What is a lighting branch circuit?

A lighting branch circuit is the part of the electrical circuit that extends beyond the breaker circuit or storage fuse. From the breaker box to your home electrical appliances. Branch circuits are the last part of the main electrical circuit. They operate based on the type of load or their current carrying capacity, the branch circuits are divided into 120-volt branch circuits that provide power to normal stores and 240-volt circuits that power large electrical outlets.

 Illustration of circuit diagrams of a simple circuit, comparing pictorial and schematic styles.
CC0 1.0 | Image credits: https://commons.wikimedia.org | United States. Dept. of the Air Force

National Fire Protection Association (NFPA)

National Fire Protection Association (NFPA) has one of its parts as National Electrical Code (NEC). According to the NEC, the branch circuit basically has a circuit conductor between the overcurrent protection device (OCPD) and the electrical outlets. It permits a licensed electrician to install a branch circuit to ensure a safe and secure electricity supply.

The branch circuit, protected by a circuit breaker, is the most important safety feature for your home's electrical wiring. Its main function is to ensure an uninterrupted power supply to your household appliances. Most importantly, the branch circuit (with the help of a circuit breaker) identifies where most devices are connected, say in your kitchen or living room. It detects any defects and stops running.

Branch circuit amperage

There is a rule when it comes to branch circuits that the size of the branch circuit operators should not be under load. Also, the circuit cords should be able to carry the load of the branch circuit.

While the first circuits in your home will be properly fitted at all times - when the circuit is extended, the one-family or new cable system must have a proper circuit amperage gauge.

For instance, a 14-gauge copper wire is suitable for 15-amps, a 6-gauge copper wire for 60 amperes (amps), and a 2-gauge copper wire for 100 amps. If you attach insufficient wires to the circuit amperage, it causes a fire hazard.

To accommodate different types of load, two types of branch circuits, 120 volts and 240 volts, vary in the amount of power (or amperage) delivered. While 120-volt circuits are 15 or 20-amp circuits, 240-volt circuits have additional amperage (30, 40, 50, or 60-amp).

General lighting load

General lighting loads are used to power electric lights. They make up about a third of the commercial construction power in the US, but in residential buildings, they are usually 10 - 15%. General lighting loads in a building are usually measured in watts per square foot or square meter.

When deciding which lighting products to use, look for the efficiency (or light efficiency) of the products. The more efficient light sources reduce unit loads and permit more visible lights as they also reduce cooling loads.

Types of branch circuits

General-purpose branch circuits

The general purpose of the branch circuit is 120 volts used to provide lighting fixtures and storage areas for many portable items. There are often multiple purposes for branch circuits that provide lighting and shops in various rooms around a residential or commercial or industrial building.

Circuits with a maximum capacity of 15 amps using 14 gauge cables were common in older homes but are no longer recommended for new installations. Circuits rated at 20 amps using 12 gauge cables are recommended for the general purpose of branch circuits in modern power supply systems.

Appliance branch circuits

The 120 circuit voltages for the equipment circuit are used to supply fixed electrical equipment such as refrigerators, washers, and other large electrical appliances and appliances. Branch electrical circuits do not provide any lighting equipment. Electric branch circuits cannot exceed 20 amps.

These operate on only one machine and are usually required by the Code. They can be 120 or 240-volt circuits, and use electrical appliances such as electrical appliances, dishwashers, refrigerators, trash cans, air-conditioners, and dryers. Usually, any engine will need a dedicated receptacle in the circuit.

Individual branch circuits

Installed in permanent settings such as power lines, dryers, or air conditioning systems. These circuits usually permit directly to the distribution panel into a receptacle use and do not supply any other electrical equipment. These circuits can be of any size of amperage.

They sound like regions that provide common lighting in rooms. Typically, a lighting circuit will operate several rooms, and most homes will have several. Lighting circuits have an advantage over outlet circuits, each room will be left with lighting options when one circuit breaks. While operating the lighting cycle, for example, a plug-in lamp may be used to illuminate a space.

Wiring a lighting circuit

Wrapping up a simple lighting circuit can be a simple enough process for a trained electrician, and with little determination, anyone with basic skills can do it.

The basic lighting circuit consists of only three components: supply, switching, and light.

To provide light power, we need to connect you to the available services. This is usually a distribution board of some kind. However, in this guide, we will focus on the cords of the lighting circuit.

The connection to the distribution board will be discussed at another time.

When the light is connected to the live supply (Line and Cables) in receptacles, will light up. To make the switch happen we need to launch the switch on the Side of the Circle Line, successfully break it or make a circuit whenever we need to turn on or off the light.

Circuit breakers in branch circuits

The main service panel is controlled by the main breaker circuit which serves as the main power supply to the main service panel. This is usually a 100- to 200-amp amp-pole circuit breaker that currently provides 240-volts and supplies two 120-volt hot buses running directly to the panel.

Below the main circuit breaker, there are two rows of small circuit breakers, and these form the starting point for each branch that runs in all areas of your home to provide power. These single voltages are about 120 volts, touching only one bus bar on the panel; or will be a 240-volt breaker that connects to two 120-volt bus bars. Thus, your branch circuits will be 120-volt circuits supplying all lighting outlets and regular lighting; or will be 240-volt circuits or supply circuits that supply large electrical appliances, such as drying clothes, electricity distance, and central air units.

Context and Applications

This topic is important for professional exams in both undergraduate and postgraduate studies and in particular:

  • Bachelors in Electrical Engineering
  • Masters in Electrical Engineering

Practice Problems

Q1. What is the part called which is beyond the circuit breaker or fuse in an electric circuit?

  1. Lighting outlets
  2. General lighting load
  3. Branch circuit
  4. Receptacle

Answer: Option c

Explanation: A branch circuit is defined as that part of an electrical circuit that passes through a breaker circuit or
storage fuse.

Q2. Which of the following is used for the 15 amperes circuit amperage?

  1. 14 gauge copper wire
  2. 12 gauge copper wire
  3. 6 gauge copper wire
  4. None of the above

Answer: Option a

Explanation: 14 gauge copper wire is used for the 15 amperes circuit amperage.

Q3. Which of the following US standards measures the diameter of the electrical conductors?

  1. National electrical codes
  2. American wiring gauge
  3. Lighting outlet codes
  4. None of the above

Answer: Option b

Explanation: American wiring gauge (AWG) is the US standard measure used for the diameter of the electrical

Q4. Which of the following has the purpose of providing an uninterrupted power supply to appliances?

  1. Grounding permit
  2. Receptacles
  3. Lighting outlets
  4. Branch circuits

Answer: Option d

Explanation: It is branch circuits' main job is to provide an uninterrupted power supply to appliances.

Q5. Which of the following is the conductor between the service equipment and the branch-circuit overcurrent

  1. Minimum number load
  2. Lamp-holder receptacle
  3. Feeder
  4. None of the above

Answer: Option c

Explanation: Conductors between branch-circuit overcurrent devices and service equipment are called feeders. The
feeder circuits or the servers provide information about the safety and adequacy of the size and installation of these

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