Electric shock is the physiological reaction or injury caused by electric current passing through the (human) body.Typically, the expression is used to describe an injurious exposure to electricity.It occurs upon contact of a (human) body part with any source of electricity that causes a sufficient current through the skin, muscles, or hair. Very small currents can be imperceptible.
Larger current passing through the body may make it impossible for a shock victim to let go of an energized object.Still larger currents can cause fibrillation of the heart and damage to tissues. Death caused by an electric shock is called electrocution.Źródło: https://en.wikipedia.org/wiki/Electric_shock
Master electricians go through extensive on-site and classroom training, with work in more formal settings such as schools or colleges. The designation "master" is only given to electricians who can display extensive job knowledge and are tested to have an extensive understanding of the electrical safety code. There are no formal certifications of the "theatrical title, master electrician", as there are in some of the more mainstream trades, but in March 2003 ESTA, which merged with PLASA in 2010, developed a certification process. Those who pass this rigorous test will become ETCP Certified Entertainment Electricians - and will be recognized as the industry's best. The stagehands union, IATSE, come close in that they offer apprentice and journeyman levels of certification. In the future, IATSE, or some of the larger local affiliations may form a more formal method of certification, which may include the title of master electrician.
In the meantime, almost every production, from high school shows to Broadway uses the term to describe their primary electrician, regardless of their skill level or experience.Źródło: https://en.wikipedia.org/wiki/Master_electrician
On the other hand, cheaper does not mean better, and looking for an electrician on the Internet need to be careful..