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Grounding Around 500kv transmission fence lines #147489
10/26/02 09:05 AM
10/26/02 09:05 AM
R
Rillor  Offline OP
Junior Member
Joined: Oct 2002
Posts: 1
Allentown, PA
I have a safety issue that maybe someone can provide me a better explanation and/or point me in the direction to where I can find the correct information.

We are to begin working next to a fence line around a 500kv distribution line. The distance to the switches is well above the minimum clearance established by OSHA and we are grounding all equipment/material to the grounding cable (located on the fence that goes to the underground grid) for an added safety measure. We are told to keep a minimum distance of 10' away from the fence in case there is failure in the distribution system (lightning strike, switch failure, etc.) and the potential of the underground grounding grid to be energized and prevent any pipe within 5-10 feet of the fence to act as a conductor.

My questions:
1. If we are grounding to the fence cable and there is a failure to the system, can the electric current go up our grounding cable and cause a shock potential to the equipment / material it is in contact?

2. To dissipate any static potential we are grounding all material before being touched. Should a separate grounding source be used or is it best to attach to the ground on the fence. And, if we do, will the potential in Question #1 come into effect.

3. The grounding grid extends 5' outside the fence, as indicated by the colored stone. Is a 10' clearance from the fence an adequate distance to prevent the pipe from acting as a conductor in case of a failure, as well as, minimize any static charge?

I would appreciate any assistance (answers, information, resource direction) in this matter. Thank you for your assistance. I can be reached at my email address below.

Rillor

Safety Coordinator
sparker@fast.net

Arc Flash PPE Clothing, LOTO & Insulated Tools
Re: Grounding Around 500kv transmission fence lines #147490
10/26/02 11:43 AM
10/26/02 11:43 AM
B
Bjarney  Offline
Moderator
Joined: Apr 2002
Posts: 2,527
West-Southern Inner-Northeast ...
The quoted 10-foot dimension is likely an inadequate distance for the job at hand where workers are not outfitted with appropriate, rated PPE and formally trained in aspects of OSHA "minimum appraoch distance." The spacing given looks too close for that of persons working near an energized and grounded 230kV line.

Some very condensed, applicable text may be: http://www2.transmission.bpa.gov/About_TBL/Publications/PDFs/livingWorking.pdf http://www.esci.net/SafetyFiremanArchiv.html http://www.ameslab.gov/esha/Lessons_Learned/Yellow_Alerts/000211a.htm

29 CFR 1910.269 and 1910.333 are very serious business.

It is strongly recommended contacting the line owner and notifying them of your intentions; requesting clearance to do the described tasks. Use of conductive materials in areas near energized lines has most serious safety, legal {and ultimately financial} implications.


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