Below if from the City of San Diego. See also PERMIT NOT NEEDED:

Addition or changes to a building's existing system; for example, moving or adding an electrical outlet
2: Electric - meter reset, miscellaneous wiring (relocate electrical outlets, re-wiring, new panel etc)
3: Gas - meter reset, piping repair or alteration
4: Plumbing - water heater replacement , water or sewer piping repair, alteration, replacement
5: Installation or replacement of Forced Air Unit (FAU) and Air Conditioner (A/C) units, exhaust fans, kitchen hoods and more.
6: May be required for kitchen or bathtub/shower enclosure remodels if removal of drywall, modification of wood framing or  replacing/installing new
finishes is proposed
7: If the value of the work exceeds $1,000.00, then a permit is required unless excluded per PERMIT NOT NEEDED: