Final answer:
A Ground Fault Interrupter (GFI) is crucial for protecting workmen from electrical shocks as it detects loss of current through unintended paths. Other safety devices include rubber insulating gloves and boots, grounded plugs, and isolation transformers.
Step-by-step explanation:
The devices used to protect workmen from electrical shock with tools and extension cords include Ground Fault Interrupters (GFIs), rubber gloves and boots, and grounded plugs, among others.
A GFI is a device that prevents shock by detecting the loss of current to unintentional paths, such as through a person's body. An isolation transformer provides additional protection by insulating the device being powered from the original source to prevent shock.
It's also important to note that our bodies conduct electricity well due to water content, so safety precautions such as using insulated shoes when working with electrical equipment are essential.
More advanced systems utilize a three-wire system with live/hot, neutral, and earth/ground wires to further protect against electrical hazards.