Cal. Health & Safety Code § 114367.4

(a)
1. (1) A city, county, or city and county shall not prohibit the operation of, require a permit to operate, require a rezone of the property for, or levy any fees on, or impose any other restriction on, a microenterprise home kitchen operation in any residential dwelling for zoning purposes. A microenterprise home kitchen operation shall be a permitted use of residential property in any residential dwelling for zoning purposes if the microenterprise home kitchen operation complies with both of the following criteria:
  1. (A) Abstain from posting signage or other outdoor displays advertising the microenterprise home kitchen operation.
  2. (B) Be in compliance with applicable local noise ordinances.
2. (2) This subdivision does not supersede or otherwise limit the investigative and enforcement authority of the city, county, or city and county with respect to violations of its nuisance ordinances.
(b) The use of a residence for the purposes of a microenterprise home kitchen operation shall not constitute a change of occupancy for purposes of the State Housing Law (Part 1.5 (commencing with Section 17910) of Division 13), or for purposes of local building and fire codes.
(c) A microenterprise home kitchen operation shall be considered a residence for the purposes of the State Uniform Building Standards Code and local building and fire codes.