Cal. Insurance Code § 9095

(a) (1) An association may, if it has issued an insurance policy against fire, endorse that policy to extend the coverage thereof to include loss or damage caused by windstorm, cyclone, tornado and hail, explosion, riot, riot attending a strike, aircraft, vehicles and smoke, and to include waiver of the fallen building clause. (2) An association may also insure against any or all of the following: (A) Water damage from plumbing and heating systems. (B) Rupture or bursting of steam or hot water heating system. (C) Vandalism or malicious mischief. (D) Glass breakage. (E) Ice, snow, and freezing. (F) Fall of trees. (G) Collapse. (H) Burglary and theft. (I) Mysterious disappearance. (J) Liability. (b) As used in this section “explosion” does not include explosions (1) of any boiler, heater, or other fired pressure vessel, caused by pressure of contents, (2) of any unfired pressure vessel or of any piping caused by pressure of contents or vacuum, (3) of any engine, turbine, compressor, pump, or wheel, (4) of any electrical apparatus, or (5) of any other machine having moving or rotating parts. This restricted definition of “explosion” does not exclude loss or damage by fire only where fire ensues. (c) As used in this section, the terms “boiler,” “heater,” and “pressure vessel,” do not include hot water heaters used solely to provide hot water for delivery to faucets for domestic purposes and having a storage capacity of not more than 50 gallons.