Pen. Code, § 4530

(a) Every prisoner confined in a state prison who, by force or violence, escapes or attempts to escape therefrom and every prisoner committed to a state prison who, by force or violence, escapes or attempts to escape while being conveyed to or from that prison or any other state prison, or any prison road camp, prison forestry camp, or other prison camp or prison farm or any other place while under the custody of prison officials, officers or employees; or who, by force or violence, escapes or attempts to escape from any prison road camp, prison forestry camp, or other prison camp or prison farm or other place while under the custody of prison officials, officers or employees; or who, by force or violence, escapes or attempts to escape while at work outside or away from prison under custody of prison officials, officers, or employees, is punishable by imprisonment in the state prison for a term of two, four, or six years. The second term of imprisonment of a person convicted under this subdivision shall commence from the time he or she would otherwise have been discharged from prison. No additional probation report shall be required with respect to that offense.

(b) Every prisoner who commits an escape or attempts an escape as described in subdivision (a), without force or violence, is punishable by imprisonment in the state prison for 16 months, or two or three years to be served consecutively. No additional probation report shall be required with respect to such offense.

(c) The willful failure of a prisoner who is employed or continuing his education, or who is authorized to secure employment or education, or who is temporarily released pursuant to Section 2690, 2910, or 6254, or Section 3306 of the Welfare and Institutions Code, to return to the place of confinement not later than the expiration of a period during which he or she is authorized to be away from the place of confinement, is an escape from the place of confinement punishable as provided in this section. A conviction of a violation of this subdivision, not involving force or violence, shall not be charged as a prior felony conviction in any subsequent prosecution for a public offense.