General
Number of conductors	2 Conductor
Terminal type	Through-wiring clamp -
Cross section	0,08-4 mm²
Colour	Blue -
Application range	Ex i -
Mounting base	Support rail -
Approval	Ex i -
Construction type	Through-wiring clamp -
Marking	Blue -
Connection cross section	0,08-4 mm²

The WAGO 281-904 is a 2-conductor pass-through terminal block in blue finish, specifically designed for applications in the Ex i (intrinsically safe) category. This terminal block enables the secure connection of two conductors in a pass-through design, with the connection wires attached from the front. The terminal block is rated for cross-sections from 0.08 to 4 mm², making it suitable for a wide range of conductors in industrial electrical engineering. The blue color serves as a visual identifier and is commonly used in terminal block design to indicate function or application area.

Applications

The terminal block is suitable for use in explosive atmospheres, particularly in installations designed according to the Ex i protection type. This includes applications in the process industry, chemical, or petrochemical sectors, where intrinsically safe power supply is required to avoid ignition hazards. The terminal block meets the requirements for electrical safety in such environments, with exact approval and certification determined by relevant standards and certification authorities.

Functions and Equipment in Detail

The 2-conductor pass-through terminal block enables the connection of two conductors within a single component, with current flow passing through the block. The connection wires are inserted from the front, allowing for quick and secure installation. The terminal block is rated for cross-sections from 0.08 to 4 mm², offering broad application possibilities for different conductor cross-sections. The blue painted surface serves as a visual identifier and is standard in terminal block design.

Technology Explained Simply

The terminal block operates on the principle of a pass-through terminal, where the electrical connection between two conductors is established via a common contact surface. The connection wires are inserted from the front into the terminal block and secured by a screw or clamp connection. The terminal block is suitable for use in Ex i applications, meaning it can be used under specific conditions in explosive atmospheres without creating an ignition source. The exact operation of intrinsic safety is based on limiting voltage, current, and power to prevent ignition of flammable gases or vapors.

Compatibility and Accessories

The terminal block is compatible with various accessories that support its use in complex circuits. These include, for example, multilabeling systems such as the WMB multilabeling (e.g., 793-501/000-023 or 793-5501/000-006), which allow clear identification of connections. Additionally, terminal bridges (e.g., 781-453), group label holders (e.g., 209-142), and wire chain bridges (e.g., 709-112) are available to structure and optimize wiring. Installation typically occurs on standard mounting rails (e.g., 210-112 or 210-506), ensuring secure fastening.

Installation and Mounting

The terminal block is mounted on standard mounting rails with dimensions 35 x 7.5 mm or 35 x 15 mm, available in various versions (perforated, non-perforated, galvanized). The terminal block is mounted using a special holder (e.g., 209-106) or directly onto the rail. The connection wires are inserted from the front into the terminal block and secured by a screw or clamp connection. Installation requires no additional tools beyond a screwdriver or pliers, depending on the design.

Operational Advantages

The terminal block provides a reliable and secure connection for two conductors in a pass-through design. Its use in Ex i applications enables safe installation in explosive atmospheres. The clear identification via the blue color and compatibility with labeling systems such as WMB simplify maintenance and identification of connections. The robust construction and use of high-quality materials ensure long service life and high reliability in industrial use.