Portable appliance testing
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Portable appliance testing (commonly known as "PAT", "PAT Inspection" or "PAT Testing") is a process in the United Kingdom,the Republic of Ireland, New Zealand and Australia by which electrical appliances are routinely checked for safety. The correct term for the whole process is "in-service inspection & testing of electrical equipment".[citation needed]
Similar procedures exist in in other countries, for example, testing of equipment according to BGV A3 in Germany.
Health and safety regulations require that the electrical appliances be safe to prevent harm to the workers. Many types of equipment require testing at regular intervals to ensure continual safety; the interval between tests depending on both the type of appliance and the environment it is used in.
Misleading advice and advertising, often by companies who offer the testing, is contributing to low-risk businesses such as offices, shops and hotels paying unnecessarily for over-the-top maintenance regimes. The law simply requires an employer to ensure that electrical equipment is maintained in order to prevent danger - it does not state that every item has to be tested or how often testing needs to be carried out.
Evidence of testing is clearly visible to workers in the form of "passed", "tested for electrical safety" and "do not use after..." labels affixed to various parts of the electrical equipment used.
Portable appliance testing and inspection was, however, conducted on a 3 month (high risk) and 6 month (low risk) cycle from the early 1960s onwards. This was under the control of DOEPSA—the Department of the Environment Property and Services Agency (circa 1970 to 2000)—prior to that it was known as the Ministry of Public Buildings and Works (MOPBW) until about 1970.[citation needed]
Extensive record keeping was made into log-books and generally the equipment used was an insulation resistance tester, simple hand tools and visual inspection. This testing and inspection was done under a planned maintenance scheme and predated both the Health and Safety at Work Act 1974 and the Electricity at Work Act 1990 that are frequently quoted as the reason that PAT inspection is done.[citation needed]
In reality neither act nor their corresponding regulations detail PAT inspection as an obligation, but rather state a requirement of maintenance of safety and evidence of routine maintenance for all hand-held, portable and plug-in equipment.
Testing equipment specifically designed for PAT inspections was developed using portable devices, which were based on the testing equipment used by manufacturers to ensure compliance with the British Standard Code of Practice relevant to that type of appliance.[citation needed]
One other check carried out on high risk equipment such as hand held electrical drills issued from a government department stores was an earth test, where 25 A was passed down the earth conductor to substantiate that the earth was a sound and valid connection.[citation needed]
Contents
Name
Portable appliance testing is abbreviated as PAT. The phrase "PAT Testing" is in fact a tautology, in the same way that some people say "LCD Display" (see also RAS syndrome and PIN number). However, the phrase is commonly used in the industry even though most people realise it is incorrect. The correct term for the whole process is "In-service Inspection & Testing of Electrical Equipment" (as defined by IET/IEE and City and Guilds).
Legal
Regulations on who must have their equipment PAT tested
British law (the Electricity at Work Regulations 1989 ) requires that all electrical systems (including electrical appliances) are maintained (so far as is reasonably practicable) to prevent danger. A compentent person must inspect the installation regularly in any public building or a place that people work; private houses do not need this test. Guidance from the Institution of Engineering and Technology (IET, published under the IEE brand) and the Health and Safety Executive (HSE) suggest initial intervals for combined inspection and testing that range from three months (for construction equipment) to one year for inspection and, in many cases, longer periods for testing (certain types of appliance in schools, hotels, offices and shops).[1]
The inspection of the appliances can largely be carried out in-house in many organisations. This can result in cost savings and more flexibility when PAT testing is carried out.
The European Low Voltage Directive governs the manufacture or importation of electrical appliances. Compliance to this has to be declared and indicated by the display of the CE mark on the product. The responsibility for this lies with the manufacturer or the importer and is policed by the Trading Standards. However, it is important to have a maintenance regime for electrical appliances. The implementation of this is up to employers. The HSE or the local authority is responsible for the policing of this.
Carrying out PAT testing
This can be done by hiring an external company to test all the electrical products in a business (someone who has had some PAT training, either by an official qualification or by attending a health and safety course offered by some electrical health and safety companies) or it can be done in-house by a competent person. In a low-risk environment most dangerous defects can be found simply by checking the appliances for obvious signs of damage such as frayed cables.
The following steps are taken when an external company is testing a business' electrical equipment.
User checks
Advising the user of potential danger signs can result in problems being picked up before they can result in any danger. For example, if the power cable is frayed or the plug is cracked, users need to be advised not to use the appliance and report the fault to a supervisor. This information can be put across, say by the use of a poster or in a memo. User checks are always carried out before operation, and the results are generally not recorded, unless a defect is identified.
Formal visual inspections
This is a process of simply inspecting the appliance, the cable and the plug for any obvious signs of damage. According to the HSE, this process can find more than 90% of faults.
Combined inspections and PAT testing
At periodic intervals, the portable appliances are tested to measure that the degree of protection to ensure that it is adequate. At these intervals, a formal visual inspection is carried out and then followed by PAT testing. Note the inside of the plug should be checked unless it is moulded or there is an unbroken seal covering the screws (bad internal wiring or an unsuitable fuse would cause the item to be classed as dangerous).
The tests that an individual must carry out to declare an item electrically safe is dependent on the class of construction (shown below). Some of these tests are:
- earth continuity
- insulation resistance
- polarity of wiring
Class of construction
Electrical appliance classes are differentiated by a series of IEC protection classes. The protocols for PAT Testing vary by appliance class.
- Class I – Single insulated wiring, which requires an earth connection. There is no symbol for a Class I product so if a rating plate has no symbol on it then it is usually Class I.
- Class II – Double insulated wiring, therefore no need for a earth lead. Class II is indicated by double box.
- Class III – These are appliances that are supplied at a low voltage (usually called Separated Extra Low Voltage) which must be less than 50 V. These appliances are supplied with a transformer supply that is also marked.
PAT training and qualifications
It is not stated in the health and safety regulations for an individual to have any qualifications to PAT Test but it does state that it must be done by a competent person who has been given instruction to perform the necessary checks in a safe manner. Personnel performing PAT may attend a course for training.
In the UK, there is no requirement to have a formal qualification for persons carrying out PAT Testing. The Electricity at Work regulations of 1989 simply state that inspecting and testing must be carried out by a competent person, however does not mention a benchmark for competency. It has become accepted practice, however, for individuals operating as PAT Testers to hold a 2377–12 City and Guilds qualification. PAT Testers in the UK do not need to be electricians or have a background in the electrical industry. The only U.K. nationally recognized qualification of competence in PAT is offered by City & Guilds: 'Code of Practice for In-service Inspection and Testing of Electrical Equipment – Vocational 3 (No. 2377)'.[2] although many other non-recognized PAT training courses are available.
It is a legal requirement to have attended a course or gained a qualification in order to PAT test in Australia. Proof of a company’s competence in PAT testing is usually found in the form of a course certificate or qualification. A formal examination process for the topic is operated in collaboration with EAL or city and guilds (the awarding body) under the authority of the QCA (The Qualifications and Curriculum Authority) who validate and authorise the qualification.
Types of PAT testers
Pass / fail PAT testers
These are the simple-to-use and comparatively much cheaper portable appliance testers for most businesses who will test in-house to carry out the testing and suitable for a wide range of businesses. They simply say PASS or FAIL when a test is carried out. Mains powered testers require AC power. Battery operated PAT testers are self contained and convenient to use. They usually come with rechargeable batteries.
These testers have a simple "lights" system. They have a "Pass" light, a "Fail" light, options for Class I metal / plastic or Class II. They also will show:
- earth continuity
- insulation resistance
- polarity.
Advanced PAT testers
These testers display more information than just pass or fail, including:
- Earth continuity resistance (aka Earth Bond) tests with a measurement range of 0 – 1.99 Ω at high test currents (usually 8 A, 10 A or 25 A) and lower test currents (in the range 20 mA to 200 mA), enabling a complete range of appliances including personal computers to be tested;
- Insulation resistance tests at test voltages of 500 V DC or 250 V DC.
- Protective conductor/touch current measurement (sometimes referred to as "earth leakage tests" on some older PAT units);
- Fuse test;
- Lead polarity.
These readings require interpretation by an electrician or someone with electrical qualifications. Advanced PAT testers are effective as facilities management tools because of they can record the location and test status of electrical equipment and appliances.
RCD testing
Some units can test Residual-current devices, following the recommendation in the current IEE Code of Practice to test any RCD fitted on an extension lead or multiway adapter.
Computerised PAT testers
Some advanced PAT testers can download information to a computer. Bluetooth enabled computerised PAT testers make the two way transfer of test data between the tester and PC-based record keeping systems much simpler, and can be used with other test accessories such as label printers.
Calibration of PAT testers
As PAT testers are sophisticated instruments, it is important to make sure that they are continuing to measure correctly. If a company fails to check and maintain calibration, it could face difficulty substantiating any measurements in the event of a claim. It is usually recommended that calibration is carried out annually on a PAT testing unit.
When a PAT Tester is calibrated it is re-configuring it to match the original specification. This includes:
- Calibrating the unit back to national standards. This is best performed by the product manufacturer (if they offer a calibration service) or a laboratory accredited by UKAS [3]
- If it is mains powered, then a safety test must be carried out.
- A calibration certificate should be issued to prove the PAT unit has been electrically tested.
Dual purpose checkboxes have also been introduced which are capable of validating the accuracy of both electrical installation testers and portable appliance testers.
See also
References
External links
