when my wife works overtime it looks like they drop her pay to minimum wage which is 8.15 ph in ohio. is this legal

This is not legal. Your wife should receive 1.5 times her regular rate of pay when working overtime. We encourage you to contact our office to speak with our Ohio overtime lawyer further about your wife's right to recover. She may be entitled to unpaid overtime, liquidated damages, and attorney's fees. We offer free consultations and work on a contingency fee for clients throughout Ohio.   Ohio overtime attorney http://mcoffmanlegal.com/practice-areas/wages-and-overtime/ohio-overtime-attorney-flsa/