Recommended surge protection modules for distribution boxes

For distribution boxes, Type 1 SPDs are recommended at the main entry, Type 2 SPDs for sub-distribution boards, and Type 3 SPDs for sensitive terminal equipment, with modular combined devices available for comprehensive protection.

Surge Protection Types and Applications

Type 1 SPDs (Primary Protection)Installed at the main distribution board or power entry point to protect the entire electrical system from external surges, such as lightning strikes. Capable of handling high-energy surges, typically 40 kA or more for an 8/20 µs waveform. Connected to the building's grounding system for robust surge diversion.

Ideal for first-level protection to prevent surges from entering the building. Type 2 SPDs (Distribution Board Level Protection)Installed within distribution boards to protect downstream circuits and equipment. Handles medium-intensity surges, usually 10–40 kA (8/20 µs waveform).

Provides second-level protection against internal surges caused by switching operations or motor startups. Often installed next to circuit breakers or integrated into the distribution board for easy maintenance. Type 3 SPDs (Terminal Equipment Protection)Protects sensitive devices such as computers, TVs, or control systems from residual surges not fully mitigated by Type 1 or Type 2 SPDs.

Ensures even small voltage spikes are eliminated, safeguarding high-performance electronics.

SP

D ConfigurationsSingle-phase systems: Use 1+NPE SPDs to protect line, neutral, and protective earth conductors for comprehensive protection. Single-pole (1P) SPDs only protect the line conductor and leave potential surge paths through neutral or ground. Three-phase systems: Use 3+NPE SPDs to protect all phase conductors, neutral, and earth.

Three-pole SP

Ds without neutral protection are suitable only for specific motor loads or delta-connected systems.

Modular Combined Solutions

Combined Type 1+2+3 modules (e.g., MUA-100) provide full protection from the building entrance to terminal devices. Modular design allows quick installation and maintenance, with optional fuse modules to protect outgoing circuits. Recommended for new buildings or extensions with high-power consumers such as heat pumps, wallboxes, or PV systems.

Installation Tips

Install SP

Ds as close as possible to the service entrance for maximum effectiveness, ideally with conductor lengths under 6 inches. Ensure compatibility with the grounding system (TN, TT, or IT) and match the voltage protection level (Up) to the sensitivity of connected equipment. Follow standards such as IEC 62305 and DIN VDE 0100-443/534 for proper selection and installation.

By combining Type 1 SPDs at the main entry, Type 2 SPDs in sub-distribution boards, and Type 3 SPDs for sensitive equipment, or using modular combined devices, you can achieve comprehensive surge protection for residential, commercial, or industrial electrical systems.