The client engaged Osiris Group to evaluate the existing lightning protection system at an Amazon warehouse site where a major solar photovoltaic (PV) installation had recently been added.

Amazon’s warehouses use highly sensitive robotic logistics systems, making them particularly vulnerable to overvoltages caused by lightning strikes or surge events.
The new PV array introduced additional cable routes and connection points — creating new potential risks.

The challenge was to assess the integrity of the lightning protection system, the building fabric, and the PV installation without disrupting operations, while ensuring compliance with current standards.

We conducted a comprehensive risk assessment and technical survey of the site, covering:

• Existing Lightning Protection System (LPS) integrity and compliance
• Building fabrication and its impact on earthing and surge pathways
• PV cable routing and penetration points
• Surge protection measures in place and missing

Our investigation revealed:

• Potential weak points where equipotential bonding at the rooftop level was insufficient to protect against surge pathways entering the building’s internal zones.
• Inadequate external cable routing from the PV system to the ground-level inverters.

Our recommendations included:

• Re-routing all PV cabling externally to avoid bringing lightning currents directly into the internal zones of the building.
• Installation of coordinated surge protection devices (SPDs) at critical points within the PV electrical system, rather than relying solely on a main incomer SPD.