There seems to be a little bit of conflation going on?
Under national-socialism there were experiments, such as injecting unapproved and unnecessary drugs into uninformed and non-consenting subjects, exhaustion trials, and with electricity foremost plain killings, along with 'experiments' on a perhaps smaller scale. The conflation comes probably in when looking for the specific value mentioned.
The killings and deadly experiments are detailed in numerous examples, like:
— Lawrence A. Zeldman. "Neuroscience in Nazi Europe Part I: Eugenics, Human Experimentation, and Mass Murder", Can. J. Neurol. Sci., Vol 38, 2011. pp. 696–703.
Six years after it was first introduced into psychiatry in 1938, electro- convulsive therapy (ECT) became the subject of criminal human experiments in Nazi Germany. In 1944, at the Auschwitz III / Monowitz camp hospital, the Polish Jewish prisoner psychiatrist Zenon Drohocki started experimental treatments on prisoners with an ECT device that he had constructed himself. According to eyewit- nesses, Drohocki’s intention to treat mentally unstable prisoners was soon turned into something much more nefarious by SS doctors (including Josef Mengele), who used the device for deadly experiments.
— Herwig Czech, Gabor S. Ungvari, Kamila Uzarczyk, Paul Weindling, Gábor Gazdag: "Electroconvulsive Therapy in the Shadow of the Gas Chambers: Medical Innovation and Human Experimentation in Auschwitz",
Bulletin of the History of Medicine, Volume 94, Number 2, Summer 2020, pp. 244–266 doi.
Notably, this was indeed not just under the guise of therapy, but really meant as such, even if it was in most cases just the prelude for killing the patients via gas.
Peter D. and other prisoner doctors told of Fischer's involvement in a situation of psychiatric learning as well. A Polish professor of psychiatry, who had some knowledge of electroshock therapy. Then quite new, demonstrated to Fischer an apparatus he had constructed with the help of the electrical section of the Monowitz subcamp. Fischer arranged for women considered to be in need of the therapy (because they were “mad” or emotionally disturbed in some way) to be brought to the professor for shock treatments. […]
But no research or therapy escaped the Auschwitz taint. A prisoner who worked on a Birkenau hospital block later testified that “ Dr. König did electroshock experiments on women,” and added, “These women later talked about their treatment. I believe Dr. König carried out the electro shock experiments on sick women twice a week and that the women were later gassed."
In other words, the electroshock treatments could be seen as a prelude to the gas chamber, and on the basis of such testimony and other investigations the International Committee of the Red Cross in Geneva (in association with the International Tracing Service at Arolsen in West Germany) placed these“ electroshock experiments” on the list of “pseudo medical experiments" for which victims could be compensated.
— Robert Jay Lifton: "The Nazi Doctors. Medical Killing and the Psychology of Genocide", Basic Books, New York, 1986.
But the value of 30 mA seems to originate from a self-experiment. Karl Kleist was not entirely the type of fanatical nazi doctor that we expect when we deal with medical experimentation claims under national-socialism. He served as consulting psychiatrist for the army and cooperated in quite a few other ways, but also protested, for example over deteriorating conditions in mental asylums.
The idea to treat shell-shocked soldiers also with electricity did not originate with Kleist, but when the increase in customer demand started with a new war, he helped to define and refine the then current standard of care:
the method relied on 'galvanic instead of sinusoidal current' to make it safe, and Kleist wanted to see for himself how that felt.
The psychiatrist Oswald Bumke, professor at the University of Munich from 1924 on, documented his contempt for the soldiers concerned in a statement according to which he demanded the isolation of "war neurotics" from other sick people "with the same right with which one has to isolate plague patients from healthy people". But this meant nothing else than that these soldiers were declared to be inferior and dangerous elements, against whom the "most diverse methods of torture" were justified. From such a view also the so-called "Pansen", an "electrosuggestive therapy", seems comprehensible, because it was "the combination of verbal influencing of the ill soldier and simultaneous torture by unbearable pain with the help of current conducted to the skin" (p. 116). Also of interest is the following reference by the author to the method developed by Panse, which was adopted as standard treatment by Bumke and Professor Carl Schneider, among others:
"[Professor Karl] Kleist checked it in a self-experiment that became famous: He stopped the experiment already at 30 mA because of unbearable pain, although currents of up to 300 mA were regularly used with soldiers. Nevertheless, he came to the conclusion that "concerns that could be raised because of the extraordinary painfulness of the treatment […] [must] be dismissed".
There is no question that the consulting psychiatrists of the German army willingly complied with the framework set by National Socialist medicine, whose authoritative components included racial hygiene, the performance aspect, and the idea of the "healthy body of the people".
— Konrad Fuchs: Review of "Georg Berger, Die Beratenden Psychiater des deutschen Heeres 1939 bis 1945, Frankfurt a.M., Berlin, Bern, New York, Paris, Wien: Lang 1998,", Militärgeschichtliche Zeitschrift, Vol 58, No 1, 1999, doi.
This 'value' was already quite well known. Value as in 'a range of values under certain conditions and in certain combinations'. An engineer reporting on the then known values in 1933 already states in his introduction:
It is therefore of interest - especially for low-voltage installations - to know under which conditions a current flow is life-threatening. We list the most important factors:
- the current intensity,
- the duration of the current,
- the current path,
- the frequency,
- the individual installation.
As for the first point - the current intensity - it can be considered certain that a current intensity of more than 100 mA is lethal. In several cases of death by electric current, the author was able to measure and recalculate the current intensity. The result was currents of little more than 100 mA. Currents over 50 rnA resulted in unconsciousness.
It can be seen by extrapolation that a current of 30 mA is unbearable in both dry and damp skin, which is close to the limit of 50 mA, which is considered dangerous.
— Oskar Löbl: "Erdung, Nullung und Schutzschaltung nebst Erläuterungen zu den Erdungsleitsätzen", Julius Springer: Berlin, 1933. Chapter: "Der Mensch im elektrischen Stromkreis", pp. 1–7.