GWR 800 running diesel under wires

[Joseph T]

I'm currently on the morning service from Paddington to Carmarthen travelling between Reading and Cardiff and as I departed Didcot Parkway, I sensed the diesel engines running despite the train being under the wires for my whole journey. Any idea why?

 

[Cowley]

Under discussion here:

800/802s running on engines even under wires

Sorry if it's a stupid question but it's been bugging me a bit. I travel from South Wales to London occasionally, and the last few times they have not been switching onto electric at Cardiff. It's not consistent, I'm sat at Paddington ATM on an 2x800 and pantographs are down on all of them with...

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