Found this recently at an industrial site, needless to say never use foil as a fuse!!!

We are now members of the PATTA (Portable Appliance Testing Trade Association). 

patta.co.uk

How often do I need to PAT test?

There are no rules on how often your equipment needs a PAT test. It is entirely up to the ‘duty holder’ (the person allocated with the responsibility for the electrical equipment in your business) to assess the risk and decide on the frequency of inspections.  This is determined by the type of equipment, how often it is being used and whether the working environment is considered low or high risk.

User checks

The person that uses the equipment regularly will be in the best position to know if it is in a safe condition and working properly. 

It is worth training your staff to look out for signs of wear and tear such as cracked plugs, faulty strain relief on the cords and signs of heat damage.

Should the user become aware of any fault then the appliance must be disconnected from the mains and quarantined and the fault reported to the 'responsible person' in the company.

This 4 way extension lead socket overheated and melted more than likely because it was overloaded. 

 I have to say the extension lead was not of the best quality.

The plug had started to bulge on the side making it more obvious there was a fault.