Eurolight
Have you ever noticed that some LED light fixtures have three-core power cords (with a ground wire), some have two-core cords (without a ground wire), and some don’t even need to be connected to a 220V power supply? This is determined by the light fixture’s protection level against electric shock.
According to international standards, light fixtures are classified into three classes based on their protection against electric shock: Class I, Class II, and Class III. Today, we’ll explain the differences between these three protection levels and the selection requirements.
Class I (Class I) lighting fixtures
Definition: LED lighting fixtures are protected against electric shock not only by basic insulation, but also by additional safety measures, namely connecting accessible conductive parts to a protective grounding conductor in the fixed circuit, so that accessible conductive parts will not become energized in the event of failure of basic insulation.
Features: The power cord is three-core (live wire + neutral wire + ground wire), and the ground wire must be reliably grounded. The identifier is either “⏚” or “PE”.
Identification methods: Check the power cord plug—a three-prong plug is usually Class I; check the markings—the casing is marked with a grounding symbol.
Applicable scenarios: LED Streetlights, LED floodlights, industrial LED high bay lights, outdoor LED lighting fixtures, metal-cased lighting fixtures, etc.
Class II (Class II) LED lighting fixtures
Definition: Protection against electric shock relies not only on basic insulation but also on additional safety measures, such as double insulation or reinforced insulation, but lacks grounding or installation-dependent protection.
Double insulation refers to: basic insulation (the first layer of insulation outside live parts) + supplementary insulation (backup insulation in case of basic insulation failure). Reinforced insulation refers to: a single layer of insulation system with performance equivalent to double insulation.
Characteristics: Power cord is two-core (no ground wire). The outer casing is usually made of plastic or fully insulated material. The identification symbol is a “回” shape (a square within a square).
Identification method: Two-core plug on the power cord; the outer casing is marked with a “回” shape.
Applicable scenarios: LED downlights, table lamps, floor lamps, home lighting, LED panel lights, and other places where people frequently come into contact with the light.
Class III luminaires
Definition: Class III luminaires are protected against electric shock by using a safety extra-low voltage (SELV) power supply, and ensuring that no voltage exceeding SELV is generated internally.
Safety extra-low voltage (SELV) refers to: AC effective value not exceeding 50V, and DC not exceeding 120V.
Characteristics: 220V is reduced to a safe voltage using a transformer or driver.
No grounding wire is required; the power cord is two-core.
Identification symbols are “~24V” or “SELV”.
Identification method: The nominal power supply voltage is below 50V; the luminaire label indicates “SELV” or the safety voltage value.
Applicable scenarios: Underwater lights, fountain lights, portable lights, and some low-voltage LED luminaires.
Note: Not all low-voltage luminaires are Class III luminaires. Class III luminaires require a SELV power supply system, and the luminaire must not generate a voltage exceeding SELV internally.
When purchasing lighting fixtures, the first thing to do upon receiving them is to check the electric shock protection rating and power cord type on the label. This detail can save a lot of trouble during project acceptance.
Conculsion
FAQ
Question 1: Can Class I luminaires be used if there’s no ground wire on site?
No. Class I luminaires rely on reliable grounding for protection against electric shock. Without grounding, it’s equivalent to reverting to the obsolete Class 0 luminaires, offering no effective safety guarantee. If there’s no ground wire on site, consider using Class II luminaires.
Question 2: Are all plastic-cased luminaires Class II?
Not necessarily. Class II luminaires are determined by whether their electric shock protection structure meets double or reinforced insulation requirements, not by the casing material. You can request the supplier to provide a Class II mark or test report for confirmation during procurement.
Question 3: Are 24V LED strips Class III luminaires?
The voltage limit for Class III luminaires is 50V AC/120V DC. 24V LED strips fall within this safe voltage range. However, according to relevant regulations, portable and handheld luminaires should use Class III luminaires, while portable luminaires such as table lamps and floor lamps can use either Class II or Class III luminaires.