I live in an a frame with exposed beams built out of 3 2x12 ( not glu lams )
21 inch o.c. . I want to install additional lighting and using raceways cut into the bottom of the center 2x12 about 1/2" . I'd also would like to drill into the bottom to install smaller dia led lights. Obviously I'm worried about weakening the members, but also consider these beams to be overbuilt.