What Is The Maximum Current Rating Of A Distribution Board?

13th May 2023

Electrical systems and appliances can handle only a certain capacity of current. If the current or power increases, it can lead to overload and damage the entire system.

It can even cause fires or system failure. Because of this reason, the current rating is given on the back of the system or device. 

You need to check the current rating to know how much amount of power it can hold or supply. When it comes to the distribution board, you need to check the maximum current capacity. 

It is different from one country to another as per standards and specifications. For example, the current rating in North America will be different from European countries. 

If you want to know about the maximum current rating of a distribution board, we can help you. In this article, we are going to discuss the current rating of different types of distribution boards.

What Is Current Rating?

In engineering, power or current rating refers to the maximum amount of current a piece of equipment can handle. The term can apply to both electrical and mechanical power. To find out a device’s current, look for a mark identifying its rated capacity. 

A fuse’s wattage and voltage are also indicated on the fuse’s label. The ampere rating of a fuse is based on its voltage rating. The ampere rating is the highest current a fuse can handle at its rated voltage. 

The interrupting and operating ratings are printed on the circuit breaker handle. A fuses current is its maximum capacity and may be extended indefinitely without deterioration of the fuse element.

When a fuse is rated for a certain voltage, the manufacturer will use the nominal ampere value to determine the maximum amount of current that the fuse can handle. 

This value is the maximum amount of current a fuse can handle in a specific voltage and time. This information is provided on the rating plate.

What Is A Distribution Board?

HA IP65 Waterproof Distribution Board

A distribution board is a device that connects individual light circuits and machine points to a central power supply. The distribution board receives live and neutral leads from power cables and feeds each circuit with appropriately rated circuit breakers. 

In addition, each individual circuit is fed with an appropriate breaker that allows it to be isolated if necessary. A distribution system is usually divided into several zones or zones. 

A distribution board is also useful for connecting switches and earth leakage units. They are used to provide power to individual circuits. Most boards feature a single incoming supply cable. This cable is connected to a main breaker or fuse. 

The board also contains a residual current detector to protect the home from fire or ground fault shock. The panel is also commonly known as a consumer unit. The consumer unit connects the incoming power to the mainboard.

What Is The Maximum Current Rating Of A Distribution Board?

The maximum current rating of a distribution board must not be more than the rated capacity. This is the maximum value for a single-phase, three-phase, or emergency power panel. 

There are different types of panels, each of which serves a specific use. Throughout a building, they are located in electric closets. Some boards are used in commercial applications, while others are for residential use.

The general rule states that a single circuit breaker must not exceed 80% of its rated capacity. Unlike other rules, the limit is only on total continuous load on circuit breakers.

To determine the maximum current rating for a particular panel, you must investigate the available fault current from the components of the panel. To determine the peak current let-through, you must identify the component with the lowest capacity. 

It is important to note that the maximum current rating of a distribution board should be equal to the total fault current of all the components. The maximum current rating depends on the type of board. Here are the three common types of distribution boards and their current rating. 

  • Single Phase Distribution Board:

The Single Phase Distribution Board) is one of the most commonly used electrical components in commercial buildings. Unlike a traditional MCB, an SPNDB has a 125A current rating as a standard. 

These are available in five different sizes, with four, seven, ten, and sixteen single-pole outgoing ways. They are available with a choice of metering solutions, allowing you to view and record the electrical consumption in real-time. 

The breaker switch handles are covered by a door, and all panelboards have a dead front to prevent operators from accidentally touching live electrical parts. 

They have a series of bus bars to carry the current from the incoming line conductors to the breakers. These breakers are connected to each other via a bolt-on connection. 

These boards have earth fault protection and can handle 30mA-300mA applications. A direct connection terminal arrangement is also available for applications that do not require local isolation. There are also single-phase kits available.

  • Three Phase Distribution Board:

There are two common types of electrical connections, three-phase and single-phase. A three-phase connection carries voltage between the two phases and is usually 230V AC, while a single-phase connection carries voltage between the lines. 

For example, the voltage between line one and line two is 400V AC, and the voltage between the phases is 230V AC. In most cases, you will connect lighting and small appliances between the two phases. 

Larger equipment is typically connected between two phases. Generally, a three-phase connection will be used for larger equipment, such as an electric heater or air conditioner. A single-phase connection, however, is a common type for lighting, receptacles, and other small loads. 

  • Miniature Circuit Breaker:

A Miniature circuit breaker (MCB) has a maximum current rating and is used to protect electrical equipment and appliances in a given area. When the rated load current exceeds this limit, a thermal trip element heats up and bends a bimetallic sheet allowing the free tripping mechanism to trip. This type of tripping characteristic is suitable for protecting household appliances and personal safety.

When choosing an MCB, it’s important to understand how much current it can safely handle. The maximum current capacity of MCB is 0.5 to 100 A. In general, an MCB’s breaking capacity should be more than the fault level that could occur. For domestic applications, however, this figure is not necessary because the standard breaking capacity is 10kA.

Here’s a video on How to Calculate Circuit-Breaker Rating , i hope it will be helpful for you.

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