Sub-Mains and Three Phase Installations

We specialise in providing Sub-Mains and Three Phase Installations.

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Sub-main distribution systems form the backbone of your building’s electrical infrastructure. We install three-phase and single-phase sub-mains to feed distribution boards, plant rooms, and final circuits across a wide range of commercial and industrial environments.

Our sub-main installations typically involve steel wire armoured (SWA) cable in single-core or multi-core formats. These are implemented in containment systems such as tray, basket, or conduit, depending on route complexity and cable size. Our cable sizes are based on calculated loads, installation conditions and future growth — ensuring compliance with BS 7671 and discrimination coordination with existing protection devices.

Terminations are made using industry-standard methods with gland plates, cleats, fixings and earthing applied according to site layout and the physical characteristics of the cable. Where required, we install new distribution boards, switch disconnectors, or MCCB panels to complete the system.

These installations are often completed as part of wider fit-out or infrastructure upgrade projects, and we’re experienced in coordinating our works alongside other services, containment runs and programme constraints.