DIN rail terminal blocks are available with a variety of specifications for different uses. Their compact size gives them a significant degree of versatility; they can be deployed even when space is limited. However, for truly small-scale work, look for miniature and even micro-miniature variations.
Some models feature one or more fuses in a special hinged section for additional protection against overcurrent, making them a good choice for use with sensitive equipment like sensors and relays. Fuses are standard components that protect against electrical surges with a component that melts when exposed to excess current, breaking the circuit. These models often feature an LED to indicate when the fuse has blown. You may see such models referred to as DIN rail fuse holder terminal blocks.
Varying current ratings are indicated by colour coding on some models.
DIN rail terminal blocks are also distinguished by their levels. A single-level model has a single wire connection - also known as a single feed through. By contrast, a dual-level model has two connections - one above the other. The second set of wiring effectively functions as a second terminal block, in more or less the same space as a single feed model. These are sometimes referred to as double density terminal blocks.
Triple and quadruple level models are also available, along with high-end eight and 16-level options.
Termination type is another frequently used classification method. Screw terminal blocks are a common, general-purpose model. These use a clamp to secure wiring, where a screw is inserted to tighten this, pressing the wire into place. In some models, the clamp is spring-loaded, providing a more secure connection resistant to vibration.
Ring terminal blocks can be deployed more quickly because they feature preinstalled nuts that are ready to be tightened without removal first. These are also known as plug-in or push-in terminals because the wires can simply be pushed into the connection gaps.
Typically smaller than standard DIN rail terminal blocks, ring terminal blocks save space. They are usually four-level models, meaning that four wires can be connected through the block.
Earth terminal blocks are a third type. Also known as ground terminal blocks, these are used with wiring that requires direct earthing (connecting to the ground to discharge excess electrical charge). They typically feature green and yellow housing and can be mounted onto DIN rails, with the wiring secured via screws or clamps.