Final answer:
When working with high-voltage circuits and energized equipment, employing electrical safety systems like circuit breakers, fuses, GFCIs, and ensuring proper grounding through a three-wire system are essential for preventing thermal and shock hazards. It is also important to take personal safety precautions, like wearing insulated shoes. Specialized equipment that can handle large currents and voltages, like circuit breakers with insulating gas, are required for high-voltage applications.
Step-by-step explanation:
When installing or repairing Control and Instrumentation (C&I) systems, communication cables, and internal systems that may expose you to energized equipment, it is paramount to consider electrical safety systems and devices to avoid both thermal and shock hazards. It is necessary to make use of circuit breakers and fuses to interrupt excessive currents and prevent potential thermal hazards. The application of a three-wire system, which includes live/hot, neutral, and ground wires, provides additional safety by grounding the neutral wire and the case of the appliance.
In locations where there might be a risk of ground faults, a Ground Fault Circuit Interrupter (GFCI) or a Ground Fault Interrupter (GFI) is essential, as it can prevent shock by detecting the loss of current to unintentional paths. Additionally, the use of an isolation transformer can insulate the device being powered from the original power source to prevent shock. Given that the human body is a good conductor of electricity, safety precautions, such as wearing insulated shoes, play a critical role in preventing electricity from finding a pathway through the body to the ground, especially when dealing with high-power tools or circuits.
For installations involving high-voltage circuits (600 V or above) or low-voltage power circuits with high current flow, specialized fuses and circuit breakers that can handle large voltages and currents are necessary. These may include the use of insulating gas and gas jets to blow out sparks that can occur when interrupting high-voltage electricity. Unlike direct current (DC), alternating current (AC) provides periodic zero-current instances that can assist in extinguishing electrical arcs during breaker operation, which contributes to its preference in certain safety applications.