Key Concepts

Short Circuit

It occurs when an unintended, low-resistance path is created in an electrical circuit, allowing a large amount of current to flow unexpectedly. It bypasses the normal path through the circuit's components, such as lights or appliances. The live wire directly connects to the neutral wire (or sometimes ground), creating a direct path for current. The resistance becomes extremely low, allowing excessive current to flow.

Grounding

• It is the process of connecting the metal parts of an electrical system or device to the earth via a conductor. This connection ensures that any unwanted excess electricity, such as from a power surge or lightning strike, is safely discharged into the ground.

• It provides a low-resistance path for surge currents to flow into the earth, minimizing damage to electrical devices and wiring.

• The grounding system (the third pin in the wall socket or grounding of the power strip) provides a low-resistance path for the excess electricity.

• The surge current follows this path, flowing through the ground wire (which is connected to the metal components of the socket and the grounding system in your building).

Wire Color Coding

Hot (Line/Phase) Wires - RED/BLACK - RIGHT

It carries the electricity from the power source to the electrical device or appliance.

Neutral Wires - BLACK - LEFT

The neutral wire provides a return path for the current.

Ground Wires - GREEN - TOP

Socket

It is a device that allows electrical equipment to connect to the power supply.

Types of Socket

1) Two-pin Socket:(No grounding)

2) Three-pin socket: (grounding)

3) Universal socket:

Safety Features

1) Children Shutter:

2) Surge Protection: It refers to a sudden and temporary increase in voltage or current in an electrical circuit.

Gang box (junction box / electrical box)

It is an essential component in electrical wiring systems. It is a container that houses electrical connections and devices such as switches, outlets, or circuit breakers.

Circuit Breaker

MCB (Miniature Circuit Breaker)

It is an essential safety device used in electrical systems to protect circuits from overloads and short circuits.

It automatically switches off the electrical supply to the circuit if the current flow exceeds safe levels, helping prevent potential damage to wires, devices, and the risk of fire.

Unlike a fuse, which needs to be replaced after it blows, an MCB can be reset after it trips, making it more convenient and cost-effective.

The MCB contains a bimetallic strip (for overload protection) and an electromagnetic coil (for short circuit protection).

When the current exceeds the rated value for a prolonged period, the bimetallic strip heats up, bends, and trips the switch to disconnect the circuit.

In the case of a short circuit, the sudden surge of current activates the electromagnetic coil, which triggers the mechanism to disconnect the circuit instantly.

RCCD (Residual Current Circuit Breaker)

An RCCD (Residual Current Circuit Breaker) is a safety device used in electrical systems to protect people from electric shocks and prevent electrical fires caused by ground faults or leakage currents.

The current flowing through the live wire equals the current returning through the neutral wire. The RCCD remains inactive.

If there is a difference between the live and neutral currents (called residual or leakage current), it indicates that some current is leaking to the ground, possibly through a person or faulty equipment. The RCCD detects this imbalance and trips the circuit, cutting off the electricity supply to protect against hazards.

Fuse

A fuse is a protective device used in electrical circuits to prevent damage from overcurrent (when the current exceeds the safe limit). It works by breaking the circuit when the current flowing through it becomes too high, thereby protecting electrical equipment from damage due to overheating or short circuits. It contains a thin wire or metal strip made from a material with a low melting point, such as copper, aluminum, or an alloy like tin-lead. When the current flowing through the fuse exceeds the rated current (usually due to a short circuit or equipment malfunction), the metal strip inside the fuse melts.

Types of Cable

Two-Core Cable (Twin-Core Cable)

This cable consists of two conductors: one live (phase) wire and one neutral wire.

Three-Core Cable

It contains three individual conductors (wires) enclosed within a single outer sheath.

Surge Protection Devices (SPDs)

Varister (Voltage-Dependent Resistor)

It is a surge protecting electronic component with an electrical resistance that varies with the applied voltage

Variac:

It is a type of adjustable transformer used to vary the output voltage. It is commonly used in applications where a controlled change in voltage is required, such as in testing or laboratory setups.

Rectifier

It is an electrical device that converts alternating current (AC) to direct current (DC). It typically uses components like diodes to allow current to flow only in one direction, converting the bidirectional AC signal into a unidirectional DC signal. Rectifiers are commonly used in power supplies for electronic devices.

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