Will the volt, ampere, ohm or other electrical units change on May 20th, 2019? When  watching a video by Veritasium about the SI units redefinition (5:29), a claim that the volt and unit of resistance (presumably the ohm) will change by about 1 part in 10 million caught my attention:

[...] I should point out that a volt will actually change by about 1 part in 10 million, and resistance will change by a little bit less than that. And that's because back in 1990, the electrical metrologists decided to stop updating their value of, effectively, plancks constant, and just keep the one they had in 1990. And there was a benefit to that: they didn't have to update their definitions or their instruments. [...] Well, now the electrical metrologists will have to change. But, that's a very tiny change for a very tiny number of people.

Apparently, the reason is that on 20 May, 2019, redefinitions of SI base units are scheduled to come into force. The kilogram will be redefined using the Planck constant, which, presumably, means that any change in value from the previous definition (the International Prototype of the Kilogram) would affect derived units depending on it, including the volt, ohm, farad, henry, siemens, tesla and (formerly) ampere. 



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*Will the volt or ohm change, as Veritasium seemingly claims?


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*Are any other electrical units (listed above) affected?

*If so, exactly how much will they have changed after the redefinition?


 A: The redefinition redefines units with exact values for $h,\,e,\,k_B,\,N_A$. The old definitions of metres and seconds are retained, so specifying $h$ redefines the kilogram. The ampere (1 coulomb per second) will change because specifying $e$ redefines the coulomb. (The old definition takes the ampere as fundamental, specifying $\mu_0$ as $4\pi\times 10^{-7}$ in SI units.) The volt changes because $eV$ is an $e$-dependent force, which when multiplied by a metre-second gives the units of $h$. Since the volt change depends on $h$ s well as $e$, you needn't count powers of $e$ to realise the ohm will slightly change (but since $1\Omega=1\text{Js}/\text{C}^2$, $e$ matters here too). By the same logic, the farad (second per ohm) changes, as do the Henry (ohm second), siemens (1/ohm) and tesla ($\text{Vs}/\text{m}^2$).
A: Yes, the volt really will change. 
If you have a Really Good Voltmeter that’s capable of one part in 10-million accuracy, you’re already used to the idea that you have to get it periodically calibrated against a chain of standards leading back to some national standards body. 
The next time you go in for that calibration on your RGV after May 20, the calibration will change. 
Few people actually have such devices. People who make such precise measurements generally know about these issues and have been making plans to deal with the changes. 
