5.3 Shields for Lines Between Screened Buildings

In chapter 4.1.3.1.6 (Figure 4.1.3.1.6 a) it was shown how two spatially separated lightning protection zones can be changed into a single lightning protection zone by means of a line shield. The shields used will be introduced here as follows:

• Shielding of cables in metal conduits or closed trays which are connected on both sides at the building input (Figures 5.3 a and b).

• Use of buried cables with conductive shield which will be connected at the building input (Figures 5.3 c and d). For protection against direct lightning strikes it may be useful to incorporate superimposed earth ropes.

• Erection of cage-shaped reinforced cable ducts, if a multitude of conventional cables (e.g., between two buildings) is laid (Figures 5.3 e and f). This cable duct reinforcement must be bonded to the building reinforcement.

Figure 5.3 a: Shielding of cables in metal conduits or closed trays

Figure 5.3 b: Steel conduits and metal pull boxes form a closed line screen

Figure 5.3 c: Shielding of underground cable routes by conductive screens and surface laid copper-ropes

Figure 5.3 d: Cable with external 'lightning protection' screen, core pair screen and pairing

Figure 5.3 e: Screening of underground cable routes by cages

Expansion joints in continuously reinforced cable ducts must be bridged analogously to the building expansion joints. Similarly, duct connectors underneath or between adjacent buildings must be bridged. Also, with regard to cable ducts, it must be ensured that the maximum admissible voltage loadings on...