Consumer Unit (1) – Also commonly known as fuse board/box, this is where the circuits in an installation originate from and where your’ protective devices will be located.

Fixed Current using equipment – A piece of equipment that is a permanent part of an electrical installation, an example would be a cooker that has been hardwired directly.

Fused connection unit (2) – A fused connection unit is a type of accessory which protects a piece of fixed current using equipment.

Accessory – This is something that makes up part of a circuit, but isn’t a fixed current using piece of equipment, an example is a socket.  

Appliance – This is any item of equipment that uses electrical current, the exceptions to this are standalone electrical motors i.e. those that aren’t part of a piece of equipment such as the motor in an extractor fan, and luminaires.

Barrier (3) – Something to prevent contact with a live electrical part, for example a busbar cover within a Consumer unit.

Basic protection – This protects you from electric shock under fault free conditions i.e. in normal use.

Busbar – A solid strip of conducting material, usually copper, to which electrical equipment can be attached and powered. In a domestic setting these can be found inside the consumer unit, normally covered by a busbar cover to prevent someone coming into contact with it while energised.

Cut-out – this is the colloquial name for the Supply Protective Device. The Supply Protective Device is a large fuse based at the origin of your installation, generally in a domestic property they are rated at 60A, 80A or 100A. They are the property of the DNO (Distribution Network Operator) and not to be touched by anyone other than them, unless they have given their express permission.

Circuit – A circuit is an assembly of electrical equipment that originates at the same point and is protected by the same device.

Final Circuit  – The circuit that is supplying power to appliances via a socket, power to a fixed piece of current using equipment such as a cooker, or power to a lighting circuit. This is called a final circuit because it is the final part of the system.

Distribution Circuit – A circuit that provides power to a distribution board.

Radial Circuit – A circuit that has one set of conductors leaving a distribution board and terminating at the furthest point, an example would be a dedicated circuit supplying power to a cooker.

Ring Circuit– A circuit that has two sets of conductors leaving a distribution board from the same point essentially forming a ring, generally only used for socket circuits.

Double insulation – As well as providing basic insulation, double insulation provides an extra layer of insulation.

Earth fault loop path – This is the path the electricity flows when a fault arises causing the activation of the protective device for the circuit affected, starting at the point of the fault:

1. The circuit protective conductor,
2. The main earthing terminal and earthing conductor,
3. For TN systems either the lead sheath of the cable (TN-S) or the combined neutral and earth cable (TN-C-S),
4. For TT systems the earth electrode (not pictured),
5. The path through the earthed neutral point of the substations transformer
6. The transformers winding,
7. The line conductor from the transformer winding back to the point of origin of the fault (not pictured)

Electrical equipment – When using the phrase ‘electrical equipment’ this can refer to any item that is part of the electrical system, such as fuses, generators, transformers etc.

Electrical installation – An electrical installation is an installation made up of electrical equipment having a specific purpose.

Enclosure – This is what surrounds a piece of equipment to provide protection from different types of external influences.

Exposed conductive part – Part of a piece of equipment that can be touched. During normal service this piece of equipment should be safe to touch but it has the potential to become live under fault.

Extraneous conductive part – A part that is not part of the electrical installation and that could introduce a path to earth for the electricity to flow in the event of a fault.

Ferrule – Also known as an electrical crimp, this is a small metal tube that is placed over the stripped end of a multi strand wire and then crushed using a crimping tool to protect the end of the cable. They come in a variety of different types suitable for use in different applications.

Functional switching – The action of operating a device to either vary, or switch on and off the electricity supply to a device.

Insulation – Insulation is the material surrounding a conductor.

Isolator – This is a device that is mechanically operated and is capable of isolating a particular circuit/piece of equipment as required.

Line conductor – What a lot of people mistakenly refer to as the ‘live’ conductor. In a new installation this will be brown in colour and  in older installations it will be red.

Luminaire – This is the term for a light fixture.

Lamp – What is often referred to as a ‘bulb’ a lamp is the part of a light fitting which emits the light.

Main switch – This will be at the origin of the installation generally inside the consumer unit. When it is switched ‘off’ the consumer unit and all associated circuits will be de-energised.

Meter tails – These are split into two parts, the meter tails from the service head to the electricity meter, and the meter tails from the meter to the consumer unit.

Neutral conductor – The other ‘live’ conductor in a circuit. In older installations this will be black and in newer installations this will be blue.

Origin of an installation – This is where the electricity is distributed to an electrical installation, in a house this would be the primary consumer unit.

Plug – A piece of equipment designed to fit inside a socket as means of connecting an appliance or piece of equipment.

Point – This is the part of a circuit that is intended to have current using equipment attached.

Protective conductor (cpc) – A conductor used to provide protection against electric shock, often referred to as the ‘earth’ conductor. In a circuit, it is known as the CPC. CPC stands for Circuit Protective Conductor.

Service cable – This is the cable that supplies electricity into a property, it is terminated in the service head.

Service head – This is where the service cable is terminated and the cut out fuse located

Spur – A spur is a branch off of a ring or a radial circuit.

Socket outlet – Designed to work with a plug to allow the connection of electrical appliances.

Tinned– This refers to the practice of soldering the end of a multi strand cable. This is the method that was used prior to the use of the ferrules for the same purpose. It is no longer allowed in new electrical installations but may still be encountered.

Cable management system – A means of supporting and managing cables in an installation.

Examples include:

• Cable tray (1) – Long, formed sections of material usually metal and usually perforated to allow heat to escape, they are open and the cable sits on top of them.
• Cable ladder – Similar in use to cable tray but constructed differently, resembles a ladder in form, hence the common name. Generally ladder houses larger cables,
• Cable conduit (2) – Generally round in section, essentially a length of tube, can come in a variety of materials and sizes, cables are drawn inside it.
• Cable trunking (3) – Usually rectangular in section with one side being entirely removable, can come in a variety of materials and sizes.