For drawing electrical wiring diagram of buildings, mostly two dimensional CAD programs are used. Drawing is done starting from the source (utility pole) to main power panel and then it is distributed towards to subpanels. Then, end points such as sockets, lighting armature, etc are defined. In this study several algorithms are developed in order to evaluate different part of drawing project. Tree structure of drawing is analyzed and all materials to be used are decided based on an algorithm. Apart from these, some of the supplies to be used in project but not shown in the drawings are also be chosen with certain criteria. These decision systems will result in efficiency of overall cost of the project. In wire drawing one of the most important point is the line drawing with reference to an object. Apart from light outlet all wires are referenced to walls. Furthermore, all supplies shown in drawings are allocated with reference to walls and with an angle to walls. In wiring diagram drawings, standard CAD programs have no ability for wire drawing with reference to walls. Besides that, suggestion and selection of the most appropriate supplies is not possible. These increase drawing time and result in very high cost calculation errors.