This research paper presents the electrofusion welding of the polyethylene electric-welding pipe fitting on the five prepared samples. The polyethylene electric-welding pipe fitting which is placed in the middle of each prepared sample has been welded using electrofusion, but all of them are welded under different welding conditions. Therefore, the first sample is welded in a way that it is consistent with common practice, i.e. according to the instructions of the manufacturer's equipment for electrofusion welding, and according to the instructions of the manufacturer of pipes and electrical fittings. The second and the third sample show a simulated power outage with different durations of welding. The fourth sample is cooled down to -12°C, and the fifth one is heated to 100°C, and in this way the incorrect intake of the outdoor air temperature into the welding device is simulated. After the electrofusion welding of each sample under different conditions, the pressure test of each sample was performed using water as a medium with the purpose of testing the tightness of the welding joint. Since the pressure testing has proven that some samples show leakage of the welding joint, the analysis of each welding joint was performed in order to see and determine what happened to each of them.