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LVD (Low Voltage Directive)

The Low Voltage Directive (LVD) is an EU regulatory framework ensuring that electrical equipment within certain voltage limits provides a high level of protection for European citizens.

The Low Voltage Directive (LVD), officially Directive 2014/35/EU, is one of the core legislative pillars of the European Union’s CE marking process for electronic and electrical products. Despite its name, the LVD does not apply exclusively to what electronics engineers typically consider “low voltage” (e.g., 3.3V or 5V logic).

Instead, the LVD applies to electrical equipment designed for use with a voltage rating of between:

  • 50 and 1000 V for alternating current (AC)
  • 75 and 1500 V for direct current (DC)

If a product falls within these voltage envelopes (which covers almost all mains-powered devices, industrial chargers, and high-voltage DC-DC converters), it must comply with the LVD to be legally commercialized in the European Economic Area (EEA).

Scope and Intersection with the RED

A critical, often misunderstood regulatory nuance is the interaction between the LVD and the Radio Equipment Directive (RED, 2014/53/EU).

If a product contains a radio transmitter or receiver (e.g., Wi-Fi, Bluetooth, LoRa) and falls under the RED, the LVD voltage limits do not apply.

Under Article 3.1(a) of the RED, the safety objectives of the LVD are mandated for all radio equipment, regardless of its voltage limit. Even a battery-powered 3.3V Bluetooth Low Energy (BLE) sensor beacon must be tested against LVD safety standards if it is to achieve CE marking under the RED.

Key Safety Standard: EN IEC 62368-1

The most pervasive harmonized standard used to demonstrate conformity with the LVD for IT and audio/video equipment is EN IEC 62368-1 (which replaced the legacy EN 60950-1 and EN 60065).

Unlike prescriptive legacy standards, EN 62368-1 is a Hazard-Based Safety Engineering (HBSE) standard. It requires designers to:

  1. Identify energy sources in the product (electrical, thermal, kinetic, radiated).
  2. Classify the energy sources based on their potential to cause injury (Class 1, 2, or 3).
  3. Identify the user attempting to access the equipment (Ordinary, Instructed, or Skilled).
  4. Design and implement appropriate safeguards (equipment safeguards, basic safeguards, supplementary safeguards) to prevent energy transfer to the user.

Key Hardware Design Concepts for LVD Compliance

Compliance with the LVD dictates fundamental mechanical and PCB architectural constraints:

  • Creepage and Clearance:
    • Clearance: The shortest distance through the air between two conductive parts. It mitigates the risk of dielectric breakdown (arcing) due to transient overvoltages.
    • Creepage: The shortest path along the surface of a solid insulating material between two conductive parts. It mitigates the risk of tracking (surface breakdown) due to environmental contamination (Pollution Degree). Designers must physically space high-voltage primary circuits (like 230V AC mains) away from low-voltage secondary circuits (SELV - Safety Extra Low Voltage) using specified minimum distances, often requiring physical slots routed into the PCB.
  • Isolation and Dielectric Withstand (Hi-Pot): Transformers, optocouplers, and digital isolators crossing the safety barrier must withstand high-voltage injection tests (e.g., 1500 Vrms or 3000 Vrms for 1 minute) without insulation breakdown.
  • Flammability: PCB materials (typically FR-4) and plastic enclosures must carry specific UL 94 flammability ratings (e.g., V-0) to ensure they self-extinguish and do not propagate fire in a single-fault condition.
  • Earth Bonding: Exposed metal chassis parts accessible to an ordinary user must be robustly bonded to the protective earth (PE) pin of the mains plug to ensure fault currents trip the circuit breaker rather than passing through a human operator.

The Inovasense Approach to LVD

Safety cannot be retrofitted. At Inovasense, electrical safety and HBSE principles are embedded directly into the schematic capture and component selection phases of our V-Model.

During PCB layout, we establish rigorous, rule-based design constraints (DRCs) within Altium Designer to automatically enforce creepage and clearance boundaries across primary, secondary, and protective earth domains. By treating the LVD as a core architectural input rather than a secondary compliance checkbox, we deliver hardware architectures that pass external safety evaluations on the first attempt, preventing months of costly redesigns.

Related Terms

CE-MARKING EMC RED