Electrical Symbols Chart Reference
Reading a drawing quickly depends on knowing the symbols. Here's a practical reference to the ones you'll meet most on UK installation layouts.
Electrical drawings use standardised symbols so that any electrician can read a layout the same way. UK drawings draw on BS EN 60617 and the older BS 3939, and installation layouts use a familiar set of accessory and distribution symbols.
This guide is a practical reference to the symbols you'll meet most — accessories, lighting, switching, protective devices and distribution — and what each represents on a drawing.
Key takeaways
- UK drawings use symbols from BS EN 60617 and the older BS 3939.
- Accessory symbols cover sockets, fused spurs, switches and outlets on layout drawings.
- Lighting symbols distinguish general points, wall lights, emergency and exit fittings.
- Distribution symbols show the origin, consumer unit, protective devices and isolators.
- A drawing's legend always takes precedence where a symbol is ambiguous.
Accessory and socket symbols
Socket outlets are shown as a semicircle with lines; the number of lines or added marks indicates single, double or switched variants. Fused connection units, switched fused spurs and cooker outlets each have their own recognised marks.
On a layout, these tell the installer where each accessory goes and what type it is, before any wiring is drawn.
Lighting and switching
Lighting points are typically a circle with cross-lines, with variations for wall lights, spotlights, and emergency or exit luminaires. Switches are shown with their own symbols, distinguishing one-way, two-way and intermediate switching.
Reading these together lets you see which switch controls which point and how the switching is arranged.
The legend wins
If a symbol on a drawing doesn't match the standard, the drawing's own legend is authoritative — always check it first.
Protective devices and distribution
Distribution symbols cover the supply origin, the consumer unit or distribution board, and the protective devices within it — MCBs, RCBOs, RCDs and isolators each have a recognised representation.
On a schematic these show how the installation is protected and divided, from the intake through to the final circuits.
Using symbols on site
In practice, symbols let you take off quantities, plan runs and understand an existing design at a glance. When producing your own drawings, stick to the standard symbols and include a legend so anyone can read them.
Consistency is the point — a layout is only useful if the next person reads it the same way you drew it.
Frequently asked questions
Which standard covers electrical symbols?
UK drawings use BS EN 60617 for graphical symbols, with the older BS 3939 still referenced. Installation layout symbols follow recognised conventions, and any drawing should carry its own legend.
How is a double socket shown?
As the socket-outlet symbol (a semicircle with a line) marked to indicate two outlets — typically with an extra line or a '2'. The drawing's legend confirms the exact convention used.
What if a symbol isn't standard?
Refer to the drawing's legend, which is authoritative for that drawing. If there's no legend and the symbol is unclear, query it rather than assuming.
From guidance to action
Related guides
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Current and pre-2006 UK wiring colours, three-phase identification and marking mixed installations.
Ring vs Radial Circuits
How ring and radial final circuits differ, their cable and protection rules, and when to use each.
Consumer Unit Upgrades Explained
What a consumer unit change involves — assessing the existing installation, RCBO boards and paperwork.
