There are two aspects to consider: the fixed wiring of the building and any ‘portable’ equipment plugged into it.
The fixed electrical wiring system should be tested at a regular interval and any remedial actions followed up. The time frame may vary but typically, in a workplace, this is every five years.
Checking your portable equipment is best done by someone with a reasonable level of competency and the regularity will vary on the type of use the equipment gets.
For example, the kettle in the Scout Headquarters might just need a visual check by users each time to ensure that the cord and plug look OK and the wires haven’t been pulled out.