The 10/350 broken promises

In 1995, when IEC 61312-1 introduced the 10/350 waveform into international standards, two promises were made. These promises have been repeated in every lightning protection standard since then up to and including IEC 62305 series. The promises are:


PROMISE #1: The lightning current parameters...are based on the results of CIGRE in Electra 41 (1975) and 69 (1980).

In fact, as has been shown elsewhere on this web this was a false promise. The data never came from CIGRE.

PROMISE #2: If we accept the values of current, charge, energy and duration proposed by the standard (Lightning Protection Level 1) then "approximately 99% of all flashes are to be covered." This promises a 99% lightning protection success rate if we only agree to suffer the trouble and complexity of spark gaps and Class I tests.

This is another false promise. As is shown elsewhere on this web, failure rates considerably higher than this promise have been observed in sites protected according to standards based on these 10/350 "Lightning Protection Level" parameters.

IEC 62305-1 tells us the entire 62305 series hangs or falls on its system of lightning protection levels. Let's say we agree with the validity of this statement.

But what if lightning protection installations based on the 10/350 waveform can have failure rates 500% to 700% higher than we were promised?

Where, then, does that leave the 62305 standard?

Dear reader, please answer this question: Where does this leave the 62305 standard?


Here are the original promises from IEC 61312-1-1995 Annex A: