Penallta Colliery was built in 1906-09 and was one of the last steam-powered collieries constructed, although it did also generate its own electricity. Its layout was the model for collieries built after it with one common engine-hall to replace the previous separate engine-houses that adjoined each shaft. The large engine-hall retained its art-nouveau-style tiling although it was largely re-equipped in the 1960s.
B.A.Malaws, RCAHMW, 11 February 2009.