A ring main is one of the most important parts of an electrical circuit. Officially called a ring circuit, it carries electricity from the consumer unit to the sockets.
Wiring a ring main is one of the most important tasks when building a new home. Whether you want to install it yourself or keep tabs on the electrician, this guide will teach you how to do it.
How To Wire A Ring Main
Ring mains are domestic electrical circuits that carry the electricity from the consumer unit to the sockets before returning to the consumer unit.
The circuit circles the entire floor or a room. Hence, the name.
While the consumer unit is generally installed by a contractor or your electricity provider, you may want to install the ring circuit yourself. Here’s how to do it.
What You’ll Need
- 2.5mm cables carrying twin and earth wires
- 30A fuse or 32A MCB fuse
- Spur sockets
- Junction boxes
- Insulating tape
- Corrugated sleeve
- Electric hammer breaker
- Wire stripper
- Tape measure
1. Obtain Planning Permission
Whether you want to replace the cables in an existing ring main or install a new circuit, the first thing to do is to give notice to your Local Council and obtain the necessary permits.
The work shouldn’t necessarily be carried out by an electrician, but you must ensure that you’re competent enough to wire your electric installation. This means that you must comply with the electrical installation requirements set out by the British Standards Institution BS 7671:2018.
Unless the work is carried out by a qualified electrician who is registered on a government-approved scheme, you must also report all work to your Local Authority Building Control.
2. Draw Your Wiring Diagram
The easiest way to install a ring main is by drawing a wiring diagram.
Decide whether you want the ring circuit to serve the entire floor, the whole house, or only a room. While there is no general rule, most homes have two or three ring mains:
- One serving the ground floor, except for the kitchen
- One serving the upper floor
- A separate ring circuit for the kitchen
Most electricians install separate circuits for each floor and the kitchen to prevent overloading. However, the number of circuits you need is generally determined by the size of your home.
According to UK regulations, a ring main cannot serve a floor area larger than 100 m². The maximum load for a circuit is 7,500 watts; hence, the preference for a separate kitchen circuit.
Of course, you can install a ring main in each room if you prefer, or build separate circuits for the bathroom, kitchen, and living and sleeping areas.
The only thing to keep in mind is that each circuit needs a separate terminal on the consumer unit. The terminal can be a 30-amp fuse or a 32-amp miniature circuit breaker (MCB).
This video explains how to draw a ring main wiring diagram:
3. Cut The Trenches
Once you have the diagram, measure and mark the position of each socket on the walls.
Draw a line from the consumer unit to the first socket, then continue to the next socket and so on, to connect all sockets. Draw a final line from the last socket back to the consumer unit.
Use these lines to cut trenches for the cable into your wall. Also, cut out openings for the sockets and the junction box. A junction box is needed if you want to install spurs.
4. Connect The Cable To The Terminal
Connecting the conductor cable to the consumer unit terminal is as easy as fastening the wires in place.
Use your wire stripper to remove the insulation from the end of the cable. Pay attention to prevent damaging the conductors or breaking the strands while removing the insulation.
Insert the cable into the terminal point of entry, making sure that each of the three wires (live, neutral, and earth) are aligned correctly. Fasten the screw on the terminal to fix the cable in place.
5. Wire The Circuit
Run the cable from the consumer unit to the first socket or the junction box (if installed) – don’t forget to run the length of the cable through a corrugated sleeve beforehand.
Connect the cable to the first socket in the same way you connected it to the consumer unit. Run another cable from the first socket to the next. Repeat for all other sockets.
Run a final cable from the last socket to the consumer unit and connect it to the terminal that serves the circuit.
You can now close the trenches and repeat for all other ring mains you want to install.
Use the same method to install a ring circuit in your shed or garage, connecting the circuit to a fuse box.
Ring Main Vs. Radial Circuit
Ring mains and radial circuits are very similar. The only difference is that the radial circuit stops at the last socket or light fixture, whereas the ring main returns to the consumer unit.
Radial circuits have become more and more popular in the UK thanks to their increased service reliability and fewer voltage fluctuations than ring circuits.
Ring mains allow the use of wires with half the current-carrying capacity of radial circuits and are often the cheapest to install. However, the load is shared between the two cables connected to the consumer unit, and voltage fluctuations are more frequent.
Can I install a ring final circuit myself?
Yes, you can install a ring final circuit yourself. However, the Local Authority Building Control or your Local Council may require the work to be inspected by a qualified electrician.
If you decide to wire the ring main yourself, make sure the power supply is off and use caution to reduce hazards whilst working.
What is a ring final circuit?
A ring final circuit is the correct term for a ring main. A ring circuit is also the same thing.
How many sockets on a 32A ring main?
There is no limit on how many sockets you can install on a 32-amp ring main. However, the maximum load for a circuit at any given time should be 7,500 watts. Thus, while the number of sockets is not limited, the number of appliances and electronic devices you use at the same time could be limited.
How many spurs are allowed on a ring main?
Spurs are often added to circuits to run electricity to additional sockets or appliances, such as the cooker hood.
The number of spurs on a circuit is limited to the number of sockets. You can install a maximum of one spur per socket.
Wiring a ring main isn’t difficult, but you must ensure that your circuit complies with British standards and regulations. We hope this guide can help you install the circuit yourself.
However, remember that having it wired by a qualified electrician is the simplest, most effective way of complying with the law and preventing potentially life-threatening domestic accidents.