PAT Testing and In-service inspection and testing of electrical equipment (ISITEE) – Is it only for office equipment?
From Simple Visual Inspections to Modern Electrical Safety Management
“PAT Testing (Portable Appliance Testing) has become a familiar term throughout UK workplaces, schools, hospitals, construction sites and public buildings.
For many years, coloured labels and annual testing schedules became synonymous with electrical safety management. However, the history of PAT testing is far more interesting than many realise, reflecting the UK’s evolving approach to electrical safety and risk management.
This article explores how PAT testing developed, why it became so widespread, and how modern guidance has changed the way organisations manage electrical equipment safety.
The Early Days of Workplace Electrical Safety
The origins of PAT testing can be traced back to the rapid growth of electrical equipment during the mid-twentieth century.
By the late 1950s and into the 1960s, workplaces increasingly relied upon portable electrical appliances such as kettles, heaters, drills, typewriters and office equipment.
While these appliances improved productivity, they also introduced new hazards. Damaged cables, faulty plugs, deteriorated insulation and inadequate earthing arrangements led to electric shocks, burns and electrical fires.
At the time, there was no formalised system of routine appliance testing. Instead, safety relied largely on maintenance personnel identifying defects through observation or following an incident.
The Electricity at Work Regulations 1989
A major milestone occurred with the introduction of the Electricity at Work Regulations (EAWR) in 1989. These regulations placed a legal duty on employers, employees and duty holders to ensure that electrical systems were maintained so as to prevent danger.
Regulation 4(2) specifically states:
“As may be necessary to prevent danger, all systems shall be maintained so as to prevent, so far as is reasonably practicable, such danger.”
Although the regulations did not specifically mention “PAT testing” (or even any other specific testing that could be associated with this responsibility, including periodic inspection and testing of electrical installations) many organisations, including the Health & Safety Executive (HSE) and local authorities interpreted them as requiring regular inspection and testing of portable appliances.
This marked the beginning of PAT testing becoming an established part of workplace safety management.
The Rise of Portable Appliance Testing
During the 1990s, specialist PAT testers became increasingly available. These test instruments allowed users to carry out a range of electrical safety tests, including:
- earth continuity testing;
- insulation resistance testing;
- polarity verification;
- earth leakage measurements; and
- functional checks, including load tests
Since then, as testing equipment has become more affordable and certainly more accessible and user-friendly (many types of modern test equipment has guided testing functions that carry out the appropriate tests automatically with in-built test parameters allowing visual indication of PASS and FAIL results), organisations began implementing routine PAT programmes across their premises.
By the late 1990s and into the 2000s, annual PAT testing had become common practice and many businesses adopted blanket testing schedules, often re-testing every appliance every year regardless of its type, condition or environment, though more on this topic later!
The familiar green-coloured PAT label has become a standard sight on workplace equipment throughout the UK.
The Publication of the IEE/IET Code of Practice for In-service Inspection and Testing of Electrical Equipment (ISITEE)
A significant development came with the First Edition of this Code of Practice by the Institution of Electrical Engineers (IEE) in 1994.
The code provided guidance on:
- Inspection procedures
- Test methods
- Equipment classification
- Recommended testing frequencies
- Competency requirements
For the first time, organisations had a recognised framework for managing portable appliance safety.
The publication also helped standardise inspection and testing practices across industries and remains the foundation of modern appliance testing guidance today, currently in its 2020 fifth edition and published by the Institution of Engineering and Technology (IET).
This publication also formally incorporated the term ‘In-service inspection and testing of electrical equipment’ (ISITEE) into the electrical industry, identifying that electrical equipment isn’t only portable-based, typically using a plug and socket-outlet connection, e.g. kettles and toasters.
Now, of course, if an individual is performing inspection and testing on a item of electrical equipment which is in fact ‘portable,’ then they are carrying out ‘PAT testing.’ However, the term ‘In-service inspection and testing of electrical equipment’ (ISITEE) is a cover-all term for the entirety of the process across many items.
However, alongside this portable equipment out in the wilds of the electrical industry, there is also:
- Transportable / moveable equipment
Air compressors and similar that may not necessarily be heavy, but may be bulky and therefore have wheels or castors to assist in transport and movement.
- Hand-held equipment
Electric hand-drill, hair-dryer, and the like which are held in the hand during use and create a large amount of risk if something goes wrong!
- Stationary equipment
Vending machines and washing machines, which are likely to stay in the same place after installation and can be relatively heavy to move.
- Fixed equipment
Hand-dryers and air-conditioning units, which are fixed to a support and are hard-wired into the electrical installation by a fuse-spur or similar.
- Information Technology (IT) equipment
Desktop computers, laptops, printers, and scanners, which are by-nature sensitive to electrical testing and must be treated with care.
- Built-in appliances
Built-in electrical cookers and freezers, where they are built into a prepared recess, where the sides of the recess (e.g. a cupboard) provide the enclosure of the equipment.
The Code of Practice also emphasised that this inspection and testing is not only expected within the offices where this all started, but across workplaces and environments of all sectors utilising electrical equipment, including hotels, schools, universities, hospitals (though may be undertaken by specialist organisations that supply the medical equipment), theatres, museums, general industrial, construction sites, portable buildings, caravan sites and caravans, swimming pools and agricultural and horticultural premises.
The Prevailing Myth of Annual Testing
One of the most persistent misconceptions in electrical safety is that testing must be carried out every year.
In reality, no legislation has ever required annual testing of all portable, or even other types of electrical appliances.
The widespread adoption of annual testing arose from a cautious (mis?-)interpretation of safety requirements rather than any specific statement or legal obligation.
Research conducted by the Health and Safety Executive (HSE) demonstrated that many appliances presented very low levels of risk, particularly:
- Desktop computers
- Computer monitors
- Printers and photocopiers
- Fax machines (remember them?)
- Equipment used in typical, clean office environments
This led regulators and authorities to encourage a more proportionate approach to electrical safety management.
HSE Guidance and Risk-Based Inspection
During the 2000s, the HSE increasingly promoted risk-based inspection and testing. Their own published guidance documents emphasised that:
- Visual inspections often identify the majority of defects.
- Testing frequencies should reflect actual risk.
- Equipment condition is more important than arbitrary testing intervals.
- Low-risk equipment may require little or no routine electrical testing.
The HSE’s message was clear: inspection and testing of electrical equipment should be part of a wider maintenance strategy and not a simple box-ticking exercise.
For reference, PDF downloads freely available from the HSE include ‘maintaining portable electrical equipment’ HSG107.
Modern In-service inspection and Testing
Today, this inspection and testing remain an important tool for electrical safety, but its application has evolved considerably.
The present-day management focuses on:
- Risk-based assessment
- Visual Inspection
- The involvement of Competent Persons
- Record Keeping
The Future of Inspection and Testing
The nature of workplace equipment is changing rapidly. Many modern devices:
- Operate from low-voltage power supplies.
- Use sealed switch-mode power units.
- Incorporate advanced internal protection systems.
- Contain rechargeable batteries rather than direct mains supplies.
At the same time, organisations are increasingly adopting risk-based maintenance strategies supported by asset management software and digital compliance systems.
As a result, the future is likely to involve:
- Greater reliance on visual inspections.
- More targeted testing programmes.
- Enhanced digital record management.
- Risk-based decision making rather than fixed testing intervals.
In conclusion
PAT testing has evolved significantly since its emergence during the late twentieth century. While it was never specifically mandated by legislation, it became a widely accepted method of demonstrating compliance with electrical safety, including duties expected and obligations under the Electricity at Work Regulations 1989.
The industry’s understanding of risk has matured over time. Today’s best practice recognises that effective electrical safety management is not simply about applying a sticker to an appliance once a year.
Instead, it requires a balanced approach that combines visual inspection, appropriate testing, competent personnel and risk-based decision making. More than three decades after the introduction of the Electricity at Work Regulations 1989, In-service inspection and testing continues to play an important role in protecting people from electrical hazards, while adapting to meet the changing demands of modern workplaces and environments.
