Sockets, Plugs, Switches (wiring devices)
Accessory
The user-facing parts of an electrical installation — wall sockets, plugs, light switches, and dimmers. They connect appliances to mains power safely and let users control circuits manually.
What it looks like
Sockets, Plugs, Switches (wiring devices)
A typical accessory — exact shape, colour and markings vary between manufacturers.
Types & variants
Key specs
Rated current
A13A UK, 16A EU Schuko, 15A US NEMA. Don't exceed.
Voltage rating
V230V UK/EU/India, 120V US/Canada, 240V Australia.
IP rating
—IP2X (finger-safe) minimum indoor. IP54+ for outdoor / wet.
Switch type
—1-gang, 2-gang; 1-way or 2-way; rocker, toggle, touch.
Child protection
—Shuttered sockets (UK mandatory) prevent object insertion.
Markings
Rated current + voltage stamped on front (e.g. 13A 250V~). Approval marks (BSI, CE, UL, ISI). Terminal markings: L (line), N (neutral), E (earth).
Standard values
UK: 13A switched socket. EU: 16A Schuko. US: 15A NEMA 5-15R. Box depth: 25mm shallow, 35mm deep, 47mm for smart sockets. Cable sizes: 1.0mm² lighting, 2.5mm² sockets.
How to choose
1) Match to your country's plug standard. 2) Pick current rating ≥ circuit breaker. 3) Use shuttered sockets where children are present. 4) For outdoor, use IP54+ with weatherproof lid. 5) For LED dimming, use trailing-edge dimmer. 6) Match box depth to cable count. 7) Always install by a licensed electrician.
Pinout & package
Wall-mounted in a flush or surface back box. Terminals: L (line/brown/red), N (neutral/blue/black), E (earth/green-yellow). Switches break only the line. USB sockets add L/N terminals for internal power supply.
Example circuits
- Standard 13A double socket on a ring final circuit
- Two-way stair light switching (two SPDT switches)
- Intermediate switch in a 3-point stairwell lighting circuit
- Dimmer switch controlling LED downlights
- Weatherproof outdoor socket on a dedicated RCBO circuit
Common failures
Loose terminal screws cause overheating and melted sockets (most common failure). Arcing damages contact faces. Shutter mechanism jams. Smart switches lose Wi-Fi pairing. USB ports fail from capacitor aging.
How to test
POWER OFF. Check terminals are tight (screw torque typically 1.5–2.5Nm). Insulation resistance L-N, L-E, N-E (≥1MΩ). Powered: voltage between L-N should be nominal (230V ±10%). Socket tester confirms L/N/E wiring and detects faults like missing earth.
Substitutes
Hard-wired connection (no plug) for fixed appliances. Smart relay hidden in wall box for app-controlled switching of conventional sockets.