Selection and Use of Terminal Block Jumpers

We find DIN rail mounted terminal blocks in nearly every industrial control panel. In this short article, we focus on the jumpers that may be used to link multiple blocks together. This provides a convenient way to expand the number of wires attached to a single node. This is particularly useful for power distribution in low current applications.

Terminal blocks organized by families of related components

Let’s begin by recognizing that manufacturers offer “families” of terminal blocks with components designed to seamlessly work together. Each ecosystem includes the blocks themselves, end plates, partition plates, end stops, jumpers, and labels. The terminal blocks may feature screw-terminal or spring-loaded connections. The jumpers may also be screw-terminal or spring-loaded. Multiple colors allow you to color code your control panel. For example, the Altech Corporation product shown in Figure 1 features the CY2.5 screw-terminal wire connections, spring loaded 4-position jumpers, and is blue in color.

Figure 1: Picture of terminal blocks with 4-position jumpers configured for power distribution with 8 connection points per node.

Jumpers electrical connect adjacent blocks

The configuration shown in Figure 1 provides a good solution for power distribution. In total, there are 8 terminal blocks. With the orange jumpers installed, they effectively form a pair of blocks, with each block having 8 available connection points. The wires enter from the sides as suggested in Figure 2. Here we can see the side-to-side bus bar. We can also just make out the wire-tensioning screws and clamps.

Figure 2: Side-by-side picture of the terminal block and jumper.

Figure 2 shows the orange spring-loaded jumper next to the terminal block. The jumper’s relationship with the bus bar is shown in the Figure-3 close-up picture. The jumper’s spring tension provides a solid electrical connection to the bus bar.

Tech Tip: Be sure to review the manufacturer’s data to determine the maximum current rating for both the terminal block and the jumper as the ratings may be different. In this example, the screw tensioned clamp and large busbar provides a low resistance. This provides a 20 or 24 A current rating depending upon which agency is doing the approval. The jumper is not expected to provide the same rating. In this case, it may be better to use a purpose-built distribution block. This can provide a high current one-to-many solution.

Figure 3: Close up picture showing the jumper anchored in the terminal block’s bus bar.

As previously mentioned, it’s important to locate the datasheet for the terminal blocks as there is a wealth of information about the component. You will also find part numbers for the related devices. Figure 4 presents part of the Altech CY2.5 series terminal blocks. The table includes all of the colors and accessories. It also includes data related to terminal blocks such as the CY6 which can handle up to 50 A.

Figure 4: Table identifying the core components and accessories for the Altech CY2.5 series.

Figure 4: Table identifying the core components and accessories for the Altech CY2.5 series.


Please leave your comments and suggestions below. Your success or challenges with terminal blocks and their associated jumpers is especially welcomed.

Best Wishes,


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