How to Select the Right Terminal Block
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Choosing the correct terminal blocks is straightforward. Just follow the steps below:
- Determine current, voltage and wire size (AWG) to be used for the individual wire runs in the control or power distribution application.
- Define any special space constraints imposed by the application.
- Considering the first two steps, select the appropriate rated feed-through terminal types to satisfy the electrical and space requirements. Select block widths. Double the block level and wire size if necessary to meet space requirements.
Figure 42. Basic Wire and Block Requirements
- Determine how many blocks (number of Poles) are needed, whether any blocks need to be jumped and how the jumper connections should be made (which plane), i.e., top — cross connector/side — jumper comb.
Figure 43. Connection Type
Cross Connector
Jumper Comb
- Select special function block (ground, disconnect, fuse, indicating types, switch) based upon application requirements.
Figure 44. Special Function Blocks
- At the end of each terminal block assembly, wherever a change in terminal block size occurs or when a side of a terminal block is not used, specify an end plate. Unused sides of terminal blocks must not be left uncovered and exposed.
Figure 45. End Plates
- Determine where isolation partitions are needed to provide visual separation or to contain creepage within the terminal assembly. To ensure safety, isolation partitions separate blocks with different amperage ratings or voltages to prevent current/voltage jumping from one to another. Partitions also indicate to maintenance crew or electricians that there may be a different voltage in each of the groupings of blocks.
Figure 46. Isolation Partitions
- For rail mounted blocks, select the type of rail for mounting. Calculate the length required by totaling the individual widths (thicknesses) of the terminal blocks, end plates, isolation partitions and end stops.
Figure 47. Rail Type
- Mark wire terminations using marking tags.
Figure 48. Marking Wire Terminations
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