Project: 193700 #3726
 

This project is to review safety issues and practices to mitigate step and touch voltages on buried metal objects located near substations.

Scope of Study

This project is to include a literature review to identify safety concerns applicable to buried metal objects located near electrical substations. Included in this might be sign posts, street lights and non-utility fences. The review is to include standards and guidelines along with utility practices and mitigation alternatives to ensure that safety limits are achieved. Particularly, long metal objects that extend well away from substations are of concern. Included in this are metallic water or natural gas pipes as well as railroad tracks.

Some additional considerations related to fencing include:

  • The substation fence may be near the propertly line, and it may or may not include a buried perimeter grounding conductor outside the fence.
  • What consideration should be given for conductors falling on a fence?
  • Metallic fences are often located on transmission line right-of-ways. Additionally, some fences may be an electric fence.

This project is to include:

  • Identifying metal objects near a substation which might create a step/touch voltage safety concern
  • Defining step/touch voltage limits allowable on adjacent metal objects
  • Test methods to measure step/touch voltages to determine if a safety issue is present
  • Methods and material to mitigate step/touch voltages on adjacent metal objects. Illustrations would be very helpful.
  • Long-term monitoring to ensure step/touch voltages are maintained within safe allowable limits