Earthing & Bonding in Merton

About earthing & bonding in Merton

Earthing and bonding are fundamental safety measures in every electrical installation. The earthing system provides a path for fault current to flow safely to earth, causing protective devices (fuses, MCBs, RCDs) to disconnect the supply. Bonding connects all metallic services (gas, water, oil pipes) to the earthing system, preventing dangerous voltage differences between them. An earthing and bonding upgrade brings these systems up to the current BS 7671 standard — replacing undersized conductors, adding missing bonds, and ensuring the earth fault loop impedance is low enough for protective devices to operate within the required time.

Inadequate earthing and bonding is one of the most common defects found on EICRs. Without proper earthing, a fault on an appliance or circuit may not trip the protective device, leaving the metalwork live and creating a serious shock hazard. Without bonding, metallic pipes can carry dangerous voltages — particularly in bathrooms where the risk of electric shock is highest. If your EICR has flagged earthing or bonding deficiencies (C1 or C2 codes), this work is essential for safety. It is also required as part of consumer unit upgrades, rewires, and new circuit installations.

What's included

• Assessment of existing earthing arrangement (TN-S, TN-C-S, or TT)
• Installation or upgrade of main earthing conductor (typically 16mm²)
• Main protective bonding to gas, water, and oil services (10mm²)
• Supplementary bonding in bathrooms and kitchens where required (4mm²)
• BS 951 bonding clamps and warning labels at all connections
• Earth rod installation for TT systems (where applicable)
• Earth fault loop impedance testing on all circuits
• Bonding continuity verification
• Electrical Installation Certificate or Minor Works Certificate

Typical cost

Earthing & Bonding in Merton typically costs £150–£500 per property. Every job is different — describe what you need and a qualified electrician will quote you directly.

See full pricing breakdown →

Regulations & standards

• BS 7671:2018+A2:2022 — Chapter 54 (Earthing Arrangements and Protective Conductors): Specifies the requirements for earthing arrangements, main earthing terminals, earthing conductors, protective bonding conductors, and earth electrodes. Defines the minimum conductor sizes and connection methods.
• BS 7671:2018+A2:2022 — Regulation 411 (Automatic Disconnection of Supply): Requires that the earthing system provides a sufficiently low impedance path for fault current to flow, enabling protective devices to disconnect the supply within 0.4 seconds (for socket circuits) or 5 seconds (for fixed equipment circuits).
• Part P of the Building Regulations: Earthing and bonding work that involves the main earthing terminal or is carried out as part of a consumer unit upgrade or new circuit installation is notifiable. Standalone bonding upgrades may be covered by a Minor Works Certificate.
• Electricity Safety, Quality and Continuity Regulations 2002 (ESQCR): Governs the DNO's responsibility to provide an earthing facility (where available) and the requirements for connection at the supply intake. Relevant when the earthing arrangement involves the DNO's infrastructure.