The uncertainty treatment of power injections is one of the most important problems in load flow studies. One method is called the Fuzzy Load Flow (FLF), where uncertainty of input variables is modeled with fuzzy numbers. In FLF fuzzy numbers are traditionally decomposed in alpha-cuts and interval arithmetic is used. This paper introduces the use of LR fuzzy numbers’ arithmetic and the transformation method for the solution of FLF. This last method counteracts the short-comings of the interval arithmetic. Adequate fuzzy numbers implementations and appropriate fuzzy arithmetic contribute to precision and improve the general outcome. A comparison between three types of fuzzy arithmetic is made. Finally, the approaches presented are applied in a test system.