Paul,
I think the Tyne and Wear Metro and Dublin use 1500V DC and Manchester Metro 750V DC overhead – I’m not too sure about Sheffield. Traditional tramway (trolley) systems such as Blackpool, Manx Electric and Snaefell Mountain Railways plus Llandudno, Crich, and Seaton use 550V DC.
Interesting that London Underground (4 rail) and old British Rail (3 rail) use different voltages of 660V and 750V respectively, especially as they share the same tracks in numerous place, i.e at Richmond and Wimbledon on the District and on the Bakerloo and Metropolitan sections. Any idea how they do that – can the Underground stock take the extra voltage or is the fourth rail energized to 90V above ground where the two systems mix?
