Connection Terminals

What types of connection terminals are there?

There are different types of connection terminals, each with specific applications and advantages. The most common are:

Wire Connectors (push-in terminals)

Wire connectors, often also called push-in terminals or Wago connectors, are a modern and highly popular choice for quickly and safely connecting wires. They usually require no tools and offer an easy "push-in" or "lever" mechanism to securely fasten the stripped wire. The transparent housing allows visual inspection of the connection, increasing safety. They are available for various wire thicknesses and types, including solid, stranded, and fine-stranded conductors, depending on the model (for example, Wago 221 series for all wire types).

Screw Terminals (chocolate blocks)

Screw terminals, also known as chocolate blocks, are the traditional method for connecting wires and consist of a plastic or ceramic housing with metal clamps that secure the wires using small screws. Although widely known, they are nowadays less recommended for permanent installations, especially with solid core wire. However, they are still usable for stranded wires, for example when connecting a lamp, provided a ferrule is used to avoid fraying. Multiple wires under one screw is unsafe and should be avoided.

Screw Clamps

Screw clamps are robust terminals where a screw directly clamps the wire. These provide a very strong connection and are suitable for high currents and larger cross-sections. They require firm tightening with appropriate tools and may need periodic checking in environments with many vibrations.

What should you pay attention to when using connection terminals?

Correct installation of connection terminals is crucial for the safety and reliability of your electrical installation.

Always turn off the power

Before working on electrical wiring, it is essential to switch off the power at the main switch or the relevant circuit breaker in the meter cabinet. Check with a voltage tester to ensure the wires are voltage-free. This prevents electric shocks and short circuits.

Strip the wires correctly

Strip the insulation from the electrical wire to the recommended length for the specific terminal, usually between 9 and 13 mm. Stripping too short results in poor contact, stripping too long may cause a risk of short circuit due to exposed copper outside the connector. For stranded or fine-stranded conductors, it is advisable to use a ferrule for a better and safer connection.

Choose the right terminal for the wire type and cross-section

Not every terminal is suitable for every wire type (solid, stranded, fine-stranded) or cross-section (expressed in mm² or AWG). Always check the specifications of the terminal to make sure it is compatible with the wires you want to connect. For example, do not use standard wire connectors for stranded wires without ferrules unless the terminal is specifically designed for stranded wires.

Installation inside a suitable enclosure

Electrical connections should always be protected from external influences such as dust and moisture. According to the NEN 1010 standard, conductor connections should always take place inside a suitable junction box, flush-mounted box, cable box or another approved enclosure that meets the required IP rating (for outdoor or humid areas). It is not permitted to use exposed connection terminals outside such an enclosure.

Check the connection

After connecting the wires, gently pull the wires to check if they are securely fixed in the terminal. With transparent wire connectors, you can visually check if the stripped wire is fully inserted and no bare copper is exposed outside the connector.