3.2.2 Limitations One limitation of hot wire GTA welding is that it is not normally used for manual welding. There are also additional equipment costs for the hot wire power supply in addition to the cold wire GTAW equipment. The power supplies are not especially compact and portable for moving around in the field. In going from cold wire to hot wire GTAW, it may be necessary to change the groove design to one more suitable to hot wire and the increased deposition rate. There are some consumable costs such as the hot wire feed guide tube contact tips and tungsten electrodes. The cost of helium or helium argon mixes used as shield gas for some applications are greater than for straight argon and more gas is consumed. And there may be increased costs for training welding personnel.