Direct contact between copper and aluminum in a junction box causes instant galvanic corrosion, causing heating and failure of the connection. It was designed to prevent such emergencies. spring clamp, which became the basis for the design of all connectors Wago. Unlike traditional twisting, where the quality of contact depends on the strength of the installer’s hands, here the force is created by a mechanically calibrated stainless steel spring. This device provides constant pressure on the wire cores, compensating for the thermal expansion of the metal and preventing the contact from weakening over time.
The operating principle is based on the use of elastic deformation energy of a special spring, which presses the conductor to the contact pad. When you insert the stripped core into the housing, it passes through the guide funnel and rests against the end of the spring element. Further advance pushes the coils apart or deflects the plate, creating a powerful return force. This force ensures that even under vibrations common to automotive wiring or industrial machines, the connection remains tight and reliable.
Design and device of spring clamp
The heart of any connector is contact group, made of phosphor bronze or tinned copper. This material was not chosen by chance: it has high electrical conductivity and corrosion resistance. The spring that creates pressure is made of chromium-nickel steel, which does not lose its elastic properties even after thousands of compression and stretching cycles. The body of the product is made of polyamide, which does not support combustion and can withstand short-term exposure to high temperatures up to 200 degrees Celsius.
Inside the housing there is a special chamber into which the conductor is inserted. The geometry of this chamber is designed to ensure centering of the core and correct distribution of the clamping force. It is critical that the spring pressure is directed perpendicular to the axis of the wire, which eliminates its damage or breaking of individual current-carrying threads. This design allows you to connect both solid and stranded wires without the use of additional lugs (with the exception of some specific series).
- 🔌 Contact lamella - the main conductive element that transmits electric current.
- 🔩 Spring block — creates and maintains constant clamping force.
- 🛡️ Insulating housing — protects against electric shock and external influences.
Locking mechanism: PUSH-IN and lever clamp
There are two main mechanisms for fixing wires, which implement the principle of operation in different ways. The first type is technology PUSH-IN, characteristic of the 773 and 2273 series. Here the wire is inserted with force until it stops, after which the spring automatically snaps into place, securely fixing the core. It is possible to remove the conductor from such a connection only with rotational-translational movements, which makes it ideal for permanent connections that are not planned to be disconnected in the future.
The second type is the famous one lever mechanism, used in the 221 and 222 series. In this case, the spring is initially locked by a plastic lever in the closed position. To connect, you need to pull the lever up, which opens access to the contact chamber and releases the spring. After inserting the wire, the lever returns to its original position, and the spring clamps the wire with force. This allows installation and dismantling to be carried out multiple times without loss of contact characteristics.
Lever connectors Wago The 221 series is considered a universal standard due to its transparency and convenience. The lever has a clear stroke and locks securely in both positions. Visual inspection through the transparent body allows you to make sure that the wire has entered to a sufficient depth and that the insulation has not entered the contact area. This significantly reduces the risk of defects when installing electrical wiring.
Comparison with traditional twisted and screw terminals
Traditional wire twisting, even when done by a professional, is susceptible to oxidation and loosening due to temperature cycles. The metal expands when heated and contracts when cooled, which over time leads to the appearance of gaps and an increase in contact resistance. At the point of poor contact, heating begins, which accelerates oxidation, creating a vicious circle leading to a fire. The spring clamp does not have this drawback, since the compression force is constant and does not depend on the ambient temperature.
Screw terminal blocks, in turn, require periodic tightening. Vibration present in electrical panels and cars gradually loosens the screw. In addition, the sharp edge of the screw can damage the stranded wire strands, reducing the cross-sectional area and creating a localized hot spot. Terminals Wago ensure uniform fit over the entire contact area without damaging the metal structure.
| Parameter | Twist | Screw terminal | Wago terminal |
|---|---|---|---|
| Contact reliability | Low (oxidizes) | Medium (needs tightening) | High (constant effort) |
| Installation speed | Low | Average | High (seconds) |
| Cu+Al connection | Prohibited | Possibly (with pasta) | Possibly (with pasta) |
| Vibration resistance | Low | Low | High |
The main advantage of spring terminals is that the quality of contact is independent of the qualifications of the installer and operating conditions.
Connecting dissimilar metals: copper and aluminum
One of the most common problems with old wiring is the need to connect copper and aluminum wires. Direct contact of these metals is strictly prohibited due to the difference in electrochemical potentials, which leads to the rapid destruction of aluminum. In connectors Wago this problem is solved constructively: the contact pads are made of tinned copper, and a special one is used to connect dissimilar metals contact paste.
This paste is located inside the terminals (series 2273, 773) or applied separately (in lever series). It displaces air and moisture from the contact zone, preventing oxidation. The paste envelops the aluminum core, creating a protective film, and ensures a stable transition of electric current without electrochemical corrosion. This makes it possible to safely expand wiring or connect new lines in old houses.
⚠️ Attention: When using terminals without factory paste to connect aluminum to copper, you must independently treat the contact surfaces with quartz-vaseline paste. Ignoring this rule will lead to oxidation of the contact.
Technical characteristics and current loads
Each series of connectors has its own limitations on current and wire cross-section. For example, the 2273 series compact terminals are designed to work with cross-sections up to 2.5 mm² and withstand currents up to 24 Amps. The larger 221 series lever terminals are also rated for up to 32 Amps in cross-sections up to 4 mm². Exceeding these parameters will lead to overheating and melting of the case, so the choice of model must strictly correspond to the electrical network design.
An important parameter is also the operating voltage. Standard household terminals are designed for 400-450 Volts, which covers the needs of conventional 220V networks with a margin. However, for 380V industrial networks or systems with possible voltage surges, it is necessary to select models with the appropriate markings. Ambient temperature also affects the current carrying capacity: if the temperature rises above 60°C, the maximum current may be reduced.
To check the reliability of the connection, use a thermal imager or pyrometer 30 minutes after turning on the full load. The temperature of the terminal should not exceed the temperature of the wires.
Typical errors during installation and operation
Despite the ease of use, installers often make mistakes that negate the benefits of the technology. The most common of these is insufficient stripping of the insulation. If the wire is stripped too short, it does not reach the contact area and there is effectively no connection. If it is too long, the exposed part may stick out, creating a risk of short circuit. The optimal stripping length is indicated on the housing of each terminal (usually 9-11 mm).
Another mistake is trying to stuff a wire with residual oxides or old insulation into the terminal. The contact group should only touch clean metal. It is also not recommended to use lever terminals to secure wires under constant mechanical load (for example, if the wire is under tension). Although the spring holds tightly, the constant pulling force can lead to gradual extrusion of the core.
- ❌ Use of 773 series (PUSH-IN) terminals for stranded flexible wires without ferrules.
- ❌ Exceeding the number of connected wires (you cannot insert two wires into one socket if this is not provided for by the design).
- ❌ Ignoring color markings and phasing when assembling the circuit.
⚠️ Attention: Never use damaged terminals with cracked housing or deformed arms. Violation of the seal of the housing can lead to moisture and dust getting inside the contact group.
How to check the authenticity of Wago?
The original terminals are clearly marked, the WAGO logo cannot be erased with a finger, the plastic is matte and of high quality. There are often stripping instructions on the side. Counterfeits are often made of glossy plastic, have a pungent odor and play in the lever.
FAQ: Frequently asked questions
Is it possible to bury Wago terminals in the wall?
Yes, you can, but only if they are inside a distribution box with access (lid). Bricking them directly into plaster or concrete without the possibility of maintenance is prohibited by the rules of the PUE, since any connection requires periodic inspection.
Will Wago terminals withstand the load from a welding machine?
No. Household terminals are designed for currents up to 32A. Welding machines consume significantly more in peak modes, which will lead to melting of the contact. For such purposes, special industrial terminal blocks or bolted connections are used.
How many times can a lever terminal be used?
The manufacturer claims multiple connection/disconnection cycles. Practice shows that the lever can withstand 10-15 cycles without loss of spring elasticity, after which the reliability of fixation may decrease.
Do I need to insulate the Wago terminals additionally?
The terminals themselves have the necessary insulation. However, if they are used outside of a junction box or in a humid/dusty environment, it is recommended to additionally insulate the connection with heat shrink or electrical tape to protect it from external factors.
☑️ Pre-installation checklist
Understanding How the Connection Terminal Works Wago, allows you not just to mechanically twist wires, but to create safe and durable electrical connections. The correct choice of series, adherence to installation technology and consideration of current loads guarantee the absence of problems with electrical wiring for decades. Using modern technology in electrical installation is an investment in the safety of your home or car.