PAT Testing AtoZ – V is for Visual

Sometimes we visit sites where certain things can’t be turned off. You might have a highly specialised printer, a sensitive piece of lab equipment, or just a server which needs to stay online.

In this case, we carry out a formal visual inspection. But what is that?

Doing it by the book

According to the IET Code of Practice which all PAT testers should be following, the first part of a visual inspection is checking the suitability of the equipment for the environment. In server rooms, for example, are adequate measure in place to prevent the build up of dust? It sounds bizarre, but server rooms can get very warm and if there is too much dust a server could overheat and ignite.

Risks of mechanical damage, weather ingress, high or low temperatures, water, and dirty conditions all have to be considered.

Next, we need to check that it is possible to switch the appliance off without difficulty in normal conditions. Emergency switch off procedures should also be considered.

Since the appliance can’t be turned off we can’t check the wiring inside the plug. However, the appliance lead can be checked to ensure it is intact, and the plug can be examined for any obvious signs of damage or overheating. The appliance casing should also be checked over to ensure it’s intact.

What’s the point?

The majority of items which fail PAT testing do so during the formal visual inspection. We can even fail many items just by casting an experienced glance over them. This allows us to highlight any potential safety issues with the appliance even though we haven’t run it through a full PAT test.

As the Code of Practice states:

Frequent inspections and tests will not prevent damage occuring if the equipment is unsuitable for the particular application. Replacement by suitable equipment is required.

IET Code of Practice for In-Service Inspection and Testing of Electrical Equipment, 4th Edition.

To arrange for one of our engineers to come out and do your PAT testing, just get in touch! You can call us on 07518 688 233 or email us at

Until next time,


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