Final answer:
The Class B hard hat is indeed suitable for electrical work due to its protection against shock hazards, making the statement true. Plastic insulation on wires primarily prevents shock hazards and circuit breakers, and fuses act on thermal hazards but are ineffective against preventing shocks. GFIs protect against shocks by detecting imbalances in current flow due to differing wire lengths or ground faults.
Step-by-step explanation:
The Class B hard hat is designed to provide protection against shock hazards and is suitable for electrical work. Therefore, the statement that the Class B hard hat can be used for electrical work because it provides protection against shock is True. In electrical safety, the two types of hazards are thermal and shock. Plastic insulation on live/hot wires serves to prevent shock hazards since it acts as a barrier between the electrical conductor and any person or object that could become a path to the ground. In some cases, it also helps in reducing thermal hazards by preventing unintended contact that could lead to a short circuit, potentially causing a fire. However, it is primarily intended for preventing shock hazards.
Ordinary circuit breakers and fuses are designed to interrupt large currents that can cause fires or damage to electrical components (thermal hazards), but they may not act fast enough to prevent the lower levels of current that can cause harmful or lethal electrical shocks. Ground Fault Interrupters (GFIs) are more effective in preventing shocks because they can trip and break the circuit if there is an imbalance in the current between the live/hot and neutral wires, which may indicate a leakage path through a person.
If a GFI trips because the live/hot and neutral wires connected to it are significantly different in length, it could be due to the presence of a ground fault, caused by the different electrical resistance and reactance in the wires, which can create an imbalance in the current flow detected by the GFI.
It is also worth noting, although not directly related to the stated question, that while wood is generally an insulator, it can still conduct electricity, especially when wet. Hence, lightning can indeed travel through a tree to reach the Earth, making the statement True.