What Is A Class 2 Power Supply? Understanding Power Supply

From homes to offices, people use electrical devices for one reason or the other. Electrical devices essentially use electric power to function. 

At the heart of an electric system is a power supply. The power supply is a sort of intermediary between an electric power source and an electric load. By load, we mean the task we want to perform. An example is the turning of the blades of an electric blender.

In this article, we look at what a class 2 power supply is, including other related information. Now, let’s answer the question.

What Is A Class 2 Power Supply?

Class 2 refers to power supply devices that meet National Electric Code (NEC) regulations for wiring specifications and power restrictions to minimize the risk of shock or fire.

Generally, class 2 circuits’ power devices require low energy and voltage like intercoms; security systems, low-voltage lighting, and public address systems (PAS).

Class 2 circuits can prevent shocks and fires by limiting power and voltage to the load. Class 2 power supplies usually have the words “Class 2 Power Supply” on their labels.

Specifically, a class 2 power supply limits 30V circuits to 100VA to prevent electrical accidents. What does this mean for you?

When it comes to electricity, safety concerns remain paramount across the world. Therefore, using and installing devices like power supply in a particular location must comply with safety standards peculiar to that region.

The National Electric Code (NEC) defines these standards for the safe installation of electric wiring, relevant for class 2 power supplies. 

Before we look at the specific requirements for a class 2 power supply, let us first learn about the power supply. What is a power supply?

About Power Supply

A power supply is an electric device that provides electrical energy to a load. The basic role of a power supply is to convert electric power from an electric source to the right current, voltage, and frequency parameters for the load. 

Some power supplies are independent units, while others are integral to the load appliances they support. Examples of integrated power supplies are those found in consumer electronics and desktop computers.

Now that we have defined the power supply, let us look at the NEC’s requirements for a class 2 power supply unit. 

Class 2 Power Supply Requirements 

Power supplies usually offer protection from short circuits or overload as these could destroy the supply unit or cause a fire. 

The National Electric Code (NEC) provides safety wiring and power requirements for a class 2 power supply. Let us examine them in more detail.


A Class 2 power supply must come with In-Wall Rated wire for permanent installation inside walls or floors where insulation may be present.

These wiring specifications serve to keep the wire from splitting or melting. The power source could become a potential fire hazard if manufacturers do not meet these conditions.


The power limitation is the essential aspect of the NEC Class 2 standard. These restrictions function to protect you from electric shock or to overheat from high currents.

A power supply is class 2 compliant if the 12V drivers draw less than 60W and the 24V drivers draw less than 96W. For instance, LED power supplies can convert 120V power into low-voltage 12V or 24V power.

However, larger projects, such as house renovations or commercial building construction, require more power to operate multiple lightning. In this case, you can use large wattage multi-tap power supplies such as a 12V 240W power supply for these projects. 

High-wattage multi-tap power supplies have distinct power outputs. Because each output has its circuit breaker, a power surge in one will not affect the others.

Using a single large power source instead of many power supplies for a large project is more convenient and cost-effective.

Functions Of  A Power Supply 

Electricity supplies may need to adjust voltage, convert power to direct current, or control power for a more consistent output voltage.

These parameters will help you figure out the kind of electrical supply you need. Buying a gadget with too many features may cost you more money than necessary, but you risk damaging the devices you need to power if you don’t get what you require.

Voltage Change:

The main purpose of a power supply is to alter voltage. The power source has a constant output regardless of the type of equipment that must utilize it. Power supply units adjust the voltage to the device’s requirements to avoid overload.

Too much power from a power source can harm a device.  However, if the power supply does not deliver sufficient voltage, the device will not perform properly. The transformer that adjusts the voltage up or down as needed is the main power supply component.

Power Conversion:

The power supply converts incoming electric power into a usable format for the device. 

Power Regulation:

The majority of electrical equipment requires regulated electricity. Because the voltage and type of electricity vary, the output of a power source is not always constant. 

The incoming voltage swings erratically, even though it does not switch on and off. Such uncontrolled power sources can produce more energy than required.

A jolt like this delivered to sensitive equipment like computers and televisions could damage the components permanently or irreversibly.

This power regulation functionality increases the cost of the device. You get to save more money in the long run because you won’t have to replace your devices due to damage from potential power surges.  

How Does A Power Supply Work? 

The most basic power supply converts voltage to DC power and back. If you need controlled power, these devices function to adjust the voltage to smooth out waves.

Read on to learn about a typical power supply component and its functions to understand better how a power supply unit works.

Components Of  A Power Supply 

Various components make up a basic power supply. These components aid the unit in stepping up or down voltage, converting power, and decreasing ripple voltages, which waste energy and cause overheating due to residual voltage variations. 


The transformer transforms the input voltage into the desired output voltage. By stepping up or down, these devices can modify the voltage. The needed DC voltage is typically much lower than the incoming AC voltage from the primary power source.


The rectifier’s job is to facilitate converting the incoming AC power to DC electricity. Half-wave, full-wave, and bridge rectifiers are the three types of rectifiers.


Power conversion from AC to DC does not necessarily eliminate waves. The filter becomes useful in this regard. The filter doesn’t smoothen the ripples entirely, but it does significantly lessen them.


A voltage regulator minimizes the ripples left by the filter, eliminating any voltage spikes or drops that could damage devices linked into the power supply.

The specialized function of the power supply unit necessitates the use of power supply components. As a result, supply components may vary from one unit to another.

Some Specifications Associated With Power Supply

In studying power supply units, you will most likely come across certain specifications. While all power supply characteristics are important, some are more so. Here are a few specifications to keep in mind:

Output Current:

This refers to the maximum current that the load can receive. A power supply unit cannot supply more current than its rated output current unless there is a malfunction, such as a short circuit at the load.

Even when transient power spikes are in the load, operating below the maximum rating permits the power supply to offer enough energy. Also, working at lower levels reduces component strain and heat loss.

Load Regulation: 

We measure the load regulation in millivolts (mV) or maximum output voltage.

The power supply’s load regulation guarantees that the circuit or system receives the required and stable voltage. The ideal load regulation is zero, which means that the supply’s output voltage remains constant regardless of the load.

Noise & Ripple: 

Noise refers to any undesired electrical interference, while ripple refers to the slight voltage variation following AC conversion to DC. Engineers usually define both concepts in single mathematical expressions. 

Overvoltage Protection: 

In some cases, output voltages can exceed their nominal values, causing damage to the load. The overvoltage safety circuit turns down the power supply when the voltage exceeds these limits.

Overload Protection:

In a short circuit or an overcurrent, overload protection is a safety mechanism that prevents damage. Like a circuit breaker in a house, Overload protection interrupts the power supply to protect the load.


Efficiency refers to the percentage of grid electricity converted to DC power. A good power supply will have at least 80% efficiency and even higher with a proper system design. An efficient system saves energy and reduces heat.


The basic role of a power supply is to convert electric power from an electric source to the right current, voltage, and frequency parameters for the load. 

Power supplies usually offer protection from short circuits or overload. An overload could destroy the supply unit or cause a fire. 

Class 2 refers to power supply devices that meet National Electric Code (NEC) regulations for wiring specifications and power restrictions to reduce the risk of shock or fire. Class 2 circuits can prevent shocks and fires by limiting power and voltage to the load.

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David Huner
David Huner
David Huner is a tech lover. After completing his graduation from the University Of Phoenix, he started gather his knowledge mostly on latest technologies that keeps his life smart and cool. Now he wants to spread his knowledge with people who loves technologies.

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