Questions for all...If you were to be asked " How often do I need to have my Electrical System checked ? " How would you answer, & what would you do to ensure that the service, circuits, etc were up to the task ? Also what have you found to be some common causes of problems ,when trouble shooting, and what did you do to remedy them ? I'll start with a common problem found in My area...frayed service entrance cable. Allows moisture to run down into the meterbase, & rusts the neutral connection. My calls come in as "lights flickering" & "getting real bright & then dim".. The remedy is usually a complete service upgrade. Let's see what a list we can compile.... I would like to make a check list to use when dealing with Realtors, & New Home Owners.
Megawatt: IMHO, this has to be a 'case-by-case' item, as there are too many variables to consider.
Resi 'maintenance checks' are probably unheard of around here, and the 'problems' are usually found when 'work' is being done.
Perhaps, using the age and appearance of a structure could be a good indicator.
Comm & Industrial (when they used to 'make' things here) are checked when we are at a site; the thoroughness of the 'check' is dependent on the owner. Some used to go for a full IR scan yearly; one facility had a full IR twice yearly.
Some towns around here have a 'property maintenance code' but the inspector is not State Lic as an Electrical Inspector, so it's mostly a 'visual' thing.