Novant Health Inc. said Tuesday it has raised its minimum wage for the second time in 18 months, this time by $1.50 to $12.50. The Winston-Salem not-for-profit health-care system said about 5,000 employees in North Carolina, including about 2,300 in the Triad, benefit from the increase. Overall, the new minimum wage affects about 18 percent of Novant’s four-state workforce of 28,092, as well as 28 percent of its Forsyth County workforce of 8,145.