49 CFR §246.120

1. (a)After FRA has approved a railroad's certification program, a railroad shall not permit or require a person to serve as a signal employee, as defined in § 246.7, unless that railroad determines that:
   1. (1)The person is a certified signal employee; and
   2. (2)The person either:
      1. (i)Is qualified, as defined in § 246.7, on the signal system equipment and signal-related technology (whether existing or new) and therefore may reasonably be expected to be proficient on all safety related tasks the person is assigned to perform; or
      2. (ii)Is working under the direct and immediate supervision of a mentor or qualified instructor.
2. (b)If a person is called to perform work on signal system equipment or signal-related technology that they are not qualified on, the person must immediately notify the railroad that they are not qualified on the signal system equipment or signal-related technology.
3. (c)A person shall no longer be considered qualified on signal system equipment or signal-related technology if they have not performed work that requires certification pursuant to this part on signal system equipment or signal-related technology in the previous 12 months.
4. (d)Each railroad shall adopt and comply with a program meeting the requirements of this section. When any person (including but not limited to a railroad; any manager, supervisor, official, or agent of a railroad; any owner, manufacturer, lessor, or lessee of railroad equipment, track, or facilities; any employee of such owner, manufacturer, lessor, lessee, or independent contractor or subcontractor) violates any requirement of a program which complies with the requirements of this section, that person shall be considered to have violated the requirements of this section.