California Code, Labor Code - LAB § 6700

(a) Any employer who causes or allows the use of any flammable or combustible material for the installation acceptance pressure test of any gas houseline or piping shall be conclusively presumed to be maintaining an unsafe place of employment.

(b) Any employer who causes or allows gas pipelines to be tested with gas at pressures in excess of that permitted by applicable sections of the American Society of Mechanical Engineers Code for Pressure Piping shall be conclusively presumed to be maintaining an unsafe place of employment.