Richard Hopkins crossed just before half-time and Adam Jones then touched down in the second half to open a 15-3 lead. But Caernarfon launched a dramatic comeback with three quick-fire tries from wing Iolo Hughes, Gwilym Jones and Dylan Gwyn to lead 22-15.
Mold’s Daniel Payne crossed four minutes from time but Jack Martin missed the conversion that could have claimed a draw. Pwllheli romped to second place with a comfortable 34-13 win over Abergele.
Bottom side COBRA made life difficult for Ruthin who finally edged out 7-3 winners after Michael James Evans scored the only try of a tight-contest.
Andre Soroko put Division One East leaders Penallta on track for a 29-16 victoryover struggling Brecon to extend their grip on top spot. Brynmawr made light work of bottom side Blackwood with a 34-0 demolition.
Ynysybwl overtook Blaenavon for third place last week and claimed a 24-13 win over the same opponents. Corey James bagged himself two tries while Jonathan Gough and Nathan Ellis also crossed and Dion McIntosh kicked two conversions.
Skewen continued their unbeaten start to the season in Division One West-Central after overcoming their toughest test of the season.
Second-placed Ammanford made life difficult for the league leaders who had Edward Price to thank for the only try of the match and claim a ninth win in a row.
Mark Simmons inspired Bonymaen to a 15-12 home win against Maesteg. He scored 10 of his sides points as they moved up to third in the table. A try from Lewis McClean was not enough for the visitors to wrestle victory on this occasion.