Predicting lead sheath cable failures

Assessing the condition of medium voltage cable and predicting cable performance is an ongoing effort at Con Edison. Some of our cables have been in use for nearly a century and, although the older cables have achieved a remarkable operating record, failure rates of transition joints continue to be a concern. Although Con Edison stopped installing paper insulated lead covered (PILC) cable in the mid-1980´s, it still accounts for 1/3rd of the 19,000 miles underground distribution network cable. Moisture infiltration from the environment is a common cause of insulation deterioration. The lead sheath is the first line of defense against moisture intrusion. In underground PILC cable, the lead sheath offer? undergoes rigorous wear from the rubbing against the duct material. Once damage has been sustained a path for the moisture is now established. What techniques are available to assess the damage sustained by in-service PILC cables? The Cable and Splice Center For Excellence at Con Edison has been exploring techniques that can be used in the field to assess the condition of the lead sheath. This paper presents the laboratory test data and a discussion of the field trial results