Line clearance question.

[pdqdl]

like I stated from the beging your service drop is 110. now if you want to show me how much you really know what would the voltage be at the meter if your service loop was 385 feet and you were using 6 gauge copper wire. assuming the voltage was 115volts at the tap.

The best electrician in the world cannot answer that question. Here is why:

Voltage across a conductor changes according to the amperage traveling down the wire. If you hooked up the 385' wire to the pole (115v) and put a voltmeter across the terminals, you would get 115 volts (using your numbers) at the end of the wire just like you do at the pole.

Now hook up a 200 amp service to that wire, and run a stove, a 5 hp air compressor, a welder, and all the lights in the building. The electric current traveling down the wire has gone from nothing to 200 amps. Measured voltage at the meter will go down according to the resistance of the wire AND the current traveling on the wire.

Knowing only the length and gauge of the wire is not enough.


BTW: in other posts you keep referring to 110v on a common line drop. Many years ago, I think household current was commonly 110 volts. I'm pretty sure that it is almost standardized at 120v in the USA.

There are TWO hot wires coming into the house, each carrying 120v. Since this is AC (alternating current), each of the wires is carrying 120v to ground. HOWEVER! You need to understand that each of the two hot wires has an opposite polarity from the other. The voltage in an opposite direction, so one wire is pushing voltage (-) while the other is pulling (+), so the two voltages add up to 240v. Then they reverse polarity, and the current changes direction. 60 times per second!

In your house, most appliances are hooked up to just one hot wire and the neutral, so you only get 120v. The stove, the air conditioning unit, and other bigger appliances need more electricity, so they get it by connecting to both hot wires and running on the 240 volts between the two hot wires.

You can see this best on your stove: it is wired 240, but the oven light and the clock run on just 120 volts. These little devices don't need much electricity, so they are only attached to one leg of the electric service to the stove. If you detach the neutral, the stove will still heat up, but the light bulb and clock won't come on. (probably not true for modern electronically controlled stoves)

 

[kharman]

Up here in Colorado I work for a line clearing company. Our standards are, there must be no less than 5 feet off center. Meaning a total of 10 feet clearance. 5 on eather side of the line. Ground to sky. Nothing under the line and nothing above the line. Storms can play havic on the lines and when thay get to swinging in the wind along with the trees things can get zapped and then you have some real issues. This to dependes on the line voltage that is going up. Most of the lines that run a house is below .725 kv - and 15 kv. the triplex that runes to the house from the meter pole is around a 220v. this line require a total clearance of 18 inches. Hope this helps just remember that this could vary from state to state.

Trailduster: If you don't mind sharing, what line clearance company do you work for? I am doing a research report on vegetation management and am looking for company names nationwide.

 

[ropensaddle]

Amps do the killing.
Volts are what pushes the amps through your bod.
Ohms is what protects you from the volts & amps.

Sooo...I gotta disagree rope. Ohms is NOT what kills, it's not having enough of them that will kill you, given some exposure to the volts and the amps.

A little high school physics: V=IR
where V is volts, I is the amperage, and R is ohms resistance. When Voltage is very high, in order to keep the electrocuting current very low, you need almost infinite resistance.

(more on that in the next post)

Ok lol I just seen this I said ohms or lack of somewhere in this topic.A clean dry insulated pruner is infinite ohms and has saved my skin in several occasions. The whole point I am making about ohms is; unless its high enough potential to jump like 500 kv, ohms determine the contact. So if you do not contact the source or if contact is infinite ohms, your not killed or even energized. It don't matter about any other factor in normal distribution. In transmission it will jump out and contact you! It will on distribution if your breaking minimum separation rules but the distance is considerably less.

Staying out of the path of least resistance has also saved my Hyde removing burning overhang. Ohms or lack of determine fatal contact because if you have enough space or make contact with infinite resistance (measured in ohms) it don't matter if its a million volts and 300k amps you did not touch or get close enough to be touched