This chapter shall apply to any person who engages in or offers to engage in, for the general public for compensation, plumbing, electrical or building-related mechanical work in the Town of Front Royal, such that his practice requires specialized skill or training, and that the public needs, and will benefit by, assurance of his professional and occupational ability.  Furthermore, no helper or laborer shall be employed to assist with any electrical, plumbing or building-related mechanical work requiring a building permit unless a certified plumber, electrician or building-related mechanical worker is present.