[paleface]

> Low Voltage is a very specific term […]

It’s not a very specific term, at all - and is dependent upon context - per the first sentence, of the wikipedia article, you linked, stating:

> In electrical engineering, low voltage is a relative term, the definition varying by context.

The various standards, mentioned in that article, are in relation to “installations”, and power distribution. The standard in the UK (BS 7671), defines “high voltage”, as >600VAC difference between conductor(s), and earth.

A voltage greater than mains voltage, in any item of domestic electrical equipment, is absolutely “high voltage”. Hence why valve amp power supply terminals, are considered high tension (HT, i.e., high voltage), despite not exceeding the threshold, claimed in wikipedia.