How To Do Risk Assessment For Lightning Protection System?

How To Do Risk Assessment For Lightning Protection System?

Sunday 1st October 2023

Every year, lightning strikes make us lose billions of pounds in property damage. This cost doesn't even factor in the downtime businesses face due to lightning-related damages. In fact, insurance companies now demand modern lightning protection systems for commercial buildings, industrial sites, government structures, and others before providing coverage.
If you own a building, knowing its susceptibility to lightning strikes is crucial. Yes, especially in an area with frequent lightning activity. Further, this awareness can help prevent property damage and save lives.

What is a Lightning Risk Assessment?

A lightning protection risk assessment evaluates the vulnerability of a building and its surroundings to lightning strikes. It also determines if an LPS is necessary to reduce the risk of damage and harm. Furthermore, this helps specify which structures on a site would benefit from additional lightning protection measures and which ones don't need extra safeguards.

Why You Should Assess Your Building's Lightning Risk

Lightning strikes lead to a significant number of insurance claims in Florida, where thunderstorms are frequent. These strikes can result in:

  • Fires
  • Electronics damage
  • Business downtime
  • Loss of life
  • Property damage

Moreover, the lightning risk assessment score for your facility influences the recommended protection measures. Factors include:

  • Areas with high human traffic
  • Facilities providing essential services
  • Regions with frequent lightning activity
  • Isolated buildings
  • Establishment storing flammable materials
  • Historical structures

What is the Minimum Height for Lightning Protection?

The minimum height for lightning protection in the UK is typically governed by the British Standard BS 6651. According to this standard, the minimum height for air termination rods should be no less than 1.5 meters above the highest point of the structure they are protecting. This ensures that lightning strikes are intercepted before they can reach the building itself, reducing the risk of damage or fire. Additionally, BS 6651 specifies that air termination rods should be spaced at intervals not exceeding 20 meters along the roof or structure. This spacing helps comprehensive coverage and efficient lightning strike interception.
It's important to note that the exact requirements for lightning protection may vary depending on:

  • The specific circumstances
  • The type of structure

For example, taller buildings or structures with unique architectural features may require a more complex lightning protection system. They would need something that takes into account their specific characteristics. In such cases, consulting with a qualified lightning protection service provider maintains compliance with safety standards.
In addition to BS 6651, other regulations and guidelines, such as from the National Annex to BS EN 62305, may also apply to lightning Protection Company in the UK. These standards further guide risk assessment, system design, and maintenance.

10 Lightning Protection Parameters You Should Know

Choice of Materials

The materials used in the lightning protection system must meet the standard requirements. They should take into account environmental factors and structural needs. Ideally, high-grade copper or copper alloys with excellent corrosion resistance are preferred. Electrical-grade aluminum with a minimum aluminum composition of 99% is acceptable. Well, it should not come into contact with copper surfaces. When joining dissimilar metals, use bimetallic connectors or fittings.

Strike Termination Devices

Moreover, these conductive components capture lightning strikes and direct them safely to the ground. Examples include:

  • Air terminals
  • Metal masts
  • Metal parts of the structure integrated into the lightning protection system

Air terminals should extend at least 10 inches above the protected area or structure. Overhead grounding conductors can be either aluminum, copper, stainless steel, or galvanized steel. The standard also specifies these devices' type, size, and placement for different roof types.

Zones of Protection

The structure's geometry determines its protection zones. Methods for determining these zones comprise

  • Air terminal placement
  • The angle method
  • The rolling sphere method


The main conductor should connect all strike termination devices within the structure, providing two or more paths to the ground. Permanent metal handrails and ladders exposed to direct lightning strikes must serve as main conductors with a minimum thickness of 1.63mm. Besides, each structure should have at least two separate down conductors. Their placement depends on factors such as:

  • The position of strike termination devices
  • Underground metallic piping systems

Conductor Fasteners and Connectors

Conductor connections should be bolted, exothermically welded, high compression, or crimp type. Connectors must withstand a pull test of 890N. Also, the fasteners used should be of the same material as the conductor or equally corrosion-resistant.

Grounding Electrodes

Down conductors should connect to one or more grounding electrodes dedicated to the lightning protection system. The choice of grounding rods (solid copper, copper-clad steel, or stainless steel) depends on soil type and corrosion. Various types of ground electrodes, including ground rods, plate electrodes, radials, and ring electrodes, are explained in the standard.

Common Bonding of Grounded System

To establish a common ground potential, all grounded metallic conductors should be interconnected with the lightning protection system. Additionally, these are:

  • Metallic water service lines
  • Gas piping
  • Underground conduits

Potential Equalization

To guarantee equal potential levels among metal conducting parts, potential equalization should occur at three levels:

  • Ground level
  • Roof level
  • Intermediate level

The standard provides details on material, size, and other requirements for equipotential bonding.

Structural Metallic Systems

If the metallic framework of the structure allows for continuous current flow, it can serve as the main conductor of the lightning protection system. Moreover, strike termination devices must be connected to the metal framework using exterior conductors with bonding, welding, brazing, drilling, or tapping methods.

Surge Protection

The lightning protection system should have the following:

  • Type I and Type II surge protection devices
  • Surge arresters
  • Surge protectors installed within the structure

Surge protection devices (SPDs) should be at the load side of incoming or branching circuits. Moreover, they might have separate requirements outlined for surge protection devices, arresters, and protectors.

How to Complete a Lightning Risk Assessment

Identify Hazards

While the primary hazard is lightning itself, inspect the entire site for potential risks that may exacerbate the dangers during a lightning strike. We are talking about examining rooftops, machinery, equipment, and steel structures.
Besides, working areas at heights should be scrutinized as these can increase the risk of lightning strikes.

Determine Who Might Be Harmed

It's not just employees who are at risk but also members of the public, especially if your construction site is located in a busy area. Involving your employees in this assessment can help pinpoint less obvious risks and devise solutions for managing and controlling hazards. It will ensure public and inexperienced workers' safety.

Evaluate Risks and Document Findings

Additionally, assess the likelihood of harm to both on-site and off-site individuals. While it may not be possible to eliminate all risks, understanding the main jeopardies associated with lightning is essential for safety management.
Regularly checking weather forecasts is a practical step to stay prepared for adverse weather conditions. Precautions like restricting access to hazardous areas or objects that can conduct electricity (due to lightning's affinity for conductive materials like metal) are also a good idea.

Implement and Communicate Emergency Plans

  • Train supervisors and employees to recognize thunder and lightning warning signs and act promptly.
  • Make sure everyone on-site is promptly informed of dangerous weather conditions and where safe shelters are located.
  • Further, clearly define when outdoor work should be suspended due to hazardous weather and when it can resume.
  • Having CPR-trained personnel on-site can be a lifesaver in emergencies.

Review PPE and Safety Equipment

Personal Protective Equipment (PPE) should be a standard requirement on construction sites, but in lighting conditions, they are vital. All employees should wear appropriate PPE and regularly review its condition to confirm it's still safe to use. Further, damaged PPE would need a replacement right away to maintain worker safety. Having extra PPE on-site is advisable in case of unexpected needs.

Continuously Review, Assess, and Update

Construction sites are dynamic environments, and conditions can change as projects progress. Regularly review and update your risk assessments to account for new changes, varying work conditions, or locations where lightning risk is more prevalent. Besides, this iterative process helps improve safety protocols and secures ongoing worker protection.

Minimize the Threat of Lightning Strikes to Your Facility

South West Lightning Protection offers thorough assessments of lightning risks and provides protection plans. These measures prevent lightning strikes from causing severe damage, injuries, or fatalities at your equipment facilities.
From the highest point of a lightning rod to the lowest tip of a ground rod or from the centre-tap of the transformer to the final branch circuit, Lightning Conductor is here to assist you with all your grounding, earthing, and bonding requirements.