The Tykes made a move for Caig after deciding not to renew the contract of current number one Sasa Ilic – one of the heroes of Charlton Athletic’s penalty shootout victory over the Mackems in the 1998 Division One play-off final.
Caig is still to make his first-team debut for United, having joined the club on a free transfer from Hibs almost 12 months ago.
The 29-year-old should find himself at home in the second division though, having played more than 250 Football League games during spells with Carlisle United and Blackpool earlier in his career.