Introduction
Early differ) streamer emitters from franklin simple rod in one key parameter: the early streamer emission time (ΔT), which is the time it takes them to emit an upward leader. The higher the ΔT, the greater the theoretical protection radius. Some brands, seeking a competitive advantage, advertise ΔT values exceeding 60 µs (80 µs, 100 µs, or even more) to promise a larger protection zone.
But these values are contrary to the standards and mislead the end user. According to the NF C 17-102:2011 standard and international standards (UNE 21186/2118), the maximum permissible ΔT is 60 µs.
What the official standards say
- NF C 17-102:2011 : establishes the design and testing framework for PDAs. It specifies that the protection radius depends on the level of protection, the installation height, and the ΔT. Most importantly, it indicates that the maximum ΔT value for protection calculations is 60 µs.
- UNE 21186 : these Spanish standards complement NF C 17-102. They remind us that a PDA must have a ΔT strictly greater than 10 µs and that the maximum permissible value is 60 µs, even if higher results have been measured in the laboratory.
- Laboratory testing : reputable manufacturers have their products certified in high-voltage laboratories. These tests define the difference in ignition time between the PDA and a single probe and validate the ΔT value. Our catalogs clearly state that for the 60 µs models, the ΔT used in the calculations is limited to 60 µs in accordance with section 5.2.2 of NF C 17-102.
Why this 60 µs limit?
The standards do not set this threshold arbitrarily:
- Scientific reliability : beyond 60 µs, laboratory test results become unstable. Reliable manufacturers therefore limit their calculations to this value.
- Comparability : By imposing a common ceiling, all brands are evaluated on the same basis. This prevents false marketing claims and protects users from overestimated protection levels.
- Regulatory compliance : in tenders or certifications, only PDAs that meet this limit can be legally installed.
Commercial excesses: promises beyond 60 µs
Despite these clear rules, some brands advertise ignition advances of 80 µs, 100 µs, or even more, giving the impression that their ESE protects a huge area. These non-compliant values pose several problems:
- Lack of normative validation : the standards impose ΔT ≤ 60 µs, therefore a radius calculated with a ΔT of 80 µs has no regulatory basis.
- Misleading protection radii : by artificially increasing the ΔT, some sellers claim to cover radii of 200 m or more. However, standardized calculations only use the certified value (≤ 60 µs).
- Risks to installations : sizing based on an unrealistic ΔT can leave unprotected areas, increasing the risk of direct impact.
Example: comparative table
| ΔT (µs) | Compliance | Noticed |
|---|---|---|
| 10, 25, 45, 60 | Compliant with NF C 17-102 | Values validated by testing |
| > 60 (80, 100…) | Non-compliant | No normative recognition; misleading rays |
How to choose a ESE without making a mirod?
- Request certification : require a high voltage laboratory test report showing the certified ΔT value and conforming to standard NF C 17-102:2011.
- Check the stated value : if it exceeds 60 µs, avoid it; it's non-compliant. The ΔT used for calculations must be limited to 60 µs.
- Analyze brand transparency : reputable manufacturers publish protection radius tables for each ΔT and protection level (I to IV).
- Prioritize maintenance and monitoring : solutions equipped with testers (wired or remote) ensure simplified maintenance and traceability, as offered by the Ellips or Paraton@ir + Contact@ir System ranges.
LPS France 's compliant solutions
LPS Franceranges Ellips and Paraton@ir that scrupulously comply with standards:
- Available ΔT values: 10, 25, 45 and 60 µs, always less than or equal to the regulatory threshold.
- Control and monitoring : each lightning rod can be tested via a wired tester or for Paraton@ir thanks to the Contact@ir with the LPS Manager, offering real-time diagnostics.
- Compliance : the protection radii are calculated according to the standardized formula (protection level, installation height, ΔT) and presented transparently.
Conclusion
Early streamer emission (ESE) time is a crucial parameter for lightning rods with early streamer emission (ESE) devices. No recognized standard allows an ESE exceeding 60 µs. Brands advertising longer ESE times are not complying with regulations and are endangering installations. To guarantee the safety of your buildings and the conformity of your lightning protection, demand a certified ESE, request test reports, and reject promises exceeding 60 µs. LPS France, with its Ellips and Paraton@ir, is committed to this approach of transparency and reliability.
