Electrical Installation Trivia

Electric shock occurs when a person becomes part of an electrical circuit. This typically happens when the person comes into contact with both a source of electricity and the ground, thereby completing the circuit and allowing electrical current to pass through the body. This can result in injury or even fatality, depending on the voltage and other factors.

In an electrical circuit, it is important to earth or ground all exposed metal. This is done to provide a safe path for electric current in case of a fault or short circuit. By connecting the metal to the earth, any excess current will flow harmlessly into the ground instead of causing damage or posing a risk to people. This helps to prevent electrical shocks, fires, and other hazards that could occur if the metal was not properly earthed.

Before working on a circuit, it is necessary to switch off the power supply. This is important to ensure safety and prevent any electrical accidents or damage. By switching off the power supply, you are cutting off the flow of electricity and reducing the risk of electric shock or short circuits. It allows you to work on the circuit without any power running through it, minimizing the chances of getting injured or causing any damage to the components.

The generally accepted lethal level of electrical shock current passing through a human body is about 30 milliamperes (mA). This level of current, particularly when passing through the heart, can be fatal due to its ability to disrupt the electrical signals that manage the heartbeat, potentially leading to cardiac arrest. Safety devices like Ground Fault Circuit Interrupters (GFCIs) are designed to trip and cut off the power if a current as low as 5mA to 6mA is detected leaking, well below the lethal threshold, to provide an additional margin of safety.

Electricity is made at a power plant by a generator. A generator is a device that converts mechanical energy into electrical energy. It consists of a rotating coil of wire called an armature, which is connected to a source of mechanical energy such as a motor. As the armature rotates within a magnetic field, it induces a flow of electrons, generating electricity. Therefore, a generator is the correct answer for how electricity is made at a power plant.

The shaft in a screwdriver serves the purpose of connecting the head, which interacts with the screws, to the handle that provides the user with a grip. It ensures the efficient transmission of rotational force while using the tool.

The correct answer is "Fuse only once and, but CB many times". This means that a fuse can only be used once and needs to be replaced after it blows, while a circuit breaker can be used multiple times as it can be reset after tripping.

A switch is an electrical component that manually opens or closes an electrical circuit, allowing current to flow or stop flowing through the circuit. This control is essential in everyday devices like lights and appliances, where it enables the user to turn power on and off at will. Switches are fundamental components in household and industrial electrical systems, offering simple, effective control over electrical power.

The 'IP rating' in electrical installations refers to the Ingress Protection rating system, which classifies and rates the degree of protection provided by mechanical casings and electrical enclosures against intrusion from different foreign bodies (tools, dirt, etc.) and moisture. This rating system helps in determining how well an enclosure protects the internal components of electrical devices from external elements, which is critical for ensuring durability and safety in various environmental conditions.

A cable gland is used in electrical installations to securely attach and seal the end of a cable to the equipment. This device provides strain relief and connects the cable, enclosure, or conduit in a way that maintains the integrity of the sealing and provides necessary environmental protection. It ensures that electrical connections remain tight and protected from dust, moisture, and mechanical stress, which are crucial for maintaining safety and functionality in electrical systems.