A supporting bracket assembly for a horizontal lifeline cable comprises a base plate, bracket means and holding means for the cable. External audio communications devices communicate with an internal headset by way of electrical conductors inherent in a mounting post. A wireless communication arrangement may also provide for authentication of devices that are allowed by the source to be powered or otherwise charged. The collector device is disposed symmetrically about the mean collection axis in the half-space containing the laser beams focused on the target and inside a conical space centered on the mean collection axis with a vertex situated at the target and a half-angle at the vertex that is less than the angle of inclination of the focused laser beams relative to the mean collection axis.