How often Do I do this?
According to the HSE website, you should test ‘often enough that there is little chance of deterioration leading to danger’. This is further detailed on the Electrical Safety First website, which suggests:
10 years for an owner-occupied home
5 years for a rented home
3 years for a caravan
1 year for a swimming pool
when a property is being prepared for letting
before selling a property or buying a previously-occupied property
For commercial and industrial premises, periods vary with the type of industry and risk factor, but 1-5 years is the usual recommendation – unless your insurer specifies otherwise.