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Digging under High Tension Electric Lines 4
- Thread starter TBCEng07
- Start date
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- #2
I'm not sure how far excavating equipment needs to be but we have had projects where the power company required a minimum of 30 feet vertical clearance from finished grade to the lowest sag point in the power lines. In fact we have been required to survey the horizontal and vertical positions of the power lines for verification. The power companies have factors they apply to the sag for very hot days when the sag is at its most extreme. Unfortunately, that is also during construction season.
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- #3
I don't know the answer to this, in your locale, but I read the following in at least a local “FACE” ( etc.) discussion of an incident, it appeared specifically involving an excavator and an overhead power line several years ago:
“Discussion: OSHA regulation 29 CFR 1926.600(a)(6) requires that boomed earth-moving vehicles comply with the requirements of 29 CFR 1926.550(a)(15) when working or being moved in the vicinity of power lines. This standard specifies that the minimum clearance between electric lines rated 50kV or below and any part of the boomed vehicle shall be 10 feet, unless the electrical lines have been "deenergized and visibly grounded" at the point of work. A 10-foot clearance would ensure that the vehicle would not contact and cut the overhead line, as in this incident, or become energized because of the contact. When a 10-foot clearance is difficult to maintain by visual means, a designated person can observe clearance between the lines and the equipment and give timely warning of imminent contact to the operator, or the local utility company should be contacted to deenergize the power line before work starts.”
While I could see some argument that this might be quite difficult to maintain in some situations; there is certainly no doubt one needs to maintain some reasonably safe distance and particularly from highly energized lines! (and I think the above contains at least some generally good thoughts/suggestions in this regard)
“Discussion: OSHA regulation 29 CFR 1926.600(a)(6) requires that boomed earth-moving vehicles comply with the requirements of 29 CFR 1926.550(a)(15) when working or being moved in the vicinity of power lines. This standard specifies that the minimum clearance between electric lines rated 50kV or below and any part of the boomed vehicle shall be 10 feet, unless the electrical lines have been "deenergized and visibly grounded" at the point of work. A 10-foot clearance would ensure that the vehicle would not contact and cut the overhead line, as in this incident, or become energized because of the contact. When a 10-foot clearance is difficult to maintain by visual means, a designated person can observe clearance between the lines and the equipment and give timely warning of imminent contact to the operator, or the local utility company should be contacted to deenergize the power line before work starts.”
While I could see some argument that this might be quite difficult to maintain in some situations; there is certainly no doubt one needs to maintain some reasonably safe distance and particularly from highly energized lines! (and I think the above contains at least some generally good thoughts/suggestions in this regard)
- Thread starter
- #5
A 10-foot separation is a good rule of thumb to start, but certainly coordinate with the utility that owns the lines - they will likely have the final say. I have seen drawings where the computed "hot weather sag" has been shown on the drawings for that particular transmission line. I have also seen a buffer actually hung from active lines that were going to have significant long-term activity underneath. The buffer appeared to be a string of insulators with flagging at the lower end.
msquared48
Structural
Seriously, the power company managing the line would be your best bet. I used to work for one many years ago. OK...many, many...
The distance can also vary with the weather conditions too, specifically the humidity.
Mike McCann
McCann Engineering
The distance can also vary with the weather conditions too, specifically the humidity.
Mike McCann
McCann Engineering
as an absolute minimum, for normal lines (side of the road wooden post kind of lines) i stay at least 10'+. for high tension lines, i stay at least 30'+ away from them and the base of the structure. i will usually opt to not dig under and/or around them at all and i won't put my drillers under them. to be honest, i don't even like walking next to a machine that is simply passing under high tension lines. i may be a chicken, but at least i'm not a fried chicken. moreover, if you've never had a coworker and/or good friend killed because of lack of safety awareness (that could have easily been avoided with a little caution), then i suggest that you reconsider your choices so that you don't have to live with that kind of guilt. i can assure you that the guilt spreads whether you personally had input to the situation or not. i can't imagine the guilt if i'd actually attributed to my friend's death.
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- #10
Well this guy wasn't digging but I imagine the results would be similar.
Here are some clearance requirements from California. The amount of clearance is a function of the voltage being carried by the lines:
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- #12
There is an Ansi Guideline, see link ; it's about halfway down (after the case descriptions)
50 to 200K 15 feet.
50 to 200K 15 feet.
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