How many volts, safe distance from power lines?


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Old 08-23-22, 09:52 PM
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How many volts, safe distance from power lines?

I live at the end of a cul-de-sac. My house and my neighbor's house are the last homes that are fed by the city power lines. I have some trees that are growing near these lines. I was wondering how close tree trimmers can get to these lines. My Internet research suggests that these lines are low voltage (somewhere between 120 and 600 volts).
In this picture, you can see the last pole where two insulated wires wrapped around a bare metal wire come in, and two insulated wires go out on another bare metal wire (eventually to my house).
 
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Old 08-24-22, 01:34 AM
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Power companies usually take care of trimming branches that encroach on their right of way, often hiring contractors that specialize in power line work. Trimming helps reduce those expen$ive night-time/weekend "power out" calls. Tree trimmers were in my neighborhood just a few weeks ago.

Since you are on a dead-end line, call your power company and ask them to evaluate any encroachment. Trimming around the span from the last pole to the home, may be the responsibility of the homeowner.

OBTW: Voltage on the line you described is almost certainly 240 volts between the two insulated conductors and 120 volts between each insulated conductor and the bare support cable.
 
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Old 08-24-22, 01:38 AM
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I called the city once and they said that my trees were fine. My reasons to trim the tree are aesthetic. I'm just curious how close these tree trimmer guys can get to these lines when they're up in the trees, assuming you are right about the voltage. 3 feet?
 
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Old 08-24-22, 06:40 AM
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Those are 240V low voltage lines, It is generally safe to work near it, but you must take care not to damage the line. It will be safe as long as insulation is not damaged and you don't hit it hard with something (heavy machinery, tree branch, ladder, etc)

Power companies usually don't cut tree around low voltage lines unless the branch is actually touching it.
 
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Old 08-24-22, 08:59 AM
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Do not call "the city". They are not responsible for tree maintenance around power lines. That is your power companies responsibility.
 
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Old 08-24-22, 11:32 AM
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Tree trimming between the pole and the house is typically the homeowners responsibility.
That doesn't mean that the homeowner should do it themselves.

Tree trimming companies are aware of the dangers and use insulated tools as well as personal insulation.
 
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Old 08-26-22, 03:17 PM
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And what about just the line that comes right up and connects to one's house... Assuming that's 120 volts, how close can an electric chainsaw get to that line without some electricity arcing? And how close can a battery-operated trimmer get to that line?
 
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Old 08-26-22, 06:23 PM
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And what about just the line that comes right up and connects to one's house... Assuming that's 120 volts, how close can an electric chainsaw get to that line without some electricity arcing? And how close can a battery-operated trimmer get to that line?
Feeds to the house is exact same voltage as those low voltage lines. 240V split phase. You get 120V by connecting one of 240V line and neutral.
With this voltage, you will not get any arcing unless you actually cut into the conductor and complete circuit to ground or another pole. You can even touch it with bare hand and not get shocked (as long as insulation is good). Think of it as exactly same thing as extension cord except it is capable of higher current and not fused (meaning if you get short, it will arc until wire melts or transformer blow up)
 
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Old 08-26-22, 06:39 PM
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Those wires are insulated except for the grounded conductor. (Neutral) As long as you do not come in physical contact with the wires you will be fine.
 
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Old 08-27-22, 09:13 AM
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Those wires are insulated
Those wires are usually insulated. Older wires can have the insulation degraded. I would always keep a healthy distance from the service entry wires.

As others have said, they are low enough voltage that they won't arc, but the upstream fuses are rather large (1,000A), so I wouldn't want to accidentally come in contact with one.
That's why power companies recommend you keep 10' distance between you and power lines. Even if the ladder or your tree trimmer slips, you're not at risk for touching them.

Lastly, it's probably not needed in your situation, but power companies will come out and install temporary protectors over the wires if you or contractors do need to work near them.
 
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Old 08-27-22, 02:02 PM
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So, what you're saying is that this 10-foot recommendation was made under the assumption that some idiots might fall from a metal ladder into an unshielded line -- not because electricity could arc 10 feet over to the ladder?

Separate question: Yes, I know that this does not apply to low voltage lines. But, I'm curious, with high voltage, if there was potential for arcing, would that electricity be more attracted to an electric power tool or a battery-operated power tool?
 
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Old 08-27-22, 02:14 PM
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So, what you're saying is that this 10-foot recommendation was made under the assumption that some idiots might fall from a metal ladder into an unshielded line -- not because electricity could arc 10 feet over to the ladder?
Correct.

​​​​​​​But, I'm curious, with high voltage, if there was potential for arcing, would that electricity be more attracted to an electric power tool or a battery-operated power tool?
Neither. It would depend on the tool being used and if there is a path to ground. For instance, if you were using a metal saw standing on an aluminum ladder that is in direct contact with the earth there is a much higher chance of an arc than if you were using a plastic power saw standing on a fiberglass ladder.
 
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Old 08-27-22, 03:01 PM
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I was thinking of the battery inside the tool. So, I guess AC current is not attracted to a DC-charged battery.
 
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Old 08-27-22, 04:58 PM
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Those wires are usually insulated
It is always insulated. Degraded insulation should be taken care of immediately by the power company.
There may be degraded uninsulated wires on the pole, but never on wires feeding to a house. Also, the op has triplex, so if insulation failed on that, very dangerous situation can occur.

I was thinking of the battery inside the tool. So, I guess AC current is not attracted to a DC-charged battery.
Battery inside tool is on its own circuit and will not attract AC in anyway.
 
 

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