Impulse strength of cable insulation

INSULATED CABLES often are exposed to lightning and often have been damaged by lightning, especially rubber- or cambric-insulated cables of medium or lower voltage. It is also true that some service trouble has been improperly attributed to lightning. Knowledge of the impulse strength of cable insulation is necessary to analyze such cases correctly and to minimize lightning trouble by proper cable design. In spite of the practical need for such information there seems to be a conspicuous lack of it in the literature.