Choosing the right kA is a systematic process that involves risk assessment, installation location, and regulatory compliance.
The installation location of the surge protector (SPD) in your electrical system directly determines the required kA nominal value. This is typically categorized by “Type”:
Type 1 (Level 1 Protection): Installed in the main distribution cabinet, where power enters the building. It must be able to withstand the largest surges, such as direct lightning strikes. 40KA SPDs, 60KA surge protectors, or even 100KA SPDs are commonly used here.
Type 2 (Level 2 Protection): Installed in the distribution box to protect downstream equipment. This is the most common type of whole-building protection. 40KA Type 2 SPDs are a popular and robust choice in many applications.
Type 3 (Level 3 Protection): Installed at the equipment end to provide fine protection for the most sensitive equipment, such as servers and medical devices. They are typically used in conjunction with the first two types of SPDs, with lower kA requirements.
Compliance with local electrical codes is crucial. For example, in China, GB 50057 “Code for Design of Lightning Protection of Buildings” and GB 50343 “Technical Code for Lightning Protection of Electronic Information Systems in Buildings” must be followed. These standards typically specify the minimum kA requirements for SPDs at different installation points based on factors such as building type and thunderstorm day zoning.
High-risk/Main Inlet: Select a high-kA Type 1 SPD, such as a 60KA or 100KA SPD.
Medium-risk/Distribution Box: Select a reliable Type 2 SPD, such as a 25KA or 40KA Type 2 SPD.
Fine Protection: Select a Type 3 SPD for specific equipment.
Suitable for small homes and apartments in low-risk areas, or as a level 3 protection after Type 2.
The 20KA surge protector can be used for secondary protection in ordinary urban residences, small shops, and offices, making it a cost-effective choice.
The 40KA SPD is suitable for the secondary protection standard configuration of most commercial buildings, medium-sized factories, and high-rise residential buildings in cities, providing excellent protection.
Applicable scenarios: Main distribution boxes (secondary or combined type) in buildings in areas with moderate to high lightning risk, or industrial environments.
The 80KA surge protector is used in the main distribution boxes of high-risk areas, rural areas, and detached buildings, providing stronger current discharge capacity.
100KA SPD is used for the main entrances of large industrial facilities, hospitals, data centers, or as Type 1 protection for important buildings.
Used for protection of the main entrances to thunderstorm areas, critical infrastructure (such as airports and chemical plants), and communication base stations.
Voltage Protection Level (Up): This parameter reflects the actual voltage the equipment will experience more directly than the kA value. When selecting an SPD, ensure its Up value is lower than the withstand voltage rating of the protected equipment.
Backup Circuit Breaker: Ensure the capacity of the circuit breaker or fuse used with the SPD is matched to safely disconnect the circuit in the event of SPD failure.
Module Status Indicator: Select an SPD with remote signaling or visual alarms (such as window color changes) to facilitate quick status assessment by maintenance personnel.
Why isn’t higher kA always better?
An excessively high kA value may lead to a correspondingly high residual voltage (protection level) in the SPD, resulting in insufficient protection for delicate equipment. Furthermore, high kASPD values are more expensive and may be larger. The principle of “sufficient with a margin” should be followed.
What’s the difference between 10KA Surge Protector and a 40KA Type 2 SPD?
The main difference lies in the current discharge capacity. A 40KA Type 2 SPD can absorb and discharge surge currents up to 4 times greater than a 10KA surge protector, thus providing more reliable protection for larger, more critical buildings or equipment, and typically has a longer service life.
Is the kA rating of an SPD for a single mode or the sum of all phases?
KA typically refers to single-mode (single-pole) operation. For example, a single-phase SPD nominally rated at 40kA means that each of its L and N poles can handle a surge of 40kA. A three-phase 40kA SPD means that each of its L1, L2, L3, and N poles can handle 40kA.
How can I determine if my SPD has failed?
Most modern SPDs are equipped with visual indicator windows (usually green for normal operation and red/black for failure) or remote alarm contacts. Regularly checking these indicators is a critical part of maintenance.
Can I increase the kA capacity by connecting a new SPD in parallel with the old one?
This is strongly discouraged. Due to slight differences in device characteristics, they cannot evenly distribute surge current, which may cause one of them to fail first, creating a safety hazard. The correct approach is to replace it with a new SPD with a higher kA capacity.
Optimized by Seraphinite Accelerator
