Powell, 31, has been linked with a code switch previously, when Brian Noble made an attempt to sign him while in charge at Crusaders in 2010.
His departure from Sale was confirmed by the club’s chief executive and coach Steve Diamond, and he will leave the Salford City Stadium at the end of the rugby union season to join up with the Warriors.
Powell has played 23 tests for Wales, and has also turned out at club level for Cardiff Blues, Leicester Tigers and London Wasps.
A recognised number eight in union, he is likely to line-up in the front row in the 13 man code.
Harris is the current assistant coach at Wigan.