In the "Hasse 10/350 waveform Chart" shown elsewhere you can see the two parameters of the 10/350 signature highlighted in pink: T1 = 10μs and T2 = 350μs. But the "10/350 waveform" has always been a misnomer. Look again at Hasse's Chart and you will see it includes three other parameters (highlighted in yellow): Peak current = 200 kA; Charge (Q) = 100 coulombs; and W/R = 10MJ / Ω.
For over 30 years the "10/350 waveform" was always a package deal. It always included those 5 parameters. And the value of peak current (kA) was always twice the value of the charge (coulombs). Why? Maybe because all 5 of those parameters were needed to lock-in the use of the spark gap surge protectors? The reader can decide. Meanwhile, the CIGRE 2013 report lends no credibility to these parameters or any such relationship between parameters.
Below you have Table from the most recent IEC International Lightning Standard (IEC 62305-1). This is the foundation on which the entire IEC lightning protection standard is built. Does anything look familiar? (Roll your mouse over it to see where the key parameters originate.)
CIGRE's 2013 Technical Brochure 549 has made it clear that CIGRE can no longer be blamed for the highlighted parameters in the above chart, including the 10/350 waveform itself. Do you recall the fable of the lamb and the wolf? Under the wool of the IEC 62305 lightning protection standards you will find only the hide and claws of Dr. Peter Hasse.
The time has come for the international lightning protection community to confront that fact and delete the mandatory use of those parameters from standards.