scope:

Description of Driving Event:

Several randomly sampled exterior street and parking lot light poles were found to have defective electrical grounds that could result in a potentially lethal electric shock hazard if the pole is touched by a person.

The hazard is primarily a result of two conditions:

1. The original design of the power distribution circuit lacked an equipment grounding conductor even though the installation met the National Electric Code at the time.

2. The normal breakdown over time of the materials utilized in the supplemental ground rod which was installed to correct the original design deficiency.

The poles are energized primarily at night, but can be remotely energized for testing and repair during daylight hours. Certain power distribution system failure modes may result in an energized light pole. While it is unlikely to have a combination of a defective grounding condition and a power system fault, the condition can be lethal if the pole becomes energized. However, the shock hazard can be precluded by the installation of an upgraded supplemental ground to the earth.