Domakihub How to Spur a New Socket from a Ring Main
Understand the process, rules, and when to call a licensed electrician.
Reviewed by Domakihub home & decor pros · 2026-06-23 · 5 min read
Adding an extra socket by spurring off an existing ring main is one of the most common small electrical jobs requested in Greek homes, holiday villas, and hotel rooms — especially when a renovation reveals too few outlets for modern use. The video above shows a qualified electrician carrying out the work on site, from opening the donor socket to making the final connections. This guide explains the concepts, preparation steps, and rules so you can have a productive conversation with your electrician and know exactly what work is being done.
What Is a Ring Main and What Is a Spur?
A ring main (or ring final circuit) is a loop of 2.5 mm² cable that starts at the consumer unit, visits a series of socket outlets around a room or floor, and returns to the same breaker. Because the circuit is a closed loop, current can flow from both directions to any socket, which reduces voltage drop and allows the circuit to serve more sockets safely.
A spur is a branch cable that taps off the ring at a single point — either at an existing socket or through a junction box — and feeds one additional socket outlet. The spur cable is a dead end: it does not return to the consumer unit, and current can only approach the new socket from one direction. This is why the rules strictly limit what can hang off a spur.
The Key Rules Before Any Work Starts
In the UK and in countries following IEC wiring conventions (which Greece uses under ELOT HD 384), a spur from a ring final circuit may supply only one single or double socket outlet, or one fused connection unit. You cannot daisy-chain a second socket onto a spur, and you cannot take a spur from a point that is already itself a spur. Violating these rules is a common DIY mistake that can cause the circuit to overheat under load.
In Greece, all fixed electrical installation work in domestic and commercial premises must be carried out by a licensed electrician (ηλεκτρολόγος εγκαταστάτης) holding a valid ΓΓΒΕΕ licence. The completed work must be covered by a Υπεύθυνη Δήλωση Εγκαταστάτη (Installer's Declaration of Responsibility), which is a legal requirement for building compliance and insurance. Do not attempt to open a live consumer unit or modify ring wiring yourself.
Preparing for the Job: What You Can Do
Good preparation cuts the electrician's time on site and therefore your bill. Walk the room and decide exactly where the new socket will go — ideally on the same wall as an existing socket to minimise cable runs. Measure the distance from the nearest existing outlet and note whether the wall is solid masonry (common in Greek construction) or plasterboard, as this affects how the cable will be chased or surface-mounted.
Check that you have enough sockets on the overall floor: a standard ring main for a living area should not have more than two spurs in total. If the room already has two spurs, the electrician will need to extend the ring or add a new circuit — a bigger job. Being aware of this before the call saves a surprise on the day.
How a Licensed Electrician Spurs a New Socket: Step by Step
- 1
Isolate and verify the circuit is dead
The electrician switches off the relevant breaker at the consumer unit and uses a voltage indicator or test meter to confirm there is no live voltage at the donor socket before any screws are removed. In Greece, the consumer unit cover must be replaced and locked out while the socket is open. Never rely on a switch alone — always test.
- 2
Open the donor socket and identify ring conductors
The backplate of the existing socket is unscrewed and eased forward. A ring socket will typically have two sets of conductors entering the back — live (brown), neutral (blue), and earth (green/yellow) — one from each direction of the ring. The electrician confirms this with a continuity tester. If only one set of conductors is present, the socket is already a spur and cannot host another spur; a different donor point must be found.
- 3
Run the new spur cable
A length of 2.5 mm² twin-and-earth cable is routed from the donor socket to the new socket position. In solid masonry walls — the norm in Greek construction — this means chasing a channel (regroba) into the plaster, laying the cable in conduit or sleeving, and making good. In dry-lined walls, the cable can be fished through the cavity. Surface trunking is a faster, reversible option often preferred in holiday rentals where owners want minimal wall damage.
- 4
Make the connections at both ends
At the donor socket, the spur conductors are connected to the existing terminals alongside the ring conductors (live to live, neutral to neutral, earth to earth). Only one set of spur conductors is added here, not a second ring cable. At the new socket, the spur conductors are connected to the single set of terminals. All cores are trimmed to equal length, insulation is stripped cleanly, and ferrules or sleeved terminations are used where required by the socket design.
- 5
Test, certify, and document
Before the socket cover is fitted, the electrician tests insulation resistance between conductors and between conductors and earth, and checks polarity. Once confirmed correct, the circuit is re-energised and each socket is tested for correct live, neutral, and earth connections with a socket tester. In Greece the electrician issues an updated Υπεύθυνη Δήλωση covering the new outlet. Keep this document with the property file — it is required for insurance claims and future sale of the property.
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FAQ
- Can I add more than one new socket on a single spur?
- No. A spur from a ring final circuit is limited to one single or double socket outlet (or one fused connection unit). If you need two new sockets in a location, the electrician must either run two separate spurs from two different points on the ring, or extend the ring itself to include the new outlets as full ring sockets.
- How do I know if my existing socket is on a ring main or is already a spur?
- A ring socket will have two cables entering the back — one from each direction of the loop. A spur socket will have only one cable. Your electrician confirms this with a continuity test: they disconnect one cable and test from its conductors back through the ring to the other cable. Do not attempt to open the socket yourself; have a licensed electrician check it as part of quoting the job.
- Is a permit or official notification required for this work in Greece?
- For minor additions such as a single spur socket within an existing circuit in a residential property, Greek law requires the licensed electrician to issue an updated Υπεύθυνη Δήλωση Εγκαταστάτη rather than a full building permit. However, if the work is part of a larger renovation that includes structural changes or a new consumer unit, a formal permit (οικοδομική άδεια or έγκριση εργασιών μικρής κλίμακας) may be required. Your electrician is responsible for advising you on this.