General
Terminal type	three-tier terminal -
Function	protective earth terminal PE -
Bridging	internally bridged -
Colour	Green-yellow -
Conductor cross section	0,08-2,5 mm²
Maximum conductor cross-section	4 mm²
Number of conductors	6 -
Mounting	DIN rail 35 x 15 mm and 35 x 7.5 mm -
System	CAGE CLAMP® -
Current loading	18 A
Label carrier	None -

The WAGO 870-557 is a three-level terminal block designed for use as a protective earth (PE) terminal block in industrial and commercial electrical applications. It is specifically designed for connecting protective conductors and enables the safe and reliable connection of up to six conductors with a cross-section of 0.08 to 2.5 mm² (limited use is possible with 4 mm²). The terminal block is internally bridged, ensuring all connected conductors are electrically interconnected without requiring additional bridges. The green-yellow color identifies its function as a protective earth terminal block in accordance with international standards. The terminal block is supplied without a label carrier, allowing flexible integration into existing installations.

Applications
This terminal block is intended for use in enclosures, distribution boxes, and other electrical installations where a secure and durable connection of protective conductors is required. It is particularly suitable for applications in industrial automation, building electrical engineering, and power engineering. It is used in systems mounted on standard support rails of 35 x 15 mm or 35 x 7.5 mm, enabling standardization and easy integration into existing enclosure constructions.

Functions and Features in Detail
The terminal block features the CAGE CLAMP® system, enabling quick and secure connections without tools. The principle relies on a clamp lever that automatically establishes contact when pressure is applied to the conductor. The terminal block is designed for conductor cross-sections from 0.08 to 2.5 mm², with limited use possible for 4 mm². The internal bridging ensures all connected conductors are electrically connected, simplifying installation and increasing reliability. The green-yellow color visually identifies its function as a protective earth terminal block.

Technical Explanation
The CAGE CLAMP® system operates without tools: the conductor is inserted into the clamp channel, and the clamp lever is actuated by pressure, automatically securing the conductor. The terminal block is rated for a maximum current load of 18 A, which is sufficient for typical protective conductor applications. The internal bridging is achieved through a fixed electrical connection within the terminal block, eliminating the need for additional bridges or connections. The terminal block is designed for mounting on standard support rails (35 x 15 mm and 35 x 7.5 mm), enabling universal use in various enclosure systems.

Compatibility and Accessories
The terminal block is compatible with various accessories that extend its functionality. These include comb bridges such as 870-439 (1 to 9) or 870-433 (1 to 3), which enable connections between multiple terminals. Labeling systems such as the WMB multilabel system (e.g., 793-5501/000-006) or labeling strips (e.g., 709-178) can be used to identify the terminals. Additionally, end plates (e.g., 870-569, 870-568) and plug-in extraction modules (e.g., 870-425) are available to facilitate mounting and maintenance. Support rails such as 210-506 (35x15 mm) or 210-504 (35x7.5 mm) are also compatible and allow mounting of the terminal block in enclosures.

Mounting and Installation
Mounting is performed on standard support rails with dimensions 35 x 15 mm or 35 x 7.5 mm. The terminal block is simply clipped onto the rail and locks automatically. Conductor connections are made via the CAGE CLAMP® system: the conductor is inserted into the clamp channel, and the clamp lever is actuated to secure the conductor. The internal bridging ensures all connected conductors are electrically interconnected. The terminal block is supplied without a label carrier, allowing an external labeling system to be used if required.

Operational Advantages
The terminal block provides a fast and secure connection without tools, reducing installation time. The internal bridging reduces the number of required connections and increases circuit reliability. The green-yellow color provides clear visual identification as a protective earth terminal block. Compatibility with standard support rails and various accessories enables flexible and universal use across different application areas. The terminal block is designed for use in industrial and commercial installations, with a maximum current load of 18 A sufficient for typical protective conductor applications.