Abstract: A UV lamp rack assembly usable in an ultraviolet ray wastewater treatment system, the rack including a horizontal hanger bar. When the assembly is installed in a channel through which a stream of wastewater to be treated is conducted, the bar is then supported above the channel in the flow direction of the stream. Depending from the bar at an upstream position is a vertical rod along which sleeves are pivotally mounted at spaced points thereon whereby each sleeve can be swiveled in a horizontal plane. Depending from the bar at a downstream position is a vertical conduit along which detachable lamp couplers are mounted at corresponding points, each coupler housing a lamp socket that is connected through the conduit to a power source. Extending between each sleeve and the coupler corresponding thereto is a lamp unit formed by a transparent protective tube enclosed at its upstream end and housing an elongated UV lamp whose terminal pins are at the downstream end.