Electrician speak, explained
Electricians use a lot of jargon. Here's what the most common terms actually mean — in plain English.
- AC (alternating current)
- Current that reverses direction many times a second. UK mains electricity is AC at 50 hertz.
- Amp (A)
- The unit of electrical current — how much electricity is flowing.
- BS 7671
- The UK standard for electrical installations, also called the IET Wiring Regulations. See our guide.
- Bonding
- Connecting metal pipes and other conductive parts to the main earthing terminal so they stay at the same voltage in a fault.
- Circuit
- A complete path for electricity — for example all the sockets on one breaker.
- Consumer unit (CU)
- The modern name for the fuse box: it holds the main switch, RCDs and circuit breakers. See consumer unit upgrades.
- Conduit and trunking
- Tubes and channels that protect and route cables, often in commercial installations.
- CPC (circuit protective conductor)
- The earth wire in a circuit, which gives fault current a safe path.
- DC (direct current)
- Current that flows in one direction, as produced by batteries and solar panels.
- DNO
- Distribution network operator — the company that owns the cables bringing power to your property. Call 105 for a power cut.
- Double pole (DP) switch
- A switch that disconnects both the line and neutral conductors.
- EICR
- Electrical Installation Condition Report — an inspection of an existing installation. See EICRs.
- Final circuit
- A circuit that supplies equipment directly, such as sockets or lights.
- FCU (fused connection unit)
- A switched or unswitched fused outlet used to connect fixed appliances, often called a fused spur.
- Hertz (Hz)
- Cycles per second. UK mains alternates at 50Hz.
- Insulation resistance (IR)
- A test showing how well cable insulation is stopping current leaking where it shouldn't.
- IP rating
- Ingress protection — a two-digit code showing how well a fitting resists dust and water. Important in bathrooms and outdoors.
- Line (live)
- The conductor that carries current to the load. Brown in modern wiring.
- MCB (miniature circuit breaker)
- A resettable switch that protects a circuit against overload and short circuits.
- Neutral
- The conductor that completes the circuit back to the supply. Blue in modern wiring.
- Ohm (Ω)
- The unit of electrical resistance.
- Overload
- When a circuit carries more current than it's designed for over time, causing heat.
- PIR sensor
- Passive infrared sensor that detects movement — used in security lighting.
- Radial circuit
- A circuit that runs out from the consumer unit and ends at the last point.
- RCD (residual current device)
- A life-saving device that switches off the power if it detects current leaking to earth.
- RCBO
- A combined RCD and MCB protecting a single circuit, so a fault on one circuit doesn't switch off others.
- Ring final circuit
- A socket circuit that loops from the consumer unit and back again — common in UK homes.
- Short circuit
- An unintended low-resistance connection causing a very high current, which the protective device should cut off.
- Spur
- A branch taken off an existing circuit to supply an extra point.
- SPD (surge protective device)
- A device that protects your installation from voltage spikes.
- SWA cable
- Steel wire armoured cable, used for underground and outdoor runs, for example to garages and garden rooms.
- Volt (V)
- The unit of electrical pressure. UK mains is nominally 230V.
- Watt (W)
- The unit of power — volts multiplied by amps.
Still not sure what something means?
Call us — we're always happy to explain things in plain English, with no obligation.