The conductance and the current-voltage characteristics of metallic single wall carbon nanotube bundles have been measured between 4.2 and 330 K using 10-30 ns electric pulses to avoid overheating. The current-voltage characteristics at different temperatures collapse to a single curve when plotted in the specific coordinates following from the Tomonaga-Luttinger (T- L) liquid concept. Direct evidence is obtained for the existence of a T-L liquid phase up to 190 K and the system shows a transition between the T-L liquid state and a Mott insulating phase below 25 K. (C) 2010 American Institute of Physics. [doi:10.1063/1.3467464]