 to represent components, connections, and wiring methods. If you cannot read these symbols, you cannot interpret drawings — and if you cannot interpret drawings, you cannot install or inspect electrical systems.

This guide covers every electrical symbol you need to know for City & Guilds qualifications and professional practice, organised by category. Whether you are studying for the 2365 Diploma, preparing for the 2391 Inspection & Testing exam, or reading drawings on site, this is your reference.

Switches are among the most common symbols on installation drawings. The base symbol is a circle with a line, and variations indicate the switch type.

• ✓One-way switch (single pole): a circle with a single diagonal line — controls a circuit from one location
• ✓Two-way switch: a circle with two diagonal lines — used in pairs to control a circuit from two locations (e.g., top and bottom of stairs)
• ✓Intermediate switch: a circle with three diagonal lines — used between two-way switches for three or more control points
• ✓Dimmer switch: the switch symbol with a "D" inside the circle
• ✓Pull-cord switch: the switch symbol with "PC" or a cord line — used in bathrooms and other special locations
• ✓Key-operated switch: the switch symbol with a "K" — used for security or isolation purposes
• ✓Time delay switch: the switch symbol with "TD" — common in communal area lighting
• ✓Double pole switch: two parallel lines through the circle — isolates both line and neutral

Socket outlet symbols are based on a semicircle. The number of vertical lines indicates the number of gangs.

• ✓Single socket outlet: a semicircle with one vertical line
• ✓Twin (double) socket outlet: a semicircle with two vertical lines
• ✓Switched socket: the socket symbol with a line through it representing the switch
• ✓Unswitched socket: the basic socket symbol without a switch line
• ✓Socket with USB charging: the socket symbol with "USB" annotation
• ✓Floor socket: the socket symbol inside a rectangle or with an "F" annotation
• ✓Weatherproof socket: the socket symbol with "WP" or inside a triangle (IP-rated enclosure)
• ✓Dedicated circuit socket: the socket symbol with a triangle or "DC" — indicates a separate circuit for that socket

Lighting symbols represent different fixture types. The base symbol varies depending on the fitting style.

• ✓Ceiling light point: a circle with lines radiating outward (like a sun) — the most common lighting symbol
• ✓Wall light (bracket): a half-circle with radiating lines against a wall line
• ✓Pendant light: the ceiling light symbol with a line dropping down
• ✓Fluorescent fitting: a rectangle with a line through it — length indicates single or twin tube
• ✓LED panel / LED batten: a rectangle with "LED" or a specific LED symbol annotation
• ✓Recessed downlight: a circle with a cross inside — indicates a fixture recessed into the ceiling
• ✓Spotlight: the light symbol with an arrow indicating the direction of illumination
• ✓Emergency light: the light symbol with "EM" or a specific emergency lighting annotation — maintained or non-maintained
• ✓Exterior / bulkhead light: the light symbol with "EX" or "BH" annotation, or inside a square for IP-rated
• ✓PIR sensor: a triangle with radiating lines — passive infrared motion sensor for automatic lighting

Protective device symbols appear on consumer unit schedules, schematic diagrams, and distribution board layouts.

• ✓Fuse: a rectangle or a line with a small rectangle in the middle
• ✓MCB (miniature circuit breaker): a rectangle with a diagonal line or a specific MCB symbol — includes the rating (e.g., B32, C16)
• ✓RCD (residual current device): a rectangle with a test button symbol and the rated residual current (e.g., 30mA)
• ✓RCBO (RCD + MCB combined): combines both symbols — provides both overcurrent and earth fault protection
• ✓Main switch / isolator: a larger symbol showing a switch that disconnects all poles
• ✓SPD (surge protection device): a lightning bolt symbol or specific SPD notation — required in most installations by the 18th Edition of BS 7671 (Section 443)
• ✓AFDD (arc fault detection device): a specific arc symbol — detects dangerous arcing in circuits

Wiring method symbols show how cables are installed and routed. These appear on installation plans to indicate containment, cable types, and installation methods.

• ✓Single cable: a single line (solid for fixed wiring, dashed for flexible)
• ✓Two cables in the same route: two parallel lines
• ✓Three-core cable: three parallel lines or a single line with "3C" annotation
• ✓Cable in conduit: a line inside a rectangle or with a "C" annotation
• ✓Cable in trunking: a line inside a wider rectangle or with "T" annotation
• ✓Cable tray: a line with a tray symbol underneath
• ✓Cable buried in wall: a dashed line (indicating concealed wiring)
• ✓SWA (steel wire armoured): typically annotated "SWA" on the cable run
• ✓MICC (mineral insulated copper clad): annotated "MI" — used in fire-rated applications. See our guide to UK electrical wiring colours for conductor identification
• ✓Rising main: a vertical line with arrows indicating direction — the main supply cable in a multi-storey building

These symbols represent the main components of an electrical supply system, including the circuit types used in domestic installations.

• ✓Consumer unit (CU): a rectangle with the circuits shown branching off — the heart of a domestic installation
• ✓Distribution board (DB): a larger rectangle with multiple ways — used in commercial and industrial installations
• ✓Meter: a circle with an "M" or "kWh" — the electricity meter
• ✓Main earthing terminal (MET): a specific earth symbol — the connection point for all protective conductors
• ✓Earth electrode: three horizontal lines decreasing in size (like a triangle) — a rod or plate driven into the ground
• ✓Equipotential bonding: a line connecting to the earth symbol — main bonding and supplementary bonding connections
• ✓Junction box: a filled circle or dot at the intersection of two or more cables
• ✓Connection / terminal: a small circle or dot where conductors join

Related Course

Level 2 Diploma (2365)

Learn to read and draw all standard electrical symbols in the Level 2 Diploma

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These symbols appear in specific contexts such as fire alarm systems, data installations, and special locations.

• ✓Smoke detector: a circle with "SD" or a specific smoke detector symbol
• ✓Heat detector: a circle with "HD"
• ✓Fire alarm call point: a square with "CP" — the break glass unit
• ✓Fire alarm sounder: a bell symbol or "S" in a circle
• ✓Emergency stop: a circle with a cross — for motor isolation
• ✓Motor: a circle with an "M" — may include kW rating
• ✓Transformer: two coils (circles or waves) side by side
• ✓Fan / extract: a circle with "F" or a fan blade symbol — used for bathroom extractors, kitchen extractors
• ✓Cooker control unit: a specific symbol or "CCU" annotation — usually a 45A DP switch with socket
• ✓Electric vehicle charge point: "EVCP" or a specific EV symbol — increasingly common on new installation drawings
• ✓Solar PV array: a rectangle with "PV" — the generation point for solar photovoltaic systems

Knowing individual symbols is only half the skill. You also need to understand how they combine on installation drawings to represent complete circuits. Here are the key principles:

• ✓Floor plans show the physical location of accessories, lights, and equipment — drawn to scale or annotated with dimensions
• ✓Circuit diagrams show the electrical connections schematically — not to scale, focused on function
• ✓Wiring diagrams show the physical cable routes and terminations — used by installers to run cables
• ✓Block diagrams show the high-level system architecture — used for complex installations to show how subsystems connect
• ✓A single installation may have all four types of drawing — you must be able to read and cross-reference them

Tips for reading drawings in exams

• ✓Look at the legend/key first — it defines any non-standard symbols used on that drawing
• ✓Follow the circuit from the consumer unit outward — trace the line of each conductor
• ✓Count switch lines to identify switch types (1 = one-way, 2 = two-way, 3 = intermediate)
• ✓Note cable sizes and protective device ratings — these are usually annotated on the drawing
• ✓Check for dotted lines indicating switching connections (strappers between two-way switches)

Related Course

Inspection & Testing (2391)

The 2391 exam requires you to interpret drawings and produce schematic diagrams

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Here is how electrical symbols are tested across the key qualifications:

2365 Level 2 Diploma

Unit 202 (Principles of Electrical Science) and the practical assignments require you to identify symbols on drawings and draw basic circuit diagrams. You need to know all standard switch, socket, lighting, and protective device symbols.

2365 Level 3 Diploma

Level 3 builds on Level 2 by requiring you to design circuits and produce installation drawings. You need to select appropriate symbols, draw circuit schematics, and create wiring diagrams for complex circuits including two-way and intermediate switching, ring circuits, and three-phase supplies.

18th Edition (2382)

The 18th Edition exam includes questions with circuit diagrams that use standard symbols. You need to interpret these diagrams to answer questions about protection, disconnection times, and regulation compliance.

Inspection & Testing (2391)

The 2391 exam heavily tests your ability to read installation drawings and produce schematic diagrams. You may be asked to identify faults from a drawing, complete a circuit diagram, or draw the schematic for a circuit described in words.