The changing wire termination requirements of OEMs and Panel Builders have led to the following terminal block trends.
•Increased usage of screwless connections to reduce installation times
  - Spring Loaded terminals
  - Push-in terminals
  - Insulation Displacement connections
•Multi-function terminals
•Common accessories to reduce inventory and allow for shorter parts listsCommon accessories to reduce inventory and allow for shorter parts lists

Terminal Blocks with Spring Loaded Connections

Spring loaded terminals allow for faster connection of wires than traditional screw terminals.  The other advantage of the spring loaded connection is that the spring exerts constant pressure on the conductor.  Even in high vibration applications, there is no need to conduct periodic checks of the connection.

Operation:  The spring loaded clamp is opened by inserting a screw driver.  A stripped conductor is then inserted as far as possible into the spring clamp.  When the screw driver is removed, the conductor is held in place by the clamp.  Solid, stranded or finely stranded conductors can be easily and permanently clamped.

The Siemens 8WH2 line of spring loaded terminal blocks have extremely compact designs which ensure user-friendly wiring even where space is at a premium.  Connections are made from the top of the terminal block so the conductors are securely connected to the power bus.  Versions are available for conductor sizes 28 AWG (1.5 mm2) through 2 AWG (35 mm2).

Terminal Blocks with Insulation Displacement Connections (IDC)

Insulation Displacement terminals allow for faster connection of wires than Spring Loaded terminals.  Since it is not necessary to strip the conductor, installation time savings of up to 60% can be achieved.

Operation:  Both a screw driver and a conductor are inserted into their respective guides on the terminal block.  When the screwdriver is pushed forward, the Insulation Displacement Clamp cuts into the conductor insulation on two sides making contact with the wire.  This establishes a secure contact with the wire.

The Siemens 8WH3 line of insulation displacement terminal blocks is intended for use in applications where installation time savings are critical and cover conductor sizes 24 AWG (1.5mm2) through 14 AWG (2.5mm2).

Terminal Blocks with Plug-in Connections

Terminal Blocks s with Plug-in Connections allow for the fastest possible installation of stripped solid conductors or stranded conductors with end sleeves.  The plug-in connection is particularly advantageous in very narrow or tight wiring applications.

Operation:  Solid conductors or conductors with end sleeves are simply pushed into the wire guide of the terminal block.  A screwdriver is only used to remove the conductor from the terminal block.  This is the same wiring technology that is used to wire residential wall switches and plug-in receptacles.

The Siemens 8WH4 line of plug-in terminal blocks covers conductor sizes from 24 AWG (1.5 mm2) through 8 AWG (6 mm2).

Terminal Blocks with Combination Plug-in Connections

Combination Plug-in terminals are used any where pre-assembled modules are used or a high degree of modularity is needed.  This is an excellent choice for OEMs who want to create wiring harnesses or standardize on the fastest possible connection types, but still allow end-customers to wire to traditional screw terminals.

Operation:  This contact system consists of two parts; terminal block and plug.  The plug is wired separately from the terminal block and at final assembly the plug is “plugged into” the terminal block.  Both the plug and terminal block use familiar screw or spring loaded connections and can withstand the most extreme vibration demands.

The Siemens 8WH4 line of Combination Plug-in terminal blocks include a finger safe design to prevent human contact with live electrical parts and cover conductor sizes from 22 AWG (0.25 mm2) through 10 AWG (12 mm2).

Whether you require traditional screw terminals or want to improve your wiring efficiency with an alternate termination type, the Siemens ALPHAFIX family of terminal blocks can meet your needs.