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Practical tips 23 February 2021
Practical Tips for Our Rail-Mount Terminal Block Systems

We’ve compiled helpful information for the correct handling of WAGO rail-mount terminal blocks. Here you’ll find answers to frequently asked questions on topics such as connecting/wiring terminals blocks, marking, commoning and official requirements.

Practical Tips:

Practical Tips for TOPJOB®S Multilevel Installation Terminal Blocks

How does wiring with multilevel installation terminal blocks work in control cabinets? What needs to be taken into account for installation and commissioning?

More Room in Control Cabinets with Multilevel Installation Terminal Blocks

Modern building installations are becoming more and more complex, and to save time and costs, distribution cabinets are being more and more densely packed with installation devices and terminal blocks. To keep things organized, WAGO’s practical marking strips are recommended when TOPJOB® S Multilevel Installation Terminal Blocks are used.
The CAGE CLAMP® connection with WAGO’s push-in connection technology makes wiring easy:
  • Solid and fine-stranded conductors with ferrules can be connected by simply pushing them in – quickly and without tools.
  • All other conductor types can be connected easily and safely by first opening the clamp.
  • After insertion, the operating tool keeps the conductor entry open and marks the clamping point, leaving both hands-free for wiring.
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Tip: Save Time during Mounting and Operation

Building installation places high demands on rail-mount terminal block systems. In addition to installation and commissioning, it must also be possible to perform regular testing quickly, safely and easily. When WAGO’s multilevel installation terminal blocks are used, insulation resistance can be measured without disconnecting the conductors, as required by standards.

Fast, Safe Installation Thanks to TOPJOB® S Multilevel Installation Terminal Blocks

WAGO’s TOPJOB® S Multilevel Installation Terminal Blocks guarantee fast, safe building installation because they are designed for space-saving wiring applications in standard distribution cabinets. Extremely compact dimensions, like the short installation length, provide maximum space for conductor termination. Featuring a large cross-section range from 0.25 to 6 mm2 (22–4 AWG), these terminal blocks cover all application areas of modern building installations.

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In combination with 1 mm (0.039 inch) thick end and intermediate plates, carrier terminal blocks can also be used with fuse plugs.

Thanks to spring pressure connection technology, these terminal blocks facilitate push-in termination of solid conductors and fine-stranded conductors with ferrules. Because only solid conductors are permitted to be used for wiring electrical circuits in building installations, the multilevel installation terminal blocks offer enormous time benefits for connection. The easily accessible, perfectly angled conductor entry ensures that conductors can be securely inserted at a convenient angle. Retightening screws during system operation is a thing of the past. Potential errors such as over-tightening screws are also eliminated. The TOPJOB® S Rail-Mount Terminal Block System also provides clear organization of the electrical circuit wiring in the distribution cabinet, thanks to the clear association of conductors to each clamping unit, as well as the easily visible terminal block marking for all levels. Marking strips affixed on the upper terminal block level allow marking with up to three lines and are not concealed by the connected conductors – even when wired. With the comprehensive, practical TOPJOB® S Jumper System, you can handle every conceivable commoning task. For example, the adjacent jumper for continuous commoning provides unlimited potential multiplication in a single jumper slot.

Correct, Fast, Standards-Compliant Insulation Resistance Measurement

After installation, the regular tests are performed. Standards DIN VDE 0100-718 and DIN VDE 0100-482 specify that it must be possible to measure the insulation resistance to ground for each outgoing circuit for conductors smaller than 10 mm2 (8 AWG) without disconnecting the neutral conductor. Measurements can only be taken correctly in accordance with the standards when one wire per clamping unit is connected. Because this is exactly what the product standards for rail-mount terminal blocks with spring clamp technology provide, you are always on the safe side with WAGO’s TOPJOB® S Multilevel Installation Terminal Blocks. As soon as two conductors are connected in just one clamping unit, which is permitted for use with screw-clamp terminal blocks and other cases, no standards-compliant insulation resistance measurements can be taken. This is because one wire must be disconnected, which is not permitted.

Multilevel Installation Terminal Blocks Become Fuse Terminal Blocks

Multilevel installation terminal blocks with internal disconnection complete the TOPJOB® S program for building installation and allow economical wiring of smaller circuit groups. The carrier terminal blocks of these new variants can also be used as fuse disconnect terminal blocks. The TOPJOB® S Fuse Plug for microfuses (5 x 20 mm) can be used in the carrier terminal block slot. The new 1 mm (0.039 in) thick end and intermediate plate adapts the terminal block width to the fuse plug width. The DIN-rail-centered slot is ideal for applications in small distribution cabinets. Fuses can be easily checked and replaced via the standard cover cut-out.

Multilevel Installation Terminal Blocks – the Economical, Future-Proof Choice

Multilevel installation terminal blocks guarantee that insulation resistance measurement complies with standards, which will grow in importance for the future, for example due to E-CHECK. Terminal blocks with push-in connection technology guarantee economical, permanently reliable installation. The clearly visible structure and legible marking provide explicit identification of the electrical circuits. This provides the best foundation for permanently reliable operation of electrical equipment.

Tip: Multilevel Installation Terminal Blocks with N-Disconnect – Sure, But Which Ones?

From a technological standpoint, buildings must be completely safe. In addition to thorough structure analysis and proper implementation, the electrical installation plays a particularly critical role. One safety measure is the insulation resistance measurement performed at commissioning and during regularly repeated tests.
This test is mandatory in fire-prone locations according to building code DIN VDE 0100-482 and for public buildings according to DIN VDE 0100-718. This standard specifies that it must be possible to measure the insulation resistance of all conductors to ground for each outgoing circuit for conductor cross-sections less than 10 mm2 (8 AWG) without disconnecting the neutral conductor. The N-disconnect is required.
Installation terminal blocks with N-disconnect are a recognized solution for meeting these demands.

Alternative 1:
Multilevel installation terminal blocks with N-disconnect slide links for mounting with N-busbar

Alternative 2:
Multilevel installation terminal blocks with internal N-disconnection for mounting without N-busbar

The state-of-the-art TOPJOB® S Rail-Mount Terminal Block System from WAGO offers two alternatives for building installation:

  • With N-disconnect slide link: 2003-76xx for cross-sections from 0.25 mm2 to 4 mm2 (24–12 AWG), 32 A

  • With N-disconnect slide link: 2005-76xx for cross-sections from 0.5 mm2 to 6 mm2 (20–10 AWG), 32 A

  • With internal disconnect: 2003-66xx for cross-sections from 0.25 mm2 to 4 mm2 (24–12 AWG), 25 or 28 A

More about TOPJOB® S

Which connector should be used, and when?

The number of individual electrical circuits that can be protected by one RCD switch must be established separately for each installation. Likewise, the installer can select from the two possible installation setups. Which of these terminal blocks should be used for installation is determined by this number.
The multilevel installation terminal blocks with N-disconnect slide link are ideal for the electrical installation of larger electrical circuit groups with only a few RCD potentials. The N-busbar can be automatically and permanently connected by simply pushing on the screwless N-disconnect slide link. This approach cuts down on wiring; the N-conductor is only supplied once per RCD potential and distributed via the N-busbar.
The multilevel installation terminal blocks with internal disconnect, in contrast, are suitable for smaller circuit groups with multiple RCD potentials.
The advantage of this alternative is that it saves space on the DIN-rail by omitting busbars. Since no short N-busbar sections for numerous different ground fault potentials are needed, installation effort is also reduced.