PAT Testing in Offices

Electrical appliances start off perfectly safe, but with use can deteriorate to an extent where there is a risk of an electric shock or a fire. Just as regular MOT checks ensure the safety of cars on the road, Portable Appliance Testing (or PAT to use the popular acronym) ensures that electrical appliances continue to be safe to use.

At first sight, PAT Testing looks quite technical and expensive, and as a result many companies either contract out this aspect of Health & Safety or ignore it altogether. However, a proper understanding of the requirements can lead to a safer workplace.

If testing is carried out “in-house”, a substantial saving in cost can be realised. This article aims to provide the reader with an understanding of PAT Testing and the background to it.


Portable appliance testing, or PAT Testing seems to have an aura of the “black arts” about it. As a result a lot of companies either ignore it altogether or sub-contract this aspect of Health & Safety implementation. However, a proper understanding of the requirements can lead to a safer workplace, and if in-house testing is carried out a substantial saving in cost. This article aims to provide the reader with a full understanding of PAT Testing and the background to it.

Design of electrical appliances

If appliances that use mains electricity should develop a fault the consequences to the user can be lethal. In the design of electrical appliances steps are taken to prevent this. It is always possible for appliances to become faulty. However, the design precautions taken are such that a single fault will not result in any danger to the user.

On appliances that have large areas of exposed metal, say a PC or an electric fire, this metal is connected to the Earth pin of the mains plug. The idea is that if high voltages should develop within the PC due to a single fault, this cannot reach the user, as the whole unit is enclosed in a “safe” earthed case. This type of protections is known as Class I.

The other way of providing protection is by the use of two separate layers of insulation. If a single fault resulted in the first layer of insulation being breached, then the second layer of protection is still available. This method is used in handheld appliances such as drills and hair dryers and is generally know as Class II.

Class II appliances are inherently safe and require less frequent testing. They are always indicated by the “double box” symbol.

PAT Testing Regulations

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, like cars, it is important to have a maintenance regime for electrical appliances. The Electricity at Work Regulations (1989) requires that electrical appliances be maintained so that they remain safe during use. The implementation of this is up to employers. The HSE or the local authority is responsible for the policing of this.

Planning your PAT Testing

The first step is to make an inventory of all the electrical appliances. For every item, one needs to work out the frequency of the maintenance checks, based on the method of protection (i.e. Class I or II), the degree of portability and the environment it is used in.

For example appliances that are handheld whilst in use, such as hair-dryers need to be inspected more frequently than a PC monitor that is moved rarely. An electric fire in a factory needs to be inspected more frequently than one used in an office.

It is essential to prepare a Test Record for each appliance. As the maintenance program is carried out, results and comments can be recorded here. This can be invaluable evidence if there is an incident concerning an appliance and a compensation claim is made.

On completing the maintenance, the appliance has to be labelled. This has to indicate the date that testing has taken place and the date after which the appliance should not be used. Equipment that fails should be removed from use and marked appropriately.


Having looked at the regulations and spent some time planning, we need to develop a method of maintaining the appliances. The Health & Safety Executive (HSE) recommends three levels of maintenance actions.

User checks

Users need to be encouraged to look critically for signs of possible hazard every time they use electrical equipment. This can be done easily by making everyone aware of what is considered to be bad practice. A poster is one way of doing this. It is also good practice to introduce this as part of the induction process for new staff or at regular staff meetings.

Formal Visual Inspections

This is carried out at pre-determined intervals. It is quite straightforward and consists of visually inspecting the power cable, appliance and plug for any obvious problems and the results recorded. At this stage, it is important to open the plug and check that the wiring is sound. According to the HSE, this stage can result in more than 90% of potential problems being spotted. Some examples of faults that may be observed are shown below.

Combined Inspection and PAT Testing

This again is carried out at pre-determined intervals. For the checking of electrical safety, one will require a PAT Tester. There are many PAT Testers available but the ones with pass/fail indications are quite easy to use. All one has to do is plug the appliance into the tester, connect a test lead and press a button. The tester will carry out the required tests and indicate whether the appliance is safe or not.

In addition to the scheduled periods, testing needs to be carried out if there is reason to suspect that equipment may be faulty, and after repairs or any modification has been carried out.

PAT Testing in-house: Cost savings

If an establishment had 400 electrical items, this would result in an annual cost of about £1000 if this were to be contracted out. However, purchasing a PAT Tester for about £200 and having a firm understanding of the requirements, a comprehensive in-house safety strategy can be put in place. This will result in immediate savings. The option of renting a suitable PAT Tester costing about £75 a month, allows further cost savings.