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Handbook of Electrical Installation Practice - BeKnowledge

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Mains Cables 523<br />

Fig. 19.8 Outdoor termination with cold shrink protection for 11kV polymeric- and paperinsulated<br />

cables (Pirelli Cables Ltd).<br />

the pouring must ensure that no air bubbles exist as these become potential breakdown<br />

areas. Adhesion to the cable sheaths is essential to prevent the entry <strong>of</strong> moisture<br />

and, in addition with polymeric m.v. cables, good adhesion to the core insulation<br />

is essential to avoid introducing a breakdown path under the influence <strong>of</strong> lightning<br />

impulse voltages. Figure 19.9 shows a typical pr<strong>of</strong>ile <strong>of</strong> a modern straight-through<br />

joint in an 11kV polymeric insulated cable.<br />

Low voltage polymeric cables having EPR, XLPE and PVC insulation can have<br />

their outer coverings just trimmed back for sufficient distance to ensure no surface<br />

tracking at terminations and there is no need for the ends <strong>of</strong> the cores to be enclosed<br />

in any sort <strong>of</strong> compound in normal dry situations. At joints for these l.v. cables it<br />

is necessary to seal the jointed cores from ingress <strong>of</strong> moisture from the ground in<br />

the case <strong>of</strong> buried joints and the usual manner is to enclose the whole joint in

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