Open Infra Map; shows major electrical lines, power plants, gas & oil lines, and telecom/data centers. Gets its data from Open Street Map: https://openinframap.org/
For railways, there is a genre of "track diagrams" which are more like circuit diagrams for the railway, showing lines, crossovers, platforms, etc. The best ones for the UK are perhaps the Quail maps, which include all sorts of gory details, but are commercial:
Open Infra Map is just the kind of thing I was hoping for! I'm interested/surprised at how many megawatt batteries there are in the UK, and how many 10MW+ solar farms and at all the names of the offshore wind farms and where they connect back to.
https://www.trackmaps.co.uk/wp-content/uploads/2023/01/Book5...
There are some pretty good open ones though:
https://cartometro.com/cartes/metro-tram-london/index.php?st...