Prevention of potential hazards in underground system maintenance

In early 2001 the Safety Committee of San Diego Gas and Electric (SDG&E) began a review of their work practices used for underground maintenance. Substantial information related to worker safety had been developed. The use of equipotential zones was now widely accepted and their use was now included in CFR 1910.269 as the recommended protection method for working on de-energized conductors. The committee´s goal was to evaluate the current SDG&E practices versus the latest information and determine the effectiveness of their work practices in light of all these changes. What they found was that only a small amount of actual test data was available for underground distribution work. They felt that it would be necessary for them to develop a test program to adequately evaluate their underground distribution (URD) methods. Electrical Safety Consultants International was invited to work with SDG&E to develop the program. The results of this test series documents new information and is of interest to all utilities that use underground distribution and are concerned about the safety of their workers. This article describes the test details, and results for workers standing in or outside of vaults with varying degrees of protection.