In NC it has been required for a long time (70's).
Exerpt from the state statutes (I have edited this to eliminate some legal jargon and numbers)
(b) No person may perform electrical inspections pursuant to this Part unless he has been certified as qualified by the Commissioner
of Insurance. To be certified a person must pass a written examination based on the electrical regulations included in the
latest edition of the State Building Code as filed with the Secretary of State. The examination shall be under the supervision of and
conducted according to rules and regulations prescribed by the Chief State Electrical Inspector or Engineer of the State Department.
The rules and regulations may provide for the certification of class I, class II, and class III inspectors, according to the results of
the examination. The examination shall be based on the type and character of electrical installations being made in the territory
in which the applicant wishes to serve as an electrical inspector. A class I inspector may serve anywhere in the State, but class II
and class III inspectors shall be limited to service in the territory for which they have qualified.
The Commissioner of Insurance shall issue a certificate to each person who passes the examination, approving the person for service
in a designated territory. To remain valid, a certificate must be renewed each January by payment of an annual renewal fee of
one dollar ($1.00). The examination fee shall be five dollars ($5.00).
If the person appointed by a county as electrical inspector fails to pass the examination, the county shall continue to make appointments
until an appointee has passed the examination. For the interim the Commissioner of Insurance may authorize the
county to use a temporary inspector.
The provisions of this subsection shall become void and ineffective on such date as the North Carolina Code Officials Qualification
Board certifies to the Secretary of State that it has placed in effect a certification system for electrical inspectors pursuant to
its authority granted by Article 9C of Chapter 143 of the General Statutes.
153A-351.1. Qualifications of inspectors. - On and after the applicable date set forth in the schedule in G.S. 153A-351, no county
shall employ an inspector to enforce the State Building Code as a member of a county or joint inspection department who does
not have one of the following types of certificates issued by the North Carolina Code Officials Qualification Board attesting to his
qualifications to hold such position: (i) a probationary certificate, valid for one year only; (ii) a standard certificate; or (iii) a limited
certificate, which shall be valid only as an authorization for him to continue in the position held on the date specified in G.S.
143-151.10(c) and which shall become invalid if he does not successfully complete in-service training prescribed by the Qualification
Board within the period specified in G.S. 143-151.10(c). An inspector holding one of the above certificates can be promoted
to a position requiring a higher level certificate only upon issuance by the Board of a standard certificate or probationary certificate
appropriate for such new position. (1977, c. 531, s. 4.)