It's hard to answer this one with certainty. The Health and Safety at Work Act, The Using Electric Equipment Regs etc. make it clear that ALL electrical equipment used for work must be safe. That's everything from the mains supply transformer in the street outside, to the hand dryer in the loo. What is not quite so cut and dried is what needs to be done. There are guide lines from IET (4TH Ed) that say office equipment (as that's what I understand your friend uses) of Class I should be tested and inspected every 2 years. But it is only guidance. As he or she only ones a duty of care to themselves they can get away with not following the guidance. They can be sensible and do regular visual inspection and feel safe.In this particular instance. I’m referring to a company of one person, who works within his his own rented property within a larger building, who uses power tools to carry out repairs. Would he need to PAT Test his appliances or is he not required as he has no employees.
HOWEVER
If their electrical equipment is used in interaction with the PUBLIC that makes all the difference. Do they have visitors who make themselves a brew? A cleaner using a vacuum? A sales rep using a hand dryer?
In these cases they owe a duty of care. In these cases, they must ensure all electrical equipment is safe.
How do you do that!? You inspect. You keep a register. You test.
Hope that helps