Md. Code Ann., Bus. Occ. & Prof. § 6-301

(a) Each county shall: (1) (i) adopt regulations that have qualifications that are at least as stringent as the qualifications under § 6–304 of this subtitle, to provide for the regulation and registration of master electricians, journeyperson electricians, or apprentice electricians; and (ii) register apprentice electricians, journeyperson electricians, or master electricians in the manner prescribed under § 6–103 of this title; or (2) (i) require a State license for providing electrical services as a master electrician, journeyperson electrician, or apprentice electrician; and (ii) enforce the provisions of this title.

(b) Each municipal corporation shall: (1) (i) adopt regulations that have qualifications that are at least as stringent as the qualifications under § 6–304 of this subtitle to provide for the regulation and registration of apprentice, journeyperson, or master electricians; and (ii) register apprentice electrician, journeyperson electrician, or master electrician registrations in the manner prescribed under § 6–103 of this title; (2) adopt the electrical rules and regulations of the county in which the municipal corporation is located; or (3) (i) require a State license for providing electrical services as an apprentice, journeyperson, or master electrician; and (ii) enforce the provisions of this title.

(c) Each licensed or registered master electrician shall display the State license number, the county registration number, or the municipal corporation registration number on each vehicle used on the job for providing electrical services.

(d) A county or municipal corporation may not adopt a resolution or enact a law that requires a person licensed or registered under this subtitle who is compliant with subsection (c) of this section to display additional license or registration numbers on each vehicle used on the job for providing electrical services.