Lightning Protection and Grounding: Six Key Requirements
There are six requirements regarding lightning protection and grounding for complete electrical assemblies: grounding system, grounding resistance, equipotential bonding, lightning protection, grounding conductors, and acceptance testing.
Industry experts emphasize strict adherence to these standards: grounding systems (TN/IT/system-specific), grounding resistance (≤4Ω standard / ≤1Ω for lightning protection), equipotential bonding (enclosure/door/frame), lightning protection (SPD surge protection), grounding conductors (cross-sectional area/material), and acceptance testing (resistance measurement).
Lightning protection and grounding measures (to safeguard personnel and equipment) must be implemented in accordance with GB 50057 and GB/T 50065.
The Six Requirements
- Grounding System: TN-S/TN-C-S (low-voltage systems), designed according to the specific system;
- Grounding Resistance: ≤4Ω (standard), ≤1Ω (lightning protection/sensitive equipment), meeting compliance standards;
- Equipotential Bonding: Enclosure/door/frame (equipotential), to prevent electric shock;
- Lightning Protection: SPD surge protection devices (lightning protection zones), properly configured;
- Grounding Conductors: Grounding busbar (copper bar cross-sectional area) and material (copper), compliant with specifications;
- Acceptance Testing: Grounding resistance measurement (acceptance check), to prevent non-compliance.
Key Points
First, resistance compliance.
Grounding resistance must meet standards (≤4Ω/≤1Ω) to ensure safety.
Second, equipotential bonding.
Reliable bonding between the enclosure and door ensures equipotentiality (preventing electric shock).
Third, SPD configuration.
Reasonable configuration of SPDs (surge protection) based on lightning protection zones.
Fourth, acceptance testing.
Conduct grounding measurements (to ensure compliance) and document the test results.
Pitfalls to Avoid
First, “excessive resistance.”
Grounding resistance exceeding limits poses a risk of electric shock; corrective action is required to meet standards.
Second, “missing equipotential bonding.”
Failure to bond doors or frames creates an electric shock risk;
proper connections must be established. Third, “missing SPDs.”
The absence of Surge Protective Devices (SPDs) in lightning protection zones risks damage from lightning strikes;
SPDs must be installed.
Trends and Reminders
Lightning protection and grounding are moving towards greater standardization, characterized by graded lightning protection (SPD-based tiered protection) and online monitoring of grounding status.
Designers are advised to adhere to the “six key requirements,” ensure resistance compliance, and conduct acceptance testing.
Proper lightning protection and grounding ensure the safety of both equipment and personnel.
