From an electronics forum:
"To talk of "European" equipment here is not useful, since Europe has many different electrical standards, varying from country to country.
However, if the equipment concerned operates on a compatible voltage, and if the equipment concerned is not sensitive to the different AC frequency, then you could connect a European device to an American supply.
To take one example, the main difference between an American domestic 240 V supply and a UK 240 V domestic supply is the grounding/earthing arrangement. In the US outlet both legs of the 240 V supply are hot and are 120 V from ground. In the UK 240 V supply one leg is live and one leg is neutral (close to earth potential). In other European countries the supply voltage and grounding arrangements may be different.
As mentioned by other posters, European devices are designed to operate safely in a variety of different supply situations with both supply legs fully isolated and insulated from exposed parts. So a European nominal 230 V device can be plugged into a US 240 V socket without problems."
Can anyone confirm or refute this? Pic attached.
Thanks.
PS - I also saw that tying the outputs of a 2 pole breaker gives 240v (using neutral). But does that not make every 120v breaker output 240v also by tying the 120v buses together through that breaker?