BS7671 British Standard covering the Wiring Regulations for Electrical Installations. The working document for electricians to ensure the Electricity at Work Regulations.

Circuit Design Before an electrician selects the correct cable and MCB for a circuit, the circuit is designed to ensure it's safe operation. Consideration is made for the type of circuit, the load on the circuit, whether the cable passes through building insulation and other additional factors.

Consumer Unit The part of the fixed electrical installations that contains the circuit protective devices, either fuses, MCBs or RCDs. The consumer unit is where circuits can be isolated if necessary by switching off the MCB or removing the fuse for a circuit.

Equipotential Bonding The electrical connection between earth and exposed conductive parts and other conductors in the property eg gas, water, oil pipes.

Earthing If an electrical fault occurs between a live conductor and earth, the protective conductor (earthing) must ideally allow a very large current to flow. This enables the protective devices, MCB and/or RCBO to operate virtually instantly.

Electrical Fault An electrical fault occurs when current flows through an abnormal or unintended path. The may be a result in the failure of insulation or a fault in the installation. This can be between either the live and neutral conductors, or the live and earth. An electrical fault can result in a large fault current.

Feed in Tariffs (FITs) The government deal with energy suppliers whereby you are paid for the electricity you generate from a renewable source. Once registered, your supplier will pay you a set rate for every kWh of electricity you produce. The current rate is 41.3pence per kWh generated, guaranteed for 25 years, tax free and rise in line with the Retail Price Index. The starting rate will decrease from 1 April 2012. Further, any energy that is not used is sold back to the National Grid at 3 pence per kWh. Full information can be found at the Feed in Tariffs website.

Kilowatt hour (kWh) is 1000 watts of energy used for one hour. For example, a 100 watt lightbulb switched on for 10 hours equals 1kWh.

Kilowatt peak (kWp) is the peak power and refers to the maximum energy output achieved by a solar cell under full solar radiation. The actual output power of the cell could be about 25% lower when the cell is installed on a roof.

LED Light Emitting Diode. LEDs are a low energy alternative to standard light bulbs. The latest LED lighting systems provide very bright illumination for very little energy usage.

MCB Mini Circuit Breaker. An MCB is the modern version of a fuse. They are found in the consumer unit of an electrical installation. MCBs are available with different ratings in AMPs, and of different types. Selecting the correct rating and type of MCB for a circuit is an integral part of it's design. Your electrician will ensure the circuit is designed correctly.

Part P The Building Regulations have different 'Parts' governing the requirements of the Regulations. Part P governs the Electrical Safety in Dwellings. Part P registered Electricians are registered with an organisation who require a level of competence for membership. They in turn will offer a guarantee for electrical work carried out under their scheme.

PAT Testing Portable Appliance Testing. Testing of appliances that 'plug into' the electrical system of your property. An appliance is part of the electrical circuit and as such must be free from defect or fault to remain safe. PAT testing is a requirement for appliances in commercial settings. Appliances that are tested are marked with a sticker that show them as safe (or otherwise) and the date that they are due to be retested.

Photovoltaics Uses solar energy from the sun to create electricity via cells containing a photovoltaic material such as silicon.

PIR Passive Infra Red. The detection used in movement sensor switches.

Qualified Electrician Qualifications do not guarantee a good electrician, but they do signify that the electrician or electrical contractor knows correct and safe way to work on an electric installation.

RCD Residual Circuit Breaker. An RCD constantly monitors the current flowing through it. It will automatically disconnects the supply if there is a 'leak to earth'. The RCDs in an up to date installation will disconnect the supply in less than 40 milli seconds if they detect a fault.

Ring Circuit The type of circuit most commonly used for domestic plug sockets.

SELV Safely Extra Low Voltage systems are extra low systems, separated from earth and other electrical systems. SELV circuits are often found in zones 1 & 2 of a bathroom.

Smoke Alarm Smoke and fire alarms are a requirement under Part B of the Building Regulations. The regulations state that smoke alarms should be fitted on each floor, within 3 metres of bedrooms and 7 metres of kitchens.

Special Locations Some locations carry additional risk and require special attention. They are governed by additional requirements within the wiring regulations. Special locations include the rooms containing a bath / shower; rooms containing a sauna; floor and ceiling heating systems.