In C8, the 'tube' functions alone the bulb Z access - just rotate into position and set the desired length. To create the illusion of an actual tube light illumination, Anything Glows can be applied to a Vertex cylinder object. 

The Anything Glows will create a miniature bulb light at each vertex point of the object - more vertexes, more fidelity in the illumination. 

Now that Indirect Lighting is available as a render option, it is preferable to use that and assign a glow shader function to an object to create illumination; in my opinion, it creates better final results than Anything Glows since individual points of light do not show up in reflected highlights on other objects in the scene.