When I last visited Cardiff Central station just over a month ago, the wiring had yet to be hung, see....
https://www.ontheupfast.com/v/photos/21936chg/27787343204/x43161-10-24-cardiff-central-cardiff So, it is obvious that much work has taken place, indeed at the time of writing this on 10.11.19, a posting has just been placed on the internet stating that the first electric test train has run into South Wales from Patchway to East Usk Junction as 3Z33 over the previous night. In this view, 800315 has just left Central station as the 5L54 ecs return working that will soon work back to Paddington.