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PAT Testing Definitions

Ever been mystified by what people are talking about when they reference PAT testing? Don’t know your appliances from your classes? Just want more information on what it all means?

Our comprehensive list of PAT testing definitions should hopefully shed some light on what you need to know about PAT testing.

Accessory – Defined as a device that is ‘other than current-using equipment’, an accessory is generally associated as being an item that can associated with equipment that does use current, or the wiring of an installation.

Appliance – Any item that uses current that is not a luminaire or an independent motor. Appliances are further broken down into different categories and classes in order to understand the exact requirements of what form of test the appliance must be subjected to. Such examples include portable appliances, which are deemed as being equipment that uses electricity and is less than 18Kg in weight.

Appliances or Equipment for Building In – This generally refers to those appliances that tend to be placed under cupboards, in recesses or other similar niches.  The IET says that ‘in general, equipment for building-in does not have an enclosure on all sides’.

Basic Insulation – This refers to the insulation that is applied to live parts. It’s a fundamental aspect of most wiring and appliances in order to prevent electrical shocks. Breakdowns of electrical insulation can be flagged up by PAT testing, allowing organisations to act before the appliance in question becomes a serious danger.

Circuit Protective Conductor – Also known as CPC, this is a protective conductor that connects together a main earthing terminal to exposed-conductive parts of equipment.  In simple terms, this means that an area of an appliance that carries electricity that can be touched. It shouldn’t be live, but can come live under fault conditions.  It also known as an earth conductor, or an earth wire.

Class 0 Equipment – This type of equipment relies on simple basic insulation. This means that essential there is no extra insulation against electrical shock, meaning that if the insulation fails this type of equipment is reliant on the environment around it to remain safe.

Class I Equipment – These types of equipment do not just rely on basic insulation, but also have connections to a protective conductor for additional safety.

Class II Equipment – Equipment under this category usually have two or more forms of insulation. Class II equipment is generally things such as power drills that are used frequently and must have higher levels of protection.

Class III Equipment – Equipment that works on SELV supply means that it works on a lower voltage.  This means there is less chance of electrical shock when using the appliance.

Cord Set – A lead with a plug or connector that can be used to connect something to an electrical supply.

Competent Person – Every organisation should appoint a competent person who will be responsible for the day to day electrical safety and can –optionally – carry out things such as PAT testing.

They should have:

  • Understand the principles of electricity
  • Understanding of the particular appliance, and the work that must be done
  • Understand electrical hazards
  • The ability to decide whether it is safe for something to be used or not.

Current-Using Equipment – Many types of appliance take the current flowing through them and output it as something else. Such an example would be a light, which transforms electrical energy directly into light.

Danger – We shouldn’t have to define this one really, but electrical dangers are extremely high, and it is important that employees are given adequate training on electrical safety.

Direct Contact – Refers to the touching of live electrical parts, which shouldn’t be done in any circumstances.

Double Insulated – Refers to appliances or wiring that has double the insulative properties rather than just basic insulation.

Earth – The reference point in an electrical circuit to form a direct physical connection to the earth.

Electric Shock – The passing of an electrical current through the human body. Can be fatal, and steps must be taken to avoid this at all costs.

Electrical equipment – Refers to absolutely everything that uses electricity to operate. From household appliances to hand-held tools, all of them are electrical equipment.

Electrical Installation – Incorporating a wiring system within an area with the aim of supplying electricity easily from a selection of outlets.

Enclosure – Essentially refers to the protection of equipment against stuff from the outside, usually be means of casing.

Exposed-Conductive-Part – Technically an exposed part of an appliance, it should be able to be safely touched apart from under fault conditions where it will carry a current.

Fault – This refers to a circuit behaving in a way it shouldn’t, essentially meaning the current flowing through the circuit isn’t moving along its intended path but is instead flowing in a way that wasn’t intended.

Fault Protection – Simply refers to the protection under fault conditions

Fixed equipment – Secured in place constantly, this type of equipment is not eligible for a PAT test.

Flexible Cable – A cable that can bend easily even while in use. Most common appliance cables are like this.

Fuse – A device built into circuits that melts when currents stronger than the fuse allows flow through the circuit. This breaks the circuit and gives the current nowhere to flow. It’s an essential safety tool.

Hand-Held Appliance/Equipment – Defined as ‘high risk’ equipment, hand-held devices must be subjected to more regular testing than other appliances because they’re much more likely to be damaged.

Indirect contact – Electricity arcing out from a previously safe conductive area under fault conditions can cause indirect contact with electricity.

IT equipment – when PAT testing, several rules must be observed when carrying out the test on IT equipment. Generally, lower power must be used to ensure that the delicate internal components of the equipment aren’t damaged.

Instructed Person – Anyone within an organisation who has been advised on the dangers of electricity and how to avoid them.

Insulation – A material that is non-conductive and surrounds a conductor to ensure that dangerous electricity doesn’t leak out.

Isolation – A failsafe to make sure an area of an installation can be shut off in a hurry.

Leakage current – Current that leaks is wandering away from the conductive path it is meant to travel along.

Live part – Should not be touched under any circumstances unless an appliance is off. These are usually kept inside an appliance and should not be exposed.

Movable Equipment – Should be up 18kg in weight and is easily movable. They also often have wheels or castors to move them around.

PAT – Portable Appliance Testing. Refers to the process of testing all portable appliances within an environment to check they are 100% safe for humans to use.

PAT instrument – A device used to gain the reading necessary to adhere to the regulations for safety in a working environment.

Portable Appliances – Less than 18kg in mass and intended to be moved while in operation. Examples include kettles, toasters, vacuum cleaners and potentially any other item that can connect to a source of electricity such as a mains outlet.

Protective Conductor – Ensures protection against electric shock should an appliance become live and is used for connecting exposed metalwork to ground.

Reinforced insulation – Still refers to the single insulation, but the insulation found is built up of layers to provide reinforced or double insulation.

RCD (Residual Current Device) – Forces a circuit to trip out when dangerous electrical instances occur, preventing the likelihood of electrical shock.

SELV (Separated Extra Low Voltage) – Refers to systems that run on lower voltages and reduce the risk of electric shock.

Skilled Person – The person with sufficient technical knowledge to avoid the dangers of electricity.

Socket-outlet –  Any fixed installation that is intended to receive a plug.

Stationary Equipment/Appliances – Usually fixed in place with a mass of over 18KG. Usually still eligible for PAT testing.

Written by Barry Atkins