Lightning Protection for Data Centers: Basics
A direct strike is rare, but its effects, and those of nearby strikes, reach IT equipment through the power, data and earth paths. Lightning protection is a system with several layers.
Start with a risk assessment
The IEC 62305 approach assesses risk from the structure's size, location, use and lightning frequency, and decides the protection level needed. The assessment, not habit, decides how much protection is justified.
The layers
- External protection: air terminals, down conductors and an earth termination system.
- Equipotential bonding: metallic services and the structure bonded together at the entry point.
- Surge protective devices: coordinated stages on incoming power and on data and signal lines.
- Shielding and routing: cable routes and shielding that limit induced voltage.
Surge protection coordination
SPDs are installed in stages, from the main incoming board towards sensitive equipment, so each stage limits the surge the next one sees. Their ratings and the let-through voltage must suit the system voltage and the earthing arrangement.
Common mistakes
- Treating SPDs as a substitute for external protection (or the reverse).
- A separate lightning earth that is not bonded to the main earth.
- Long SPD leads that raise the let-through voltage.
- No maintenance or testing regime.
See also earthing design.
Written by the Vision Matrix Institute editorial team. Worked examples use stated, illustrative assumptions; check them against your project data, the applicable standards and manufacturer datasheets before use.
Frequently Asked Questions
What does lightning protection consist of?
An external system (air terminals and down conductors to an earth termination), equipotential bonding, and surge protective devices on power and signal lines.
Which standard covers it?
The IEC 62305 series covers protection against lightning, including risk assessment. National standards may also apply.
Do surge protective devices replace external protection?
No. They address different paths. External protection handles a strike to the structure; SPDs protect equipment from surges entering through cables.
Why bond the lightning earth to the main earth?
So the structure and equipment rise together in potential during a strike, which limits dangerous voltage differences between them.
Want to learn this properly?
This topic is covered in depth in our Electrical Design – Data Center Specialist program.
Ask us on WhatsAppLearn to do this on a full project in the Electrical Design – Data Center Specialist program, or read the data center design guide.