Graham. wrote:

so is 1000V. (so is 1500V. if it's DC)
::::::::::
::::::::::
so is 231V.
so is 230V.
So is 229V.
well-known series
So is 51V.
So is 50V.

You could argue that the rest isn't, because it is ELV. Depends on
context, obviously.

--

Roger Hayter