Englishman Lee Slattery had a 65, the day's best round, and was two shots back at 6-under 138 at Leopard Creek Country Club.
South African Ernie Els, who shot 69 to go with his opening 70, was in a group of six players tied for third three shots back. The group included first-round leader Sion Bebb of Wales, who had a 72 after opening with a 67.
Els was inconsistent again with four bogeys and seven birdies.
Sandys had five birdies and a bogey.
'I started getting really nervous on the back nine,' Sandys said. Even so, Sandys had three birdies in four holes from the 12th and dropped his only shot of the day at the 16th.
Northern Ireland's Darren Clarke shot a 69 and was six shots off the pace.