Acceptable voltage between earth, Line,Neutral - Single Phase
Normal case:

Live-neutral: around 240v

Live-earth: around 240v

Earth-neutral: around 0v

With neutral and live swapped:

Live-neutral: around 240v

Live-earth: around 0v

Earth-neutral: around 240v

So maybe you have a setup were neutral and live got swapped. That's not a safe setup. But to be sure, please check the difference in voltage for all 3 cases.