The Midlands and North East are also affected after problems in London and the South East.
Blackouts have been reported in London and the South East, as well as the Midlands and the North West.
UK Power Networks, who control power lines for London and the South East, and Western Power Distribution in Midlands, the South West and Wales both confirmed widespread outages.
UK Power Networks tweeted on Friday evening: “We’re aware of a power cut affecting large parts of London and South East.
“We believe this is due to a failure on National Grid’s network, which is affecting our customers.”
⚠️ #TLUpdates – Due to failure of the electricity supply, train services running across the whole network may be cancelled or delayed.
ℹ️ More information to follow.
— Thameslink (@TLRailUK) August 9, 2019
Western Power Distribution shared a similar message, and said they are in the process of restoring power to customers.
Cheshire Police said they were aware of a power cut in the Ellesmere Port area.
The drop in power is also affecting travel.
⚠️Power supply problems are currently causing disruption to a large number of train services. Information screens in some areas are also affected. ⚠️
Please check https://t.co/ZDVeTk0wcS for the latest updates
— National Rail (@nationalrailenq) August 9, 2019
Train services across England and Wales are facing reported delays and cancellations.
A Network Rail spokeswoman said: “There was a power surge on the national grid this evening which means we lost power to all our signalling over a wide area, including the Newport, Gloucester, Ashford, Bristol, Eastbourne, Hastings, Three Bridges and Exeter areas.
“All trains were stopped while our back-up signalling system started up.”
Many Thameslink trains are also “at a stand” between London and Bedford.
#LNERUpdate – Due to reports of a major power failure, the following services have been cancelled;17:48 #KingsCross to #Leeds19:16 #Leeds to #KingsCrossTrain services may be cancelled or delayed or revised at short notice.
— London North Eastern Railway (@LNER) August 9, 2019
Traffic lights in the capital are also experiencing some problems and police could be forced to man busy junctions where traffic lights have been shut down, Transport for London said.
A TfL spokeswoman said some traffic lights are “not working” but the scale of the problem is not yet known.
Police officers could be called in to “manage the busy junctions, to physically manage them themselves”, she said.
“We’re just assessing how many traffic signals are out.”