Peel the corn husks from the cob. Rinse the corn on the cob and remove any excess husks strings. Heat a grill to medium-high heat. In a bowl, melt the butter in the microwave. Add the lime zest, juice, garlic powder, salt and pepper and stir. Brush the corn on the cob with butter on the top side. Add the corn to the grill and grill on all sides for a few minutes on each side. When the corn is nice and golden brown (on parts) and tender, remove from the grill and place on a plate. Brush the cooked corn with more of the butter. Serve warm.