We study the effect of all matter multiplets contained in 27 representation of E₆ GUT on gauge coupling unification in extra dimensions. Extra members of  27 multiplets of all three generations have their `zero modes' near m_t such that they can be directly probed. From TeV scale onwards extra dimensions open up, theory becomes N=2 supersymmetric and gauge couplings unify or they do not, depending on how we distribute matter fields and gauge fields in bulk and brane. We find three such possible embeddings which will lead to perfect gauge coupling unification below 100 TeV region for one extra dimension and lower than that if number of extra dimensions is larger.

PACS numbers: 04.50.+h, 11.25.Mj, 12.10.Dm