What needs PAT testing?
For the purpose of legislation, portable appliances include all equipment that is not part of a fixed installation but is meant to be connected to a fixed installation.
Any appliance that uses a flexible cable or plug and socket qualifies as a portable appliance. In other words, if you have an appliance that has a plug that is intended to be connected to a wall socket, it qualifies as needing to be PAT tested.
Examples of appliances that require testing:
Kettle
Toaster
Hi-FI Equipment
Industrial equipment
Fridges
Freezers
Washing Machines
Dish Washers
Lamps
Extension Leads
Power supplies
Computers
Vacuum Cleaners
Power Tools
Soldering Irons
Portable Heaters
Classes of appliance.
Appliances are categorized into different classes based on their construction and electrical features. These classes help determine the type of testing and inspection required to maintain safety standards. Understanding these classes is essential for conducting effective PAT testing and ensuring the well-being of users.
Class I, Earthed exposed metalwork
The most common method of protection against electric shock in electrical installations is a protective measure called Automatic Disconnection of Supply. With this protective measure, the metal casing of the equipment is connected to earth via the protective conductor. Where a fault occurs (for example, a failure of basic insulation caused by heat damage to the insulation of wires in a luminaire), the live conductors make contact with the exposed-conductive-parts, causing a high current to flow to earth. This results in operation of the fuse, circuit-breaker or RCD protecting the circuit, thereby disconnecting the fault and removing the danger. This all happens without any user intervention - hence the term “automatic disconnection of supply”. In a healthy circuit, the voltage on the exposed-conductive-parts should not attain a level where serious injury can occur in the time it takes for the protection to operate. Class I appliances include: Refrigerators, washing machines, dishwashers, some power tools, microwave ovens, electric irons, electric heaters, toasters, kettles, desktop computers and vacuum cleaners.
Class I appliances include:
Refrigerators, washing machines, dishwashers, some power tools, microwave ovens, electric irons, electric heaters, toasters, kettles, desktop computers and vacuum cleaners.
Class II, Double or reinforced insulation.
This protective measure combines basic protection insulation with a separate layer of supplementary insulation, leading to the term “double insulation”. Some products use one layer of special reinforced insulation instead of two separate layers; this is commonly found in power tools. In both cases, fault protection is provided by insulation so there is no requirement for a connection with earth. Many double-insulated products use a plastic enclosure for the supplementary insulation. Some Class II products feature a durable and substantially continuous electrical enclosure of insulating material that envelops all conductive parts, with the exception of small parts such as nameplates, screws and rivets, which are insulated from live parts by insulation.
Class II appliances include:
Televisions, hairdryers, table lamps, audio equipment, some power tools and small kitchen appliances.
Class II FE, Double insulated with functional earth
These appliances fulfil the criteria for a Class II appliance but utilise the functional earth for functional purposes only and not for safety.
Class II FE appliances include:
Laptop and other power supplies.
Class III appliances
Although Class III appliances incorporate insulation over live parts, they are low voltage and generally do not require PAT testing.
Electrical Separation
With this method of fault protection, basic insulation is utilised but the risk of electric shock is mitigated by the supply being electrically separated from other circuits and the mass of earth via an isolating transformer. Therefore, if a user is simultaneously in contact with the mass of earth and a faulty piece of equipment, no electric shock to earth will occur. An example of this type of appliance is a building site transformer.
Electrical separation appliances incluide:
A building site transformer.