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In-Service Inspection and Testing (Pat Testing) an explanation

The technical term for PAT Testing (Portable Appliance Testing) is ‘In-Service Inspection and Testing’.

This process is technically the testing procedure that governs over PAT testing, but it also expands upon the basic PAT testing procedures by adding in more detail and making sure users perform electrical tests as well.

To help you understand better, In-Service Inspection and Testing is generally broken down into three specific categories:

  • User Checks
  • Formal Visual Inspections
  • Combined Inspection and Testing

These are generally vastly different procedures, and it is important when considering electrical safety in the workplace to make sure you are constantly aware of what each one means, and how it affects your organisation.

Here’s a breakdown of what exactly each one means, and how it affects you.

User Checks

Within a workplace environment anybody who is using an appliance should be instructed on the procedure for critically looking at appliances, thus raising their awareness of potential dangers to do with using that appliance.

The user is, after all, the best person to report a fault with an appliance, as they are the person who interacts with it the most. For example, imagine an office environment where an employee works at a computer. That person should be responsible for checking over their monitors and other appliances regularly for signs of obvious damage, and they should be reported if anything is found.

This allows employees to basically flag up damaged appliances long before PAT testing must be carried out, as a faulty appliance could easily develop in the period between PAT testing.

In order to make employees aware of the importance of user checks it is good practice for organisations to instruct them in the correct way to go about doing these tests, as well as the importance of actually doing them. Good practice dictates that the best way to do this is to actually instruct employees during their induction period, while posters about user checks can be placed throughout the premises to remind employees about the importance of the procedure.

It’s also worth having a regular monthly procedure where employees check over their appliances. This is especially true in schools or anywhere that children have access to electrical appliances. It may seem cumbersome, but it really is an essential part of electrical safety.

Formal Visual Inspections

Although it may seem similar to user checks, visual inspections are a pre-determined testing procedure that should be regularly completed.

According to figures found by the Health and Safety Executive (HSE) this part of the test flags up more than 90% of all recorded problems. It’s an essential part of the testing procedure because visual checks can flag up what PAT testing cannot, such as frayed cabling that exposes the wiring within.

The test itself requires the person doing the test to check over the cable, plug and appliance itself for any signs of obvious damage, often requiring the use of touch to feel for any obvious abrasions. Obviously this part of the test should be carried out only when the appliance is switched off, as dangerous faults such as exposed wiring could give electrical shocks if the appliance is live.

Visual inspections are also much different from PAT testing, as many of the electrical faults a PAT tester detects can only be detected by a PAT tester, whereas PAT testers cannot always detect problems that might be flagged up by visual checks.

This basically means that if you complete PAT testing, faults may go unnoticed because the visual inspections have not been carried out as well. This essentially means that while PAT testing flags up problems internally with appliances, visual inspections are of the utmost importance for checking on the external upkeep of a portable appliance.

Combined Inspection and Testing

Combined Inspection and testing is a full test carried out by a competent person who has received training.

The combined inspection and test starts with a visual inspection and also the opening of the plug top to inspect the condition of the plug and fuse.

The connections for Live, Neutral and Earth are checked to ensure that the plug is wired correctly and the connections are tight.

If the appliance is Class 1 there must also be an earth connection in the plug.

The plug is checked for signs of damage and also that the insulation on the pins of the plug complies with the latest standards. Again, this is more important in schools or anywhere where small children can access the plug.

The cable anchorage, the cable itself as well as the appliance anchorage is checked to ensure that the cable is secure. The appliance itself should be checked to ensure there are no cracks or damage to the casing and that the on/off switch operates correctly.

After the visual inspection has been carried out correctly then the electrical tests are undertaken with a portable appliance tester.

The person doing the test must understand the principles of PAT testing, what to look for and the consequences of what may happen if equipment is faulty (for example if the appliance is missing a good quality earth connection).

Results should be recorded or stored in software packages and all appliances should be given a PASS or FAIL sticker depending on whether they passed the test or not.

Failed appliances should not be used under any circumstances and should either by repaired or replaced. Repaired items must be subjected to another PAT test to ensure they are now safe for use.

Until repairs are carried out the appliance must be removed from service. Leaving an unsafe appliance in the same place increases the likelihood of someone using it, so hiding that appliance away protects both the company and the user.


All three of the above tests are a vital part of ensuring that your organisation is both electrically safe and also adheres to the regulations that govern electrical safety in the workplace.

In order to ensure you always are safe, it is important that you devise a system where each of these tests is regularly performed, recorded and any appliances that are deemed unsafe for use by any of the checks are removed from use.

The legislation covering Pat testing is the Electricity At Work Regulations 1989. It states that you must ‘maintain’ your electrical equipment to ensure that it is safe. This regulation covers not just portable appliances but any piece of electrical equipment within the workplace.

Written by Barry Atkins