The given work considers the influence of the power supply type (diode rectifier DR-306 and upon new generation inverter Nebula-315) upon the chemical composition, microstructure, mechanical properties of the weld joints and health characteristics of the manual arc welding process. It has been found out that the power supply type has a significant influence upon the weld joints properties and health characteristics of the manual arc welding process. Using the inverter power supply type provides less heat input into a molten electrode metal drop which decreases silicium and manganese burning, improves impact resistance under low (negative) temperature and reduces the risk of workers respiratory diseases. The reliability of weld joints in metal constructions and technical devices in electrical, oil-producing, mining, chemical, engineering and other industries has a significant impact upon safety and economic efficiency. Manual arc welding with coated rods is one of the main technological processes for welding constructions inappropriate for rational mechanization, automation and robotization. The manual arc welding process is easier to use, more flexible and universal, requiring less auxiliary operations and equipment. That's why manual arc welding has no alternative when repairing, assembling and reconstructing technical devices. Works [1, 2] considered the influence of the power supply type upon the stability of the manual arc welding process, scattering and length of the heat affected area. We have carried out a number of experiments to estimate the influence of the power supply type upon the chemical composition, microstructure, mechanical properties of the weld joints and health characteristics of manual arc welding. To carry out the investigation we welded 09Mn2Si steel 59×6 tubes with LB-52U electrodes 3.2 mm in diameter and 45 steel with UONI 13/55 electrodes applying diode rectifier DR-306 and a new generation inverter Nebula-315 as power supplies. Analysis of the experimental data on the chemical composition of the weld joint  showed that the type of the power supply influences the weld joint chemical composition. Nebula 315 limits the short-circuit current (fig. 1) [1, 2]. The calculation shows that when using the inverter power supply, energy spent on electrode metal melting makes Q = 1,0870×10 7J per second as compared to Q = 1,2061×10 7J with diode rectifier. Thus, the diode rectifier reduces alloy burning (Si and Mn).