For Glamorgan

19 balls – SJ Walters v Lancashire at Colwyn Bay, 2011 (CB40)
21 balls – MP Maynard v Lincolnshire at Swansea, 1994 (NWT)
21 balls – JWM Dalrymple v Surrey at The Oval, 2010 (P40)
22 balls – Majid Khan v Northamptonshire at Wellingborough, 1975 (SL)
22 balls – DA Douthwaite v Kent at Canterbury, 2022 (RLC)

Against Glamorgan

16 balls – GD Rose for Somerset at Neath, 1990 (SL)
18 balls – JC Buttler for Somerset at Taunton, 2010 (P40)