Domakihub Bond Metal Pipework for Electrical Safety: A Homeowner's Guide
What pipe bonding is, why it matters in every Greek home and rental, and when a licensed electrician must do it.
Reviewed by Domakihub home & decor pros · 2026-06-23 · 5 min read
Metal water pipes, gas pipes, and heating risers running through your home can become live conductors if the electrical installation develops a fault — posing a lethal shock risk to anyone who touches them. Equipotential bonding is the practice of connecting all exposed metalwork to the earth system so that no dangerous voltage difference can exist between surfaces. The video above shows how bonding clamps are physically fitted to metallic pipes; this article walks through the underlying principles, the required steps, and when Greek regulations demand a certified electrician rather than a DIY approach.
What Is Equipotential Bonding and Why Does It Matter?
Equipotential bonding creates an electrically continuous loop between all metal services entering or running through a building and the main earth terminal of the consumer unit. The goal is not to carry current in normal operation but to ensure that, in a fault condition, every metallic surface a person could simultaneously touch sits at the same electrical potential — so no current flows through the body.
In Greece, internal electrical installations must comply with ELOT HD 384 (the Greek adoption of IEC 60364). This standard distinguishes between main protective bonding — connecting incoming water, gas, oil, and central-heating pipes at the point they enter the building — and supplementary bonding, which is required inside specific locations such as bathrooms and wet rooms where the shock risk is higher.
Main Bonding vs. Supplementary Bonding: The Key Distinction
Main protective bonding conductors run from the main earthing terminal to each incoming metal service. They are typically green-and-yellow insulated copper conductors sized at a minimum of 6 mm² (often 10 mm²), connected with BS 951-type clamps bearing the safety label. These connections must be made on the owner-side of any meter or stop-valve so the bond remains effective even when a service is shut off.
Supplementary bonding applies within zones such as bathrooms, where additional conductors link all simultaneously accessible metal parts — pipes, radiators, metal baths, and exposed metal fittings — to one another and to the local earth point. Both types of bonding are inspectable, tested for continuity, and must be documented on the Electrical Installation Certificate (YDE in Greece). Installing, modifying, or certifying either type is work reserved for a licensed electrician.
How Pipe Bonding Is Carried Out (Step by Step)
- 1
Identify all incoming metal services
Before any work begins, trace every metallic pipe entering the building — water supply, gas supply, oil supply, and central-heating flow and return. Make a note of where each pipe first becomes accessible inside the building after penetrating the wall or floor, because the bonding connection must be made as close to the entry point as possible and upstream of any internal isolation valve.
- 2
Size and prepare the bonding conductors
Select green-and-yellow insulated copper cable of the correct cross-section: under ELOT HD 384, main bonding conductors are typically 6 mm² for a 16 mm² main earth conductor, scaling up to 10 mm² or more for larger installations. Cut the conductor to the shortest practical run to the main earthing terminal, strip back approximately 15 mm of insulation at each end, and check the conductor is free of nicks or damage that could create a high-resistance joint.
- 3
Fit the BS 951 bonding clamps
BS 951 clamps are the industry-standard method for attaching a bonding conductor to a metal pipe. Select the clamp size that matches the pipe diameter — undersized clamps can damage pipe walls and oversized clamps will not grip reliably. Clean the pipe surface to bare metal at the intended clamp location (remove paint, scale, or corrosion with fine abrasive paper), position the clamp body so the label 'Safety Electrical Connection — Do Not Remove' faces outward, insert the conductor end, and tighten the clamping screw to the torque specified by the manufacturer. Never use push-fit or plastic pipe adaptors as substitute contact points.
- 4
Connect to the main earthing terminal
Route the conductor from the clamp to the main earthing terminal (MET) inside the consumer unit or distribution board, following the shortest, most direct path and securing it with appropriate cable clips every 400 mm on horizontal runs and every 500 mm on vertical runs. At the MET, insert the conductor into the dedicated bonding terminal and tighten to the manufacturer's torque value. Each service must have its own terminal position — do not daisy-chain services through a single conductor.
- 5
Test continuity and document the installation
Once connected, a licensed electrician uses a low-resistance ohmmeter to measure the resistance of each bonding conductor from the clamp to the MET. A reading above 0.05 Ω on a new installation warrants investigation — common causes include a loose clamp, corroded pipe surface, or undersized conductor. Results must be recorded on the installation's test schedule and incorporated into the YDE certificate. In Greece, any new bonding installation or modification to an existing one requires a YDE declaration signed by a licensed (αδειούχος) electrician, which is also needed for building insurance and DEDDIE/HEDNO compliance.
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FAQ
- Can a homeowner fit bonding clamps themselves in Greece?
- The physical act of clamping a conductor to a pipe is mechanically simple, but the work cannot be legally certified or signed off unless a licensed Greek electrician carries out or directly supervises the installation. Without a valid YDE declaration covering the bonding, your building insurance may be void and DEDDIE can reject the connection. Engage a licensed electrician and treat the physical work as something you can prepare for — pipe surfaces clean, conductor lengths measured — but not complete unsupervised.
- Do plastic (PVC or PEX) water pipes need bonding?
- No. Only conductive metalwork that can introduce a dangerous potential into the building requires bonding. If your incoming water supply is entirely plastic and there is no exposed metalwork reachable in bathroom zones, main bonding of the water service is not required. However, if any metal fitting — a copper manifold, a metal-bodied stop-valve, or a steel heating riser — is present and reachable, that metalwork must still be bonded. A licensed electrician can assess each situation correctly.
- How often should bonding connections be inspected in a rental property or hotel?
- ELOT HD 384 and Greek rental regulations recommend a periodic inspection of electrical installations every five years for residential lettings and more frequently for higher-risk premises such as hotels and holiday rental properties. The inspection includes a visual check of all bonding clamps (looking for corrosion, missing labels, loose conductors) and a continuity test of every bonding conductor. Keeping an up-to-date inspection record protects both owners and guests and is increasingly required by holiday-rental platforms operating in Greece.