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115 Electrical Safety for Employees: Basic
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Grounding

When you "ground" a tool or electrical system, you intentionally create a low-resistance path that connects to the earth. This prevents the buildup of dangerous voltages that could lead to an electrical accident.

Be sure to use proper grounding techniques to help prevent electrical accidents.

Grounding is normally a secondary protective measure to protect against electric shock. While it does not guarantee complete immunity from electric shock, injury, or fatality, it significantly reduces the risk. This effectiveness is further enhanced when grounding is combined with other safety measures covered in this course.

Under 1910.304, Wiring Design and Protection, there are circumstances in non-construction applications where both a service or system ground and an equipment ground are required. The service or system ground's primary function is to safeguard machines, tools, and insulation from damage. This system includes a wire known as the 'neutral' or 'grounded' conductor, which is grounded. In a standard low-voltage circuit, the white or gray wire is grounded at the generator or transformer and at the building's service entrance.

An equipment ground helps protect the equipment operator. It furnishes a second path for the current to pass through from the tool or machine to the ground. This additional ground safeguards the operator if a malfunction causes the tool's metal frame to become energized. The resulting flow of current may activate the circuit protection devices.

Knowledge Check Choose the best answer for the question.

2-3. What is the intentional creation of a low-resistance path that connects to the earth?