Terminal Blocks

What types of terminal blocks are there?

There are various types of terminal blocks, each with specific applications and advantages. The most common ones are:

Wire Connectors (Push-in Connectors)

Wire connectors, often also called push-in connectors or Wago connectors, are a modern and highly popular choice for quickly and safely connecting wires. For most applications, they require no tools and feature a simple "push-in" or "lever" mechanism to securely hold the stripped wire in place. The transparent housing allows you to visually check the connection, enhancing safety. They are available for a wide range of wire thicknesses and types, including solid, stranded, and fine-stranded conductors, depending on the model (for example, the Wago 221 series for all wire types).

Screw Terminal Strips (Chocolate Blocks)

Screw terminal strips are the traditional connection method, consisting of a plastic or ceramic housing with metal clamps that secure the wires with screws. Although widely known, they are nowadays less recommended for permanent installations, especially with solid VD wire. However, they are still suitable for stranded wires, for example, when connecting a lamp, provided a ferrule is used to prevent fraying. Placing multiple wires under one screw is not safe and should be avoided.

Screw Clamps

Screw clamps are robust terminals in which a screw directly clamps the wire. They provide a very strong connection and are suitable for high currents and larger wire cross-sections. Proper tightening with the appropriate tool is required, and in environments with a lot of vibration, regular checks may be needed.

What should you pay attention to when using terminal blocks?

Proper installation of terminal blocks is crucial for the safety and reliability of your electrical system.

Always switch off the power

Before starting any work on electrical wiring, it is absolutely essential to switch off the power at the main switch or the relevant circuit in the fuse box. Use a voltage tester to make sure the wires are voltage-free. This prevents shocks and short circuits.

Strip the wires correctly

Strip the insulation from the electrical wire to the recommended length for the specific terminal block, usually between 9 and 13 mm. Stripping too little can result in poor contact, while stripping too much may pose 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 connector for the wire type and cross-section

Not every connector is suitable for every wire type (solid, stranded, fine-stranded) or wire cross-section (expressed in mm² or AWG). Always check the connector’s specifications to ensure compatibility with the wires to be connected. For example, do not use standard wire connectors for stranded wires without ferrules, unless the connector is specifically designed for use with stranded wires.

Install in a suitable enclosure

Electrical connections must always be protected from external influences such as dust and moisture. According to the NEN 1010 standard, conductor connections must always be made inside a suitable junction box, flush mounting box, cable box, or another approved enclosure that meets the required IP rating (for outdoor or damp environments). It is not permitted to use exposed terminal blocks outside such an enclosure.

Check the connection

After connecting the wires, gently pull on them to check whether they are firmly secured in the connector. With transparent wire connectors, you can visually check whether the stripped wire is fully inserted to its stop and that there is no bare copper visible outside the connector.