WHO does this inspection and how often is it done?
It could be the person who installed the system originally, but it could be anyone.
How often? That's another debate in itself. Guidelines are generally that a domestic system should be inspected at least every 10 years and commercial at least every 5 years, but the standard inspection forms leave a space for the person carrying out the P.I.R. to insert his recommendations for when the next inspection should be carried out.
So again, it's open to personal opinion to a large degree. If the person doing the P.I.R. feels that the wiring, environment, use/abuse make it sensible to inspect more often, then he can note that on the report.
Only certain places (filling stations, theatres, etc.) have anything mandating regular inspections at more frequent intervals by law. When it comes to domestic, it's more a case of an inspection being carried out only when somebody asks for one -- Mortgage company, insurance assessor, etc.
So in practice, there are plenty of homes which
never get a regular P.I.R. from the time they were originally wired.
