LED Power selection Information

NEC Class 2 and IEC Class II are concerned with safety, they address different aspects: NEC Class 2 limits power output to prevent fire and shock, whereas IEC Class II emphasizes construction standards for shock protection through insulation. When selecting power supplies, understanding these differences is crucial for compliance and safety in specific applications and regions.

The terms NEC Class 2 and IEC Class II refer to classifications from different regulatory bodies and standards that address different aspects of electrical safety and performance for power supplies and electrical equipment. Understanding the distinction between the two can help in selecting the appropriate power supply for specific applications, ensuring compliance with safety regulations and operational reliability.

NEC Class 2

• Regulatory Body: National Electrical Code (NEC) in the United States.
• Focus: Safety limitations on power output to prevent fire and electric shock. Class 2 specifies limits on the voltage and current output by a power supply. Specifically, it limits power supplies to:
  • 30 Volts AC or 60 Volts DC maximum
  • 100VA (Volt-Ampere) or less
  • Limited energy to reduce risks of fire and electric shock
• Applications: Common in low-voltage applications such as LED lighting, control circuits, and other situations where reducing the risk of fire and electric shock is a priority.
• Marking: Products meeting Class 2 standards are often marked as “Class 2 Power Supply.”

IEC Class II

• Regulatory Body: International Electrotechnical Commission (IEC).
• Focus: Protection against electric shock. Class II equipment is designed with double insulation or reinforced insulation without relying on an earth connection (grounding) for safety.
• Applications: Includes a wide range of electrical devices not limited by power output but by the necessity for enhanced protection against electric shock. This can include power supplies, household appliances, and office equipment.
• Marking: Class II equipment is marked with a double square symbol (⧈).

Key Differences

1. Scope of Regulation:
   • NEC Class 2 focuses on limiting the power output to reduce risks of fire and electric shock, specifically in low-voltage applications.
   • IEC Class II focuses on the construction and insulation requirements to protect against electric shock, regardless of the voltage or power output.
2. Safety Mechanism:
   • NEC Class 2 achieves safety through power limitation.
   • IEC Class II achieves safety through double or reinforced insulation, making grounding unnecessary for protection against electric shock.
3. Regulatory Region:
   • NEC is primarily used and recognized in the United States.
   • IEC standards are internationally recognized and used in many countries around the world.
4. Application and Use:
   • NEC Class 2 is specifically relevant for certain types of low-voltage equipment and wiring.
   • IEC Class II applies more broadly to a variety of electrical equipment, focusing on insulation safety rather than power output.

Here is an example of a listing, very low W (watts), it’s 24v but won’t meet amp demand. Look at the classification on the lower picture, it says class 2, not 2 square picture.

Checking with AI :
I asked about a design to build it myself, a power supply. What would be some considerations. This is not out of the normal operating procedures, Millions of power supplies are trashed every year, lets see if we can re-use one

The engineering requirements for a power supply for LED strip lights are important for ensuring the efficient, safe, and reliable operation of the lighting system. Here are the key factors to consider:

1. Voltage Match: LED strips typically operate on low voltage, usually 12V or 24V DC. The power supply must match the voltage requirement of the LED strip to avoid damaging the LEDs.
2. Current Capacity (Amperage): The power supply must be able to provide sufficient current to power the total length of LED strip being used. The current requirement can be calculated by multiplying the current draw per meter (or foot) of the LED strip by the total length of the strip.
3. Power (Wattage): The power supply’s wattage rating must be adequate to supply the total wattage consumed by the LED strip. It’s advisable to choose a power supply that has a higher wattage rating than the total wattage of the LED strip to prevent overloading. A good rule of thumb is to add a 20% buffer to the total wattage calculation to ensure the power supply is not operating at its maximum capacity, which can lead to overheating and reduced lifespan.
4. Quality and Reliability: Choose a power supply from a reputable manufacturer that meets safety and quality standards. Look for certifications such as UL, CE, or RoHS that indicate compliance with safety and environmental regulations.
5. Efficiency: High-efficiency power supplies generate less heat and have lower operating costs. Look for a power supply with an efficiency rating of 80% or higher.
6. Protection Features: Overvoltage, overcurrent, and short circuit protection are important features to protect the LED strip and the power supply itself from damage. Thermal protection is also beneficial to shut down the power supply if it overheats.
7. Environmental Conditions: Consider the operating environment of the LED strip. If the power supply is to be used outdoors or in a damp environment, it should have an appropriate ingress protection (IP) rating to withstand moisture and dust.
8. Physical Size and Installation Requirements: Make sure the physical dimensions of the power supply are suitable for the intended installation location. Also, consider the need for ventilation around the power supply to dissipate heat.
9. Dimming Capability: If dimming of the LED strip is desired, ensure the power supply is compatible with the dimming method being used (e.g., PWM, 0-10V, or DALI).
10. Connectivity: The power supply should have the necessary connectors or terminals for easy and secure connection to both the power source (AC mains) and the LED strip (DC output).

Selecting the right power supply involves careful consideration of these factors to ensure the LED strip lights perform well and have a long service life.