Abstract: A protective device is provided to prevent humans from accidentally falling through openings in roofs or floors, including the domes of curb-mounted skylights and temporary utility chases that are surrounded by a raised curb. The protective device is secured to the raised curb by clamps that do not penetrate the curb, skylight frame, floor or roof, and therefore do not compromise the water-tight integrity thereof. In the case of an opening type skylight, by securing the protective device to the curb, no interference is contributed to the skylight to hinder the opening mechanism of the skylight.