REG NASA-LLIS-0552-1997 Lessons Learned Potential Electrical Shock Hazard Involving Light Poles on Streets and in Parking Lots.pdf

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1、Lessons Learned Entry: 0552Lesson Info:a71 Lesson Number: 0552a71 Lesson Date: 1997-05-21a71 Submitting Organization: JSCa71 Submitted by: L. UnderwoodSubject: Potential Electrical Shock Hazard Involving Light Poles on Streets and in Parking Lots Description of Driving Event: Several randomly sample

2、d 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

3、 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

4、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 le

5、thal if the pole becomes energized. However, the shock hazard can be precluded by the installation of an upgraded supplemental ground to the earth.Lesson(s) Learned: Supplementary electrical grounding protection for streetlamp structures must be periodically verified.Recommendation(s): All personnel

6、 should understand the electrical shock hazard presented by an energized light pole. Therefore, do not touch street or parking lot light poles!Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Immediate interim measures are being implemented, as follow

7、s:1. new ground rods are being installed on each light pole on-site,2. a temporary means of insulating the base of each pole is being examined3. a preliminary report has been requested that will make recommendations for permanent repair or replacement of the existing exterior lighting system.Evidenc

8、e of Recurrence Control Effectiveness: N/ADocuments Related to Lesson: N/AMission Directorate(s): N/AAdditional Key Phrase(s): N/AAdditional Info: Approval Info: a71 Approval Date: 1997-05-22a71 Approval Name: Ronald A. Montaguea71 Approval Organization: NA3a71 Approval Phone Number: 281-483-8576Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-