This practical guide shows you how to complete a signed, QR-verified Lightning Protection System (LPS) & SPD Engineering Audit certificate in OhmCert Module #15 and how to troubleshoot non-compliant readings on site.

1. Step-by-Step OhmCert UI Workflow

  1. Open Module #15: Navigate to Lightning Protection System (LPS) & SPD Engineering Audit from the Dashboard.
  2. Load a 1-Click Standard Annex Preset: Open the blue Standard Annex banner at the top and click a preset (such as "LPS Class II Industrial / Data Center (40x25x12 m, Ring Earth)") to populate target limits automatically.
  3. Enter Your Field Measurements: Fill in the measured inputs (LPS Protection Level (IEC 62305-3), Structure Length L, Structure Width W, Structure Height H, Ground Flash Density Ng, Air-Termination Mast Height h above Roof, Installed Number of Down Conductors, Current Partitioning Factor kc (IEC 62305-3 Table C.1), Separation Insulation Material km (IEC 62305-3 Table 6), Length l along Down Conductor from Equipotential Bond, Actual Separation Distance s_actual to Metal/Cables, LPS Earth Termination Resistance R_A, Soil Resistivity rho (for IEC 62305-3 Fig. 2 l1 check), Down Conductor & Bonding Continuity, SPD Nameplate Voltage Protection Level Up, SPD Total Connecting Lead Length (L + PE)). Blank inputs stay neutral PENDING.
  4. Complete the 20-Point Checklist: Grade each item, attach photos if needed, and export the SHA-256 signed PDF certificate.

2. Worked Numerical Field Case Study

Scenario: LPS Class II Industrial / Data Center (40x25x12 m, Ring Earth) (IEC 62305 Class II) — LPL II (r=30m, 10x10m mesh, 10m down-conductor spacing, ki=0.06, kc=0.44, km=0.5 concrete)..

  • LPS Protection Level (IEC 62305-3): Class II
  • Structure Length L: 40 m
  • Structure Width W: 25 m
  • Structure Height H: 12 m
  • Ground Flash Density Ng: 2.5 1/km2/yr
  • Air-Termination Mast Height h above Roof: 3 m
  • Installed Number of Down Conductors: 14
  • Current Partitioning Factor kc (IEC 62305-3 Table C.1): 3+ Down Conductors / Ring Earth (kc = 0.44)
  • Separation Insulation Material km (IEC 62305-3 Table 6): Concrete / Brick / Masonry (km = 0.5)
  • Length l along Down Conductor from Equipotential Bond: 12 m
  • Actual Separation Distance s_actual to Metal/Cables: 0.85 m
  • LPS Earth Termination Resistance R_A: 4.2 Ohm
  • Soil Resistivity rho (for IEC 62305-3 Fig. 2 l1 check): 250 Ohm-m
  • Down Conductor & Bonding Continuity: 0.08 Ohm
  • SPD Nameplate Voltage Protection Level Up: 1.5 kV
  • SPD Total Connecting Lead Length (L + PE): 0.35 m

3. Engineering Troubleshooting: Corrective Actions When a Reading Fails

  1. Re-wire SPD connections using V-connection (Kelvin) layout or shorten L+PE lead total below 0.50 m so U_p/f stays <= 0.8 * U_w.
  2. Increase physical distance between LPS conductors and rooftop metal plant, or install additional down-conductors to lower the current-sharing factor k_c.
  3. Extend Type B ring earth electrode or add deep rods where RA > 10 Ohm or l_1 is below the IEC 62305-3 soil resistivity curve.

→ Try This Worked Example Live in Module #15 (Lightning Protection (LPS))