Just come accross a short film on youtube made at Llechwedd in the 1960's showing the 'coalition' working from electric overhead cables.
[youtube]aoCHbq1JF5g[/youtube]
[tweak]Tweaked to embed the video clip[/tweak]
Bellach dim ond swn y gwynt yn chwibian, lle bu gynt yr engan ar cynion yn tincian.