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11.11111107117.31150, .: . ®SHA standards focus on the design and use of electrical equipment and systems. The standards cover only the exposed or operating elements of an electrical installation such as lighting, equipment, motors, machines, appliances, switches, controls, and enclosures, requiring that they be constructed and installed to minimize workplace electrical dangers. Also, the standards require that certain approved testing organizations test and certify electrical equipment before use in the workplace to ensure it is safe. Electricity: The Basics Electricity flows more easily through some materials than others. Some substances such as metals generally offer very little resistance to the flow of electric current and are called " conductors." A common but perhaps overlooked conductor is the surface or subsurface of the earth. Glass, plastic, porcelain, clay, pottery, dry wood, and similar substances generally slow or stop the flow of electricity. They are called " insulators." Even air, normally an insulator, can become a conductor, as occurs during an arc or lightning stroke. Pure water is a poor conductor. But small amounts of impurities in water like salt, acid, solvents, or other materials can turn water itself and substances that generally act as insulators into conductors or better conductors. Dry wood, for example, generally slows or stops the flow of electricity. But when saturated with water, wood turns into a conductor. The same is true of human skin. Dry skin has a fairly high resistance to electric current. But when skin is moist or wet, it acts as a conductor. This means that anyone working with electricity in a damp or wet environment needs to exercise extra caution to prevent electrical hazards. What causes shocks? Electricity travels in closed circuits, normally through a conductor. But sometimes a person's body -- an efficient conductor of electricity -- mistakenly becomes part of the electric circuit. This can cause an electrical shock. Shocks occur when a person's body completes the current path with: both wires of an electric circuit; one wire of an energized circuit and the ground; a metal part that accidentally becomes energized due, for example, to a break in its insulation; or - another " conductor" that is carrying a current. -- - -- --- When a person receives a shock, electricity flows between parts of the body or through the body to a ground or the earth. What effect do shocks have on the body? An electric shock can result in anything from a slight tingling sensation to immediate cardiac arrest. The severity depends on the following: