What is the difference between Class 2 and SELV

Introduction

In electrical engineering, two important terms used to describe safety measures are Class 2 and Separated Extra-Low Voltage (SELV). These terms refer to different types of low-voltage systems commonly found in various applications. Understanding the difference between Class 2 and SELV is crucial for ensuring electrical safety and compliance with relevant standards.

Class 2

Class 2 refers to a type of power supply or equipment that meets specific safety requirements outlined by the National Electrical Code (NEC) in the United States. The primary emphasis of Class 2 is to limit the output voltage and current levels to prevent electric shock and potential fire hazards. Class 2 circuits operate at a maximum of 30 volts DC or 60 volts AC. They are designed to provide sufficient protection against direct contact with live parts.

SELV

SELV stands for Separated Extra-Low Voltage. It is an international safety standard defined by the International Electrotechnical Commission (IEC). Unlike Class 2, SELV focuses on providing further protection against electrical shock by isolating the low-voltage system from hazardous voltage sources. SELV systems operate at voltages not exceeding 42.4 volts peak AC or 60 volts DC and have specific requirements for installation and insulation.

Differences and Applications

The main difference between Class 2 and SELV lies in their safety focus. While both aim to prevent electrical shocks, Class 2 concentrates more on limiting output voltage and current, whereas SELV emphasizes physical isolation from hazardous voltage sources. Class 2 systems are commonly used in applications such as small appliances, lighting fixtures, and thermostats. SELV systems are often found in medical equipment, transportation systems, and data communication installations, where enhanced protection is necessary.

It's important to note that compliance with electrical safety standards varies across different countries and regions. The classification of a specific system as Class 2 or SELV depends on the applicable regulations and guidelines in that particular jurisdiction. It is essential for manufacturers, installers, and users to ensure adherence to the relevant standards to mitigate potential electrical hazards and maintain overall safety.