Mandatory or Not ?
Following international rules, AC surge protectors are required for most of the installations. Risk assessment methods are also available to determine more accurately the need of surge protection.
The performance, selection and application of AC surge protectors are defined by standards, to ensure an efficient and secure use. National standards are based on IEC international standards.
Recommendations for SPD INSTALLATION
Section 4-443 of IEC 60364 «Protection against overvoltages of atmospheric origin or due to switching» recommends SPD application depending of the type of installation.
Protection against transient overvoltage shall be provided where the consequence caused by overvoltage affects:
a) human life, e.g. safety services, medical care facilities;
b) public services and cultural heritage, e.g. loss of public services, IT centres, museums;
c) commercial or industrial activity, e.g. hotels, banks, industries, commercial markets, farms.
For all other cases (dwellings, small apartment buildings), a risk assessment (based on Lightning density, Length of external low voltage lines and Environment factor) shall be performed in order to determine if protection against transient overvoltage is required.
SELECTION OF THE SPD
Section 5-534 of IEC 60364 «Devices for protection against overvoltages» gives the minimum performance required for SPD installed at the entrance of installation :
1 - The installation equipped with lightning rod (LPS): Recommendation : Type 1 SPD, with Lightning impulse current Iimp of 12.5 kA minimum, connected at the origin of the installation.
2 - The installation is connected to an AC network, without LPS : Recommendation : Type 2 SPD, with nominal discharge current In ≥ 5 kA, connected at the origin of the installation.