The home side led at half-time thanks to a Josh Prosser penalty, but Josh Lewis replied for Vale after the break to lock the game up at 3-3.
It stayed that way until the dying moments when Wes Cunliffe intercepted a stray pass and cantered over for the match winning try. Lewis converted to seal the victory and send Ebbw Vale one point clear at the top.
Mid-table Beddau ambushed third placed Newbridge, winning 9-7. Newbridge scored the only try of the game, when they were awarded a penalty try by the referee, and Neil Burnett converted.
But nine points from the boot of Beddau’s Tom Benjamin clinched the victory for the home side, allowing them to close the gap on Llanharan to two points in seventh place..
Pontypool’s woes continued as they went down 11-3 at Bonymaen. The visitors conceded a try, but could only respond with a solitary Clayton Gullis penalty, enabling Bonymaen to move away from the bottom two into 10th place.
The weather wrecked havoc with the rest of the fixtures and the games at Cardiff Met, Llanharan, Whitland and Bridgend Athletic were all postponed.