An SPD is a device designed to protect electrical equipment from transient voltage spikes or surges. These spikes can be caused by lightning strikes, switching operations, or other electrical disturbances.

Single-phase electrical systems power a variety of sensitive electronics and appliances in homes, offices, and small businesses. SPDs help prevent damage to these devices caused by sudden voltage spikes, ensuring their longevity and reliability.

SPDs for single-phase systems come in several types:

• Type 2 SPDs: These are commonly installed at the main distribution board to protect against surges from indirect lightning strikes and switching operations.
• Type 3 SPDs: These provide additional protection at the point of use, such as individual sockets or equipment, and are often used in conjunction with Type 2 SPDs for comprehensive protection.

When selecting an SPD for a single-phase system, consider:

• Voltage Rating: Ensure the SPD’s voltage rating matches the system voltage (typically 230V in the UK).
• Maximum Discharge Current (Imax): This indicates the surge current capacity the SPD can safely handle.
• Response Time: Look for an SPD with a fast response time to quickly divert surges before they can damage connected equipment.

SPDs should comply with relevant standards such as BS EN 61643 and BS 7671 (Wiring Regulations). Compliance ensures that SPDs are suitable for the specific application and provide effective surge protection.