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Sparky Speak Definitions

Sometimes when dealing with contractors it is difficult to keep up with the language they use in describing the work they are undertaking for you.  Below is a list of common terms used in electrical installation work with a brief explanation of what it is to guide you:

AC Alternating Current
ADOS Automatic Disconnection of Supply
Amp Unit of electric current
Band I Circuit Any circuit which runs at less than 50v
Band II Circuit Any wiring that carries mains voltage 
Belling Out Slang for testing installations
BS7671 The wiring regulations which is the standard that electrical installations must adhere to 
BESA Box A conduit fitting box
Cartridge Fuse A fuse inside a ceramic tube
Clicks A connection unit usually used in a lighting installation
Class I Equipment Equipment that runs on mains electricity and requires an earth
Class II Equipment Equipment that runs on mains electricity and does not require an earth
Conduit A form of mechanical protection for the installation of cables which can be either PVC or Steel
Consumer Unit Might also be referred to as a Distribution Board, Board, Wylex Unit, Fuse Board, Mains, Mains Board, Consumer Box, Split Load Board or 17th Edition Board
CPC Circuit Protective Conductor i.e. earth conductor
CSA Cross Sectional Area usually of a cable
CTs Current Transformers
Current A measure of electricity flowing in a circuit
DC Direct Current
Earth Fault Loop Impedence Impedence of the live circuit from a house back to the sub station which proves that the resistance is low enough to disrupt the protective device for that particular circuit within the time prescribed in the wiring regulations 
Earth Electrode Usually a Rod but not always - driven into the ground to earth a property.  Used in TT earthing systems
Earth Fault A short circuit between the Live and the Earth
Earthing System Description of the type of earthing system in use
Electrical Installation Certificate (EIC) Used for the installation of a new circuit that records the results of tests that must be undertaken to prove the system is safe to be energised.  Once the system is energised, it then records all of the live test results. 
Exposed Conductive Part A metal part which can be touched and is not normally live but could become so when basic insulation fails
Extra Low Voltage A voltage not exceeding 50Volts
Extraneous Conductive Part A metal part which could under fault conditions introduce a voltage into a property
Fast Fix Box A socket or switch box usually installed after plastering has taken place
Fault Current A current which makes your protective device operate
Fault Protection A system put in place to prevent persons receiving a shock under fault conditions
Impedence Opposition to current flow
Insulation Resistance A test on the system to ensure the system is satisfactory for energisation
IP Rating A rating given to an item for differing degrees of ingress i.e. solids, moisture or water.  Most typically quoted for products being used outside or in bathrooms
LABC Local Authority Building Control
Line Conductor  Usually the live conductor
Main Protective Bonding Conductor A conductor installed from the Mains earth terminal to all extraneous conductive parts
MET Main Earthing Terminal
MCB Miniature Circuit Breaker
Megger Refers to a brand of testing equipment
Minor Works Certificate Used for an addition to an existing circuit that records the results of tests that must be undertaken to prove the system is safe to be energised.  Once the system is energised, it then records all of the live test results.
OHM Unit of electrical impedence or resistance
OSG On Site Guide which provides contractors general guidance as to how to meet the requirements of the regulations
Overload Current An over current in a healthy circuit eg too many items plugged in to a kitchen ring and the MCB keeps tripping
PIR Periodic Inspection Report is an electrical report on an existing installation
PME Protective Multiple Earthing
Polarity Testing To prove a fuse or switch is fitted in the line conductor
Prospective Fault Current A measurement to simulate the largest fault current which would flow in the event of a short circuit
Pyro Slang for mineral insulated cable
Resistance The opposition to current flow
Rewirable Fuse A fuse wire in a fuse carrier that is open to inspection.  Officially BS3036
RCD A unit that monitors current flow in a circuit and will trip if it detects a small leakage to Earth
Safe Zone A zone within a wall where buried cables can be safely installed
Short Circuit A fault occuring between Line and Neutral
Spur An extension to a ring or radial circuit
Tube Slang for Conduit of any type
Volt\Voltage Unit of electricity rating usually 230Volts for UK domestic circumstances
Watt Unit of electric power
Ze Earth fault loop impedance at the origin of supply
Zs Earth fault loop impedance at the end of a circuit including the Ze value