The law stated that a landlord is required to ensure that the wiring in a private rental property is safe and that any appliances provided for the tenant are safe to use.
As best practice, the landlord should carry out regular basic safety checks to ensure the mains electrics and any appliances provided by the landlord (e.g. electric cookers, washing machines, fridge freezers etc.) remain in good working order.
If rented property is a house in multiple occupation (HMO), then the landlord is legally required to have the electrical installation checked at least every five years by a suitable qualified person. Said person will then provide a certificate to the landlord which will highlight any areas worth addressing and will state how long the certificate is valid for; this is dependent upon any defects found.