Non qualified personnel working around LV (<480V) power lines

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shawndburg

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A question was brought to me by crane operators and welders the other day. How do they deal with working around overhead low voltage powerlines? We cover our MV power lines, and they know to stay 10' away from them also. But I didnt know what to tell them about how to handle the fiberoptic lines and other stuff below that is below 480V. Any suggestions? Am I overlooking it somewhere in the code?
 
I think you need to put up some kind of barriers to keep people that do not belong there out of areas where there is a hazard. That is generally what OSHA requires.

On a temporary basis, caution tape is probably adequate.
 
What voltage is low enough not to worry?

What voltage is low enough not to worry?

That seems to come up in safety meetings. the answer is all of them, networking cables and phonelines the whole 9 yards.
Typically when we are clean and dry you would not even get a tingle from brushing against a low voltage circuit like 24 VDC, but if you break down the resistance of the skin like a sweaty construction worker even low voltages can be enough to conduct. I am not going to get into the physiology of the human heart and how little current it takes to cause problems, but you can see my point. Even low voltage could be a problem.

There should always be a site plan especially if a crane is involved.
 
shawndburg said:
A question was brought to me by crane operators and welders the other day. How do they deal with working around overhead low voltage powerlines? We cover our MV power lines, and they know to stay 10' away from them also. But I didnt know what to tell them about how to handle the fiberoptic lines and other stuff below that is below 480V. Any suggestions? Am I overlooking it somewhere in the code?
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Fiberoptic carries light not current. Communication cables such as Ethernet (not Ethernet with Power) carry minimal voltages where you're more likely to destroy the cable or entangle yourself. Actual power carrying conductors including 24V DC through 480V AC should be protected from accidental damage not strung across open areas. The boxes, conduits, enclosures, raceways should be all that's required to keep them out except for excessive force or stupidity. If they have to work near exposed buss or unprotected conductors then they need to be qualified.
 
Running insulated 480V and fiber cable strung on a messenger is a common practice in large petro / chemical plant. At our plant we have the highest voltage insulated conductiors (15KV) at the top, two feet under we run the 480V and two feet below that we run fiber and comm cables. The problem for most unqulaified folks they can not tell what in in the cable. The question becomes when working near (a crane lift) what cables if any need to be guarded?

We install orange sleeves on the 15KV & 480V cables when non qualified folks are working in area. Note putting on the sleeve exposes our electrical folks to hazards while installing the additional protection. The sleeve will provide addition insulation and prevent damage from minor contact but if a crane lift goes wrong ... no need to go into the details.

I know in a perfect world we would shut off the power, we try our best to plan work around production outages but things break and often shutting down the power would pose a greater safety hazard.
 
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