Any person who lets a residential accommodation (such as houses, flats, bedsits, etc) as a business is lawfully required to ensure the equipment supplied as part of the tenancy is safe to use.
Requirements by the Electrical Equipment (Safety) Regulations 1994 states that all mains electrical equipment (cookers, washing machines, kettles, microwaves etc), whether new or otherwise, supplied with the accommodation must be safe to use. As a Landlord, you need to regularly maintain the electrical equipment you supply to ensure it's safety.
The supply of goods occurs at the time of the tenancy contract. Therefore, it is essential that the property is checked prior to the tenancy so that all goods supplied are in a safe working condition. A record should be made of the goods supplied as part of the tenancy agreement and of all checks made on those goods. The record should comprise of the company that tested the items and a date and time.
We would strongly advise you to have the equipment checked before each let begins and it would be good practice to have the equipment checked regularly during the let too. We would advise you retain test reports detailing the equipment, the tests carried out and the results as well.