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close this bookTreatment of Lines for Mobile Devices and Appliances - Course: Basic skills and knowledge of electrical engineering. Trainees' handbook of lessons (Institut für Berufliche Entwicklung, 21 p.)
close this folder3. Connection of Lines to Mobile Devices and Appliances
View the document3.1. Making of Screw Fastenings
View the document3.2. Tension Relieving
View the document3.3. Principle Regulations for Plug-in Devices
View the document3.4. Combining of Mobile Lines to Bank Cables in Plants and Devices

3.1. Making of Screw Fastenings

- Before a cable is put in and connected to a mobile device or appliance, this cable has to be stripped according to the requirements and prepared for connection.

- With the stripping length, the arrangement of the connections in the device or appliance has to be taken into consideration.

After putting the cable into the place of connection, a protective measure with protective conductor has to be taken and the external conductors have to be cut in such way that the protective conductor is the longest connecting core.

Figure 21 Collar coupler plug

1 protective conductor,
2 tension relieving

Why shall the protective conductor be the longest connecting core in the place of connection of the device or appliance?


- The covering of the cable must project into the device or appliance for approximately 3 mm.

By putting in the covered cables, the conductor insulation cannot be damaged by perhaps sharp edges of the device or appliance and sources of faults are avoided.

- The core insulation must end 1 mm in front of the connecting point.

Figure 22 Connection points with correctly removed core insulation

Securing under terminals of the core insulation would put the functioning of the connection at risk. Too long stripping could lead to short circuits.

- Conductors equipped with eyes must only be connected in the direction of rotation of the terminal screw. (In doing so, make sure that the eye rests evenly on the junction block, because otherwise it may come to a deficiency of contact.)

- If several conductors are connected to one connecting bolt, pay attention that each conductor is followed by one washer and that - at least after every third conductor - one spring ring is inserted.

- If and when cable thimble and eye are connected to one connection bolt, the eye has to be connected separately.

Figure 23 Connection to a connection bolt

1 cable eyes, 2 conductor with eyes, 3 connection bolt, 4 washers, 5 spring ring

- With the connection of protective conductor and middle wire, only one conductor per connecting point is permissible.

- To cap-screws without clamping bow or conductor holding fixture, three conductors which may differ by two cross-section steps at the most are allowed to be connected only if one washer is placed between the conductors, each.

Figure 24 Connection by a cap-screw without clamping bow and holding fixture to a connection strap

1 connection strap,
2 conductor

- To cap-screws with clamping bow only one conductor is allowed to be connected on either side of the bow. The conductors to be connected may differ by one step in cross-section.

Figure 25 Connection to a cap-screw with clamping bow

1 clamping bow

- To cap-screws with conductor holding fixtures only one conductor is allowed to be connected to each holding fixture. The conductors to be connected must have the same cross-sections.

Figure 26 Connection to cap-screw with holding fixture

1 free disk, 2 conductor holding fixture

The washers used for the connection of conductors to screws or bolts must cover at least 2/3 of the conductor.

Screw slots must not be damaged by using wrong or defective screw drivers.

- To terminal blocks for sequencing two conductors are allowed to be connected to each terminal point, if they are soldered together at the connecting points and equipped with conductor end sleeves.

- When connecting conductors with end sleeves or eyes, make sure that

. the clip of each respective contact is sufficiently fastened, so that the conductor cannot the sleeve or eye,

. if the conductor end sleeve might be shifted on the conductor when it is put in the clip - for instance with cables that are put in from above - the sleeve should be slightly pressed on with the help of a suitable tool such as round-nose pliers or side cutting pliers.