Legislation passed in 1999 requiring all electricians who work for a C-10 electrical contractor to be certified by the state of California. Regulations from that legislation were put in place in 2002, setting deadlines for all categories of electricians. Many of those deadlines have already passed.
To continue to work as an electrician after the deadline has passed, a person must be one of the following: certified by having taken and passed the exam or an apprentice in a state approved program or an electrician trainee.
If a person wants to perform electrical work for a C-10 contractor and does not yet qualify to take the certification exam because of lack of work experience or related instruction, can do so legally by registering as an electrician trainee.
For more details:
California Labor Code definition of an electrician trainee
Deadlines for electrician certification
Electrician trainee registration form
An electrician trainee must be enrolled in a state approved school and under the supervision of a certified electrician that supervises only one electrician trainee.