Are All London Underground Lines Electrified? Yes—Since 1940

Every line on the London Underground network is electrified. There are no diesel, steam, or battery-only passenger services on the Tube.

The Timeline

• 1890: World's first electric underground railway opens—City & South London Railway (now Northern Line Bank branch), Stockwell to King William Street.
• 1900s–1930s: Deep-level tube lines (Central, Piccadilly, Bakerloo, etc.) built electric from day one.
• 1933: London Passenger Transport Board formed; electrification of remaining sub-surface lines (District, Metropolitan, Circle, Hammersmith & City) accelerated.
• 1940: Last steam-hauled passenger service on the Underground ends (Metropolitan Line beyond Rickmansworth). Full electrification achieved.

Current Systems

• Four-rail DC (630 V): Unique to LU. Top-contact third rail (+420 V) + fourth rail (-210 V) for return current (reduces stray corrosion). Used on all deep-tube and sub-surface lines.
• Overhead AC (25 kV): Only on the few Network Rail sections shared with mainline trains (e.g., parts of Metropolitan Line north of Harrow, District Line to Upminster).

So yes—every Tube train you board draws power from the rails (or wires). The only non-electric vehicles on the network are engineering/maintenance locomotives.