Legal Question in Real Estate Law in California

Usually, there will be a municipal or county ordinance prescribing what the building inspectors may and/or must do, and these ordinances are then subject to court scrutiny under the Fourth Amendment of the U.S, Constitution, which prohibits "unreasonable searches and seizures."

In many instances, the courts, including the U.S. Supreme Court, have approved the searches by building inspectors on the basis that they are reasonably necessary to promote safe buildings and safe uses of buildings. There have been strong dissents. The inspectors and the local ordinances they work under must limit the scope of these inspections to civil rather than criminal matters, for example. You still need a warrant, or "hot pursuit," to enter someone's home in a criminal investigation.

So, I'd guess what the inspector did is more likely legal than not. There are several cases you can look up and read where courts of appeal have discussed these matters. One that might be a useful starting point is Camara v. Municipal Court of San Francisco (1965) 237 Cal.App.2d 128.

Mr. Whipple seems to be under the mistaken impression that the inspector entered your home. My understanding from your description is that the area in question is from your breaker panel on the exterior of your home to the street. Unless the inspector had to enter an enclosed area to visually inspect your main power wiring, you had no constitutionally protected interest. Inspectors are completely free to inspect anything that any average man on the street could come look at. The Constitution is only implicated in areas where there is a reasonable expectation of privacy.