Lightning protection relies on a variety of technical solutions, but the ) lightning rod ESE early streamer emission stands out as one of the most effective. Therefore, understanding how it works is essential for any facility safety professional.
Thus, this article presents the fundamental principles of the PDA, its advantages compared to the classic Franklin lightning rod, and the requirements of the IEC 62305 and NF C 17-102:2011 which govern its installation internationally.
What is an early streamer emission (ESE) lightning rod?
The ESE is a rooftop lightning rod designed to attract and channel lightning strikes to the ground in a controlled manner. It represents a significant technological advancement compared to the traditional Franklin rod.
Unlike a conventional lightning rod, the PDA incorporates an early initiation mechanism that allows it to initiate an upward leader before any other lightning point of the same geometry in its vicinity. As a result, it captures lightning over a much wider area.
- Franklin rod : passive protection, radius limited by the fictitious sphere method (IEC 62305-3)
- PDA (ESE) : early initiation thanks to the ΔT parameter, greater protection radius Rp
- Key difference : the PDA often replaces 8 to 12 Franklin rods for the same area to be protected
⚠️ Important point : the PDA is a lightning detector rooftop surge protector (SPD), which is a surge protection device installed in electrical panels.
The parameter ΔT: the ignition advance
The operation of the PDA is based on a precise physical concept: the priming advance, quantified by the parameter ΔT (delta T), expressed in microseconds (µs).
In practical terms, ΔT represents the time lead with which the ESE emits its upward tracer compared to a reference Franklin rod under the same conditions. The higher the ΔT, the larger the protection zone.
- ΔT = 10 µs → advance in distance ΔL = 10 m
- ΔT = 25 µs → advance in distance ΔL = 25 m
- ΔT = 45 µs → advance in distance ΔL = 45 m
- ΔT = 60 µs → advance in distance ΔL = 60 m
Therefore, the formula for the protection radius Rp incorporates this lead: Rp = √(2 × R × h − h²) + ΔL (for h ≤ 5 m). Thus, a PDA with ΔT = 60 µs installed at a height of 5 m on an industrial building offers a protection radius exceeding 80 m — enough to cover the majority of sites with a single mast.
This ΔT is measured and certified in a high-voltage laboratory according to the protocol defined in Annex A of standard NF C 17-102. In addition, each ESE placed on the market must be accompanied by a test report issued by an accredited third-party laboratory.
The regulatory framework: NF C 17-102 and IEC 62305
Internationally, lightning protection is governed by the IEC 62305, which defines four levels of protection (LPL I to IV). Power supply devices (PSDs), on the other hand, are specifically covered by the NF C 17-102:2011, adopted in many countries (Spain, Portugal, Belgium, North Africa, the Middle East, and many others).
In France — and more broadly in French-speaking countries — these two standards coexist without replacing each other, because they do not cover the same technologies :
- IEC 62305-2 : Risk analysis to determine if protection is necessary and at what level (uses ground lightning density Nsg)
- IEC 62305-3 : Physical protection of structures via Franklin rods and mesh systems — does not cover PDAs
- NF C 17-102:2011 : exclusively dedicated to PDA/ESE, with Rp calculation including ΔL — does not cover Franklin or meshed
Thus, choosing a ESE does not mean abandoning IEC 62305 — it means supplementing the IEC 62305-2 risk analysis with the technology defined in NF C 17-102. The two standards apply sequentially, not in opposition.
For high-risk sites (ATEX sites, wind farms, data centers), it is now possible to refine the IEC 62305-2 analysis using Nsg (lightning intensity measured in clouds) provided by Strike Radar. This localized historical data—more precise than the Nsg tables in the standards—allows for an objective justification of the protection level chosen during regulatory audits.
The concrete advantages of the ESE in the field
The decisive argument in favor of the PDA is economic: a single PDA replaces 8 to 12 Franklin rods for a large area. In short, this reduction in the number of collection points translates into significant savings across the entire project.
For example, for a 5,000 m² warehouse, a Franklin Level I system would require a dozen rods and as many downpipes. In contrast, a single ESE with a ΔT of 60 µs can cover the entire structure with only two downpipes.
The benefits are cumulative on several levels:
- 2 runs minimum (compared to 7 to 12 for a Franklin on large surfaces)
- 2 grounding points (reduced excavation work)
- A single collection point : minimal aesthetic and architectural impact
- Faster installation : simplified construction site, reduced labor costs
- Suitable for existing buildings where adding multiple downpipes would be complex
In addition, typical applications include industrial buildings and warehouses, listed sites, healthcare facilities, telecommunications facilities, and outdoor storage areas.
Installation requirements according to NF C 17-102
First, the tip of the PDA must be positioned at least 2 m above the highest point of the structure to be protected. Second, the down conductors must have a minimum cross-section of 50 mm² in copper, 70 mm² in aluminum, 50 mm² in hot-dip galvanized steel or 50 mm² in stainless steel.
Regarding grounding connections, the individual resistance of each connection must be ≤ 10 Ω. Furthermore, the two ground connections should be interconnected where possible to ensure optimal equipotentiality.
These requirements apply in all countries that have adopted NF C 17-102 or equivalent standards. Therefore, installers operating in Europe, North Africa, the Middle East, or South America will find the same fundamental principles.
Mandatory maintenance: what the standard says
The NF C 17-102 standard mandates a rigorous maintenance program. Consequently, operators must plan three distinct types of checks:
- Annual visual inspection : integrity of the PDA, condition of conductors, connections, visible ground connections
- Complete inspection every 2 years : earth resistance measurement (≤ 10 Ω), continuity test, PDA verification according to manufacturer's protocol
- Verification after each detected impact : immediate inspection, continuity test, replacement if necessary
Furthermore, a maintenance log must be kept up to date, recording all inspections, measurements, and interventions. However, manually managing these records can prove complex for managers of multi-site facilities.
This is precisely why digital solutions like LPS Manager make it possible to centralize these files, automate alerts and generate compliance reports in just a few clicks.
ESE lightning rods from LPS France
LPS France offers two lines of early streamer emission (ESE) lightning rods, designed to meet the requirements of international markets:
- Paraton@ir : IoT-connected PDA, compatible with the Contact@ir for real-time remote monitoring
- Ellips : High-performance PDA with the same dimensions as the Paraton@ir, designed for architectural constraints and aesthetic integration.
Ultimately, the choice between these two product lines depends on the specific needs of the project: the desired level of connectivity, architectural constraints, and available maintenance budget. In all cases, both products are certified according to NF C 17-102:2011 with documented ΔT values.
Conclusion
The early streamer emission (ESE) lightning rod represents the most effective solution for protecting large structures against lightning, combining an extended protection radius thanks to the ΔT parameter with simplified installation and reduced maintenance costs.
Ultimately, compliance with IEC 62305 and NF C 17-102:2011 guarantees not only the safety of people and property, but also the traceability required during regulatory audits. For sites requiring in-depth risk analysis, Strike Radar complements the IEC 62305-2 approach. To learn more, explore the full range of LPS France or contact our experts for a personalized assessment.
Once your installation is compliant with IEC 62305, manage and plan its maintenance with LPS Manager, the SaaS platform dedicated to lightning protection professionals.
