How to connect a double socket? A practical guide for beginners

Added: Monday, 3/3/2025


Are you wondering how to connect a double socket without damaging the electrical system and… surviving? Don't worry, connecting a double socket yourself is not a complicated task – even for a novice DIYer. The process is basically the same as connecting a single electrical socket and does not require the use of many tools. Use our tips to efficiently and safely install your first electrical socket.

An electrician installing an electrical socket

How do I connect cables to a double socket?

Correctly connecting the wires is a key stage of the work. It determines whether the socket will work at all. It is most convenient to carry out the work in daylight. Start by turning off the power in a specific socket or in the entire house/apartment. In the case of a new electrical installation, simply turn off the fuse using the lever. Just in case, check whether the socket is definitely not flowing. A voltage tester will help you with this or connect a working electrical device and check whether it turns on.

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Are you sure the socket is not live? You can safely remove the old electrical socket. All you need is a screwdriver. After removing the metal box, you will see the cables screwed to it. Take a picture with your phone so that you don't have to remember the arrangement of the cables when installing the new socket.

Connecting electrical sockets is different for grounded and ungrounded contacts. If you connect a double socket without grounding (pin), you will only operate with two wires: phase and neutral. You connect the phase wire on the left and the neutral wire on the right. Most often, grounded installation sockets are chosen for electrical installations. A double electrical socket with a pin (grounding) requires connecting three wires. Each has a different color:

  • the phase (voltage) wire is brown or black - connect it to the left L terminal,
  • the neutral wire (neutral) is blue - connect it to the right N terminal,
  • the protective (grounding) wire is yellow-green - mount it to the PE center terminal (pin).

You will usually find the appropriate markings on the terminals. If it turns out that the cable ends are too short, use pliers to strip the insulation. Then mount the wires in the terminal or tighten them using screws.

Once the wires are connected correctly, you can place the inner part of the electrical socket in the wall box and screw it in place. When inserting the socket into the box, be careful not to damage the wires with the hooks. Once the box is in the correct position, you can mount the socket cover. Ready? Turn on the power and check that there is voltage in both sockets, e.g. using a tester or by connecting any two electrical devices to a double socket.

Something went wrong? Make sure the wires are connected correctly and that they have not fallen out of the terminals. Is there still no voltage in the sockets? For the safety of the household, the appliances and the entire installation, it is worth contacting an electrician.

Double electrical socket

How many cables are needed for a double socket?

As we mentioned at the beginning, double electrical sockets are installed in a similar way to single models. They therefore require the connection of three cables, as a rule: a phase (voltage) wire, a neutral (zero) wire, and a grounding (protective) wire. The vast majority of electrical sockets installed today have grounding, i.e. a characteristic pin.

Which side is the phase on in a double socket?

The phase wire is always on the left - both in the lower and upper electrical outlets.

We encourage professionals from the electrical industry and individual customers to familiarize themselves with the offer of the Onninen wholesaler. In our assortment you will find over 2,000 electrical sockets - single, double, triple and quadruple. We build the offer based on electrical installation equipment from leading Polish and foreign manufacturers. Onninen specialists provide technical support.

Check out the offer of electrical sockets at the Onninen wholesaler