Cal. Code Regs. tit. 8, § 5497 – Operating Instructions.

(a) For installations which require any operation of equipment by the user, legible instructions shall be maintained at operating locations.
(b) A qualified person shall be in attendance at all times while the mobile hydrogen supply unit is being unloaded.
(c) Each mobile liquefied hydrogen supply unit used as part of a hydrogen system shall be adequately secured to prevent movement.
(d) The mobile hydrogen supply unit shall be grounded.