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Summary The mechanism of how and when an arcing short or a physical short occurs on a polyvinyl chloride (PVC)‐insulated cable when exposed to radiant heat flux has been found experimentally. How this mechanism acts on the size of the resulting arc beads is also considered. As a physical short usually changes into an arcing short in an instant, it is difficult to determine which type of short circuit occurs as the first phenomenon. To solve this difficulty, a short circuit current was limited to the order of an ampere, which is large enough to trigger an arcing short, and short circuit tests were conducted with a PVC‐insulated cable. Before an arcing short, a small amount of leakage current in the order of milliamperes was observed flowing through PVC insulation, which gradually increased and finally turned into an arc. On the other hand, no leakage current was observed before a physical short. These results indicate the following mechanism: When PVC insulation between conductors in a cable melts when a heat flux is applied, conductors often come close to and into contact with each other. In this case, the leakage current is unrecognizably small because the PVC insulation is not yet carbonized and still has a high resistivity. Meanwhile, when conductors do not come into contact with each other, PVC insulation is gradually carbonized and the leakage current increases until an arcing‐through‐char occurs. Copyright © 2016 John Wiley & Sons, Ltd.

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The dramatic increase in the number of radio stations in Germany over the past few years and the coincidental growth of competition have confronted German radio researchers with new challenges concerning contents and methodology. Increased competition has demanded a more precise measurement of the audience's needs and wishes. At the same time the growing complexity must be matched by a corresponding multivariate approach to data analysis. This study compares two methods of identification and delimitation of target audiences. The traditional approach utilizes sociodemographic characteristics—age, sex and education—to attain such a typology. This study proposes an alternative: an explorative segmentation of the audience using cluster analysis. The cluster analysis produces four types of listeners who are compared with regard to their listening behaviour, their loyalty to two popular Bavarian radio stations and sociodemographic attributes. The typology produced by this explorative approach appears to be superior for a sharp delimitation of specific target audiences. A series of path analyses is conducted to determine how perception of the quality of various aspects of radio programme content influences the evaluation of radio stations, and how these patterns vary among different listener types. The analyses show that quite diverse motivational structures seem to determine how different listener groups arrive at their evaluation of radio stations.