CIGRE findings debunk 10/350 waveform

Cigré 2013


In August 2013 CIGRE issued a Technical Brochure (TB 549) containing findings that fly in the teeth of the 30-year-old oft held assumption that data from Dr. K. Berger justified the use of a 10/350 µs waveform to characterize direct lightning.

Convened by the eminent Prof. Vladimir Rakov, CIGRE Workgroup C4.407's report constitutes the results of 5 years of compilation, review and analysis of all existing data on the subject of lightning parameters. The report, entitled Lightning Parameters for Engineering Applications is an update of two articles which appeared in CIGRE publications some 30 years earlier (Electra 41 and Electra 69). Those earlier articles catalogued the findings of pioneer researcher Karl Berger & colleagues. The 2013 Technical Brochure 549 can be purchased directly on the CIGRE website here.

The 2013 update is significant because the IEC 62305 lightning protection series credits those two earlier CIGRE articles as the sole source of its lightning parameters. In turn, those parameters are what has given rise to the so called "10/350 waveform" and "Class I Test". The 10/350 waveform has assumed an almost mystical status in lightning protection standards--so much so that the 62305 series assigns it the status of "the primary source of harm." (See IEC 62305-4 Annex A.)


This website has no connection to CIGRE and doesn't claim to speak for it. Since neither Karl Berger, Electra 41 nor Electra 69 ever countenanced a 10/350 waveform or Class I test, it would have been inappropriate for CIGRE's 2013 Technical Brochure to become directly involved in "uncountenanciation." CIGRE's purpose was to catalog the parameters of lightning that were reliable enough to be used for engineering applications and warn against the ones that were not. The CIGRE 2013 Report speaks for itself, containing no fewer than sixteen cautions against relying upon Berger's positive CG lightning data for engineering purposes.

Data concerning the CIGRE 2013 Technical Brochure is contained in 3 pages (of which this is the first.) Page 2 provides the 16-Cautions raw data. The final page details how CIGRE'S 2013 report deals with each of the 10/350's five lightning parameters.

All 3 CIGRE pages can be accessed through the links that follow: previous next

Kudos to Prof. Rakov and the other stellar members of Work Group C4.407 for their excellent work. To confront and align all this information was no small undertaking and marks a giant step forward in our understanding of the lightning process. It will also serve to improve lightning protection procedures and standards.

TC 81 has stated it would not permit a review of its lighting parameters until the CIGRE report was published. (Click here to go to that link.) Well, that time has arrived. Berger's Electra articles are now updated and superceded by the 2013 CIGRE report. Those of Berger's findings that have stood the test of time have been reaffirmed; those found marred by faulty equipment or procedure have been declared unreliable for engineering applications.