An electrofusion equal diameter tee is a type of plastic pipe fitting (usually made from polyethylene, PE) used to create a branch connection in a pipeline. It has three openings of the same size (diameter) arranged in a "T" shape. The fitting contains embedded electrical heating wires. When connected to a special power supply, these wires heat up, melting the plastic both inside the fitting and on the outside of the pipes inserted into it. As the plastic cools, it forms a strong, permanent, and leak-proof seal between the tee and all three pipe ends.