Electrical Cable in Ireland

Short answer: most wiring inside an Irish house is flat twin and earth, 1.5mm² for lighting and 2.5mm² for socket circuits. Anything running outside or underground should be steel wire armoured. Cable is cut to length at the counter and is not sold through the website, so ring 01 401 9907 or email sales@shamrockelectrical.ie with the type, size and metres you need.

What cable do I need for sockets and lighting?

Lighting circuits are normally 1.5mm² twin and earth and socket circuits 2.5mm². A cooker or an immersion heater usually needs 6mm² or 10mm² depending on the load and the run.

Those are the conventional sizes, not a substitute for a calculation. The size a circuit actually needs depends on the current it carries, how long the run is, how the cable is installed, and what else it is bunched with. A 2.5mm² cable clipped to a joist in free air and the same cable buried in insulation are not the same cable in practice, because insulation stops it shedding heat.

Voltage drop is the other half of it. On a long run to a shed or an outbuilding, the cable is often sized up not for current but to keep the voltage at the far end within limits. That is a calculation, and in Ireland the design and certification of the circuit sits with a registered electrical contractor under I.S. 10101.

What is twin and earth cable?

Flat PVC cable with two insulated conductors and a bare earth conductor between them. It is the standard cable for wiring inside a house in Ireland.

The flat profile is the point. It sits into a chase in a wall, or clips flat along a joist, without the depth a round cable needs. The bare earth in the middle is sleeved in green and yellow at every termination, which is one of the commonest things to be pulled up on during an inspection.

Twin and earth is for dry, protected, indoor use. It is not suitable outdoors, buried, or anywhere it can be damaged, and PVC hardens and cracks with sustained heat and UV. If the cable is going outside, it is the wrong cable.

When do I need armoured cable?

Any run outside, underground, or anywhere the cable can take a knock. Steel wire armoured cable has a steel braid under the outer sheath that resists mechanical damage.

The usual jobs are a supply to a garage, a shed, a workshop, a garden office, gate automation or external lighting. The steel armour also gives the cable real pull strength, so it survives being drawn through a duct.

Armoured cable is terminated with a proper gland, not by cutting the armour back and hoping. The gland grips the steel braid and, where the armour is being used as the earth path, makes the electrical connection to it. Buying the cable and forgetting the glands is the classic way to lose an afternoon, so count both.

Two core armoured suits a simple single phase supply. Three core is the normal choice where a separate earth conductor is wanted rather than relying on the armour, and where a switched line is being taken out to the far end.

How deep should armoured cable be buried?

Commonly 450mm deep in a garden or a lawn, and 600mm under a driveway or anywhere vehicles cross, with warning tape laid in the trench above the cable.

Depth is about what might come along later with a spade or a digger, so the figure changes with what is above it. A flower bed that gets turned over every spring deserves more cover than a strip of lawn, and the cable should be sitting on and covered by sand or sifted soil rather than the stones that came out of the trench.

Lay the warning tape at roughly half the depth, not directly on the cable, so somebody digging meets the tape with enough ground still to go. Photograph the run before it is backfilled and keep the picture. It is worth a great deal five years later when somebody is putting in a fence post.

What are 16 amp and three phase industrial sockets for?

Blue 16 amp sockets are single phase outlets for sites, workshops and outbuildings. Red sockets are three phase, for machinery and larger fixed plant.

The colour is the voltage, and it is a safety convention rather than a style choice. Blue is 230V single phase, red is 400V three phase, and yellow is 110V, which is the reduced voltage used for tools on many Irish sites. The connectors are keyed so that a plug cannot be pushed into the wrong voltage.

These are the fittings that turn a shed or a workshop into something that will actually run a welder or a compressor. They need the cable and the protective device to match, which is where the conversation usually starts at the counter rather than ending there.

Where can I buy electrical cable in Dublin?

At the Shamrock Electrical trade counter in Greenogue Business Park, Rathcoole, just off the N7 and well positioned for the M50. Cable is cut to length at the counter.

Cable is not sold through the website. It is heavy, it is priced by the metre against the copper market rather than by a fixed shelf price, and most orders are cut to a length rather than bought as a drum. Telling us the run is faster than working out a basket.

Website prices are retail. Trade pricing on cable is set by account and by quantity, so ring the counter on 01 401 9907 or email sales@shamrockelectrical.ie with the cable type, the size in mm², and the metres you need, along with any glands or accessories.

We have been supplying Irish contractors from Rathcoole since 2016 and hold accounts with the main cable manufacturers, so a size we do not have cut on the day is usually a short order in. Ring ahead if the quantity is large or the size is unusual.

Trade counter details

Shamrock Electrical, Unit 22, Block 613, Jordanstown Road, Greenogue Business Park, Rathcoole, Co. Dublin, D24 TX98.

Phone 01 401 9907. Email sales@shamrockelectrical.ie.

Opening hours: Monday to Friday 7am to 5pm, Saturday 9am to 1:30pm, closed Sunday.