Scrum-half Rhodri Williams was the star of the show with a brace of tries. Back-row duo Luke Kendall and Sean Miles also crossed the whitewash, with James Garland adding five points with the boot.
Swansea grabbed tries through Jamie Thomas and Dan Baker, while Sam Davies kept the visitors in touch with 10 points to claim a losing bonus-point.
Llanelli could have stayed top with a win over Bedwas but crashed to a 30-16 defeat at Bridge Field.
Newport Gwent Dragons starlet Jack Dixon grabbed a try for the hosts along with Ross Wardle, Sam Feehan and Simon Grainger also dotted down.
Jordan Williams, who grabbed two tries to help the Scarlets to victory over Connacht last weekend, could not inspire a victory for the club side, but he did knock over 11 points to make the score line respectable.
The match of the day was at Sardis Road where Pontypridd snatched a 45-35 over Bridgend.
Ponty were cruising at the interval following tries from Dafydd Lockyer, Owen Williams and Lewis Williams before Bridgend fought back.
The Ravens dominated the second-half and they took the reigning champions to the wire. They scored tries through Matthew Dwyer, Glen Lewis and Jamie Murphy, while Ross Jones demonstrated his deadly accuracy with 20points from the boot.
But Ponty hit back with Owen Williams completing his hat-trick and Gareth James getting in on the act at the death – the burst of points denied the Ravens of a crucial bonus-point.
Elsewhere Newport continued their revival with a thrilling 28-25 win at Carmarthen Quins.
Ryan Prosser and Craig Everett both grabbed tries but it was Elliot Frewen that proved the difference, dotting down twice in an impressive performance.
Cross Keys piled the misery on Neath with a five-try 41-10 victory at Pandy Park. Former Welsh All Blacks centre Luke Ford, the son of Cardiff legend Steve, raced clear for try and he was joined on the scoreboard by Elliott Jones, Dan Hodge and Luke Williams.
Keys were also rewarded for their forward dominance with a penalty try while Neath claimed consolation scores through Ryan Evans and Alun Wyn Davies.
Cardiff will host Aberavon at the Arms Park tomorrow as the Wizards bid to end their winless start to the season.
