With the vanishing of the fossil primary resources and the carbon impact issues, the efficient use of energy has become a major priority. Lighting is an important element of expenditure as it is easy to act on it. The Light Emitting Diode (LED) technology opens many perspectives in this field due to its higher energy efficiency. LED could indeed become in a near future a replacement for fluorescent tubes. LED's tubes have specific thermal and electrical needs; this work is focused therefore on optimization studies in terms of association topologies: serial versus parallel. The starting point is electrical equivalent models extracted from single LED. The choice of combinations is guided by the required performance in terms of light quality by paying attention to the overall consumption of the lighting system. The final target is the evaluation of losses reduction when the individual AC/DC conversion circuits integrated in the lamp bases are replaced by a DC/DC global distribution scheme. This approach was adopted to power the lighting of single room from a low DC voltage weakly regulated power grid.