How do they fix Power Lines?

[coopns]

Might be the dummy question of the day...

After some recent storms here in MA, tons of wires down. Gets me thinking, so how do they repair a power line that is down? Like they wouldn't splice a line would they? Like say they had to cut a down line, how (not to technical) would they repair that?

 

[Tempest]

Wirenuts...LOL

 

[NHGUY]

Electrical tape! lol UL approved of course.

 

[electrolover]

They first run a the line directly to ground so they can work on it a little safer and then splice in the new line. After its done they remove the ground rods and conductors and its all good.
Im not a lineman, but I am an electrician and I see it done once. It was a point of interest for me so I payed close attention. What I found out is you cant pay me enough to be a lineman

 

[spackard]

Kind of think it's an assembly line.
First, fix poles.
Next, string lines on poles.
Third, apply power.
Fourth, place call to telco so they can string/repair their lines.

 

[Shannow]

1st year out from University, spent a couple of weeks going out with the linesmen doing just that.

When they are down but not broken, stand a new pole, and use a crane to get the wires back up (steel core, Al outside).

When they are broken, they put a new part in, then have a hydraulic crimping sleeve that joins the two loose ends.

As it's a shear type connection Al/Al, they don't like putting them over roads etc. as they are a weak point (but necessary)

 

[SuperDave456]

I've spoken to a few linemen. I met them when I was on vacation and we got to talking about electrical issues.

They would talk about working on the Gulf Coaster after a Hurricane. Both of them had been up on a pole when the guide wire was cut, and the guide wire was the only thing keeping the pole standing, the base had rotted out.
One broke a leg, the other landed on soft ground and walked away.

Of course this is 15 years ago. Not sure if they still Climb poles, or if they can bail out of their climbing gear like they used to.

Around 2004, when I was in Waco, a lineman didn't follow procedure and was killed about 30 feet from my Apt. I didn't have power and I went to ask the Police blocking the street what was going on.

Lots of danger working on several hundred volts of electricity 30 feet off the ground.

 

[electrolover]

Several thousand volts is more like it. Its usually 4800 volts phase to phase in residential and up to 25000 industrial.

 

[crw]

I wonder why more lines aren't buried? When I was growing up in the Seattle suburbs (1970's) all of my neighborhood had no overhead lines where the weather could impact them. But where I live today, in Idaho, overhead lines are still all over.

 

[xxch4osxx]

Originally Posted By: crw
I wonder why more lines aren't buried? When I was growing up in the Seattle suburbs (1970's) all of my neighborhood had no overhead lines where the weather could impact them. But where I live today, in Idaho, overhead lines are still all over.
I think cost has alot to do with it. It costs alot more to bury them plus when repairs are needed, they have to dig them up again, also increasing costs. When they are out in the open, it is much easier to spot problems and work on them right away.

 

[Warstud]

 

[Mr Nice]

Even 480 volts is deadly. I know a guy working on a CT imaging equipment that almost got killed.

 

[exranger06]

Originally Posted By: xxch4osxx
Originally Posted By: crw
I wonder why more lines aren't buried? When I was growing up in the Seattle suburbs (1970's) all of my neighborhood had no overhead lines where the weather could impact them. But where I live today, in Idaho, overhead lines are still all over.
I think cost has alot to do with it. It costs alot more to bury them plus when repairs are needed, they have to dig them up again, also increasing costs. When they are out in the open, it is much easier to spot problems and work on them right away.

There's usually no digging involved in replacing cable. Most underground cables are in conduit. Workers can access the cable at a transformer, splice box, or other equipment and pull the cable through the conduit. Some old cable is direct buried, but it's becoming less common. Underground systems are a lot more expensive to install, and they're harder to diagnose when something goes wrong, since you can't readily see failed components as you would on an overhead system. And things DO go wrong, they're not the pinnacle of reliability everyone loves to think they are. Transformers melt down, cable insulation breaks down, there's water intrusion, etc etc. I'm not a lineman, but I am an engineer for an electric utility.

 

[exranger06]

Originally Posted By: electrolover
Several thousand volts is more like it. Its usually 4800 volts phase to phase in residential and up to 25000 industrial.

My utility is mostly 13,800 V line-to-line (7980 V line-to-ground). That's for the entire system, residential and industrial. There's still some old 4160 V and some 2400 V on the system (less than 5 percent), and that will eventually be replaced with 13.8.

 

[GMFan]

Like a BOSS:



The highest I've worked in proximity to was a 33kV substation voltage but transmission voltages can go 500kV+

 

[Nick R]

Originally Posted By: crw
I wonder why more lines aren't buried? When I was growing up in the Seattle suburbs (1970's) all of my neighborhood had no overhead lines where the weather could impact them. But where I live today, in Idaho, overhead lines are still all over.
W

Working for a major Cable provider, I can assure you that it's because of cost. If someone who lives past where the line ends wants service, and it wouldn't be covered under the normal installation cost, it would cost a heck of a lot less if the lines are run on a pole, than if they were underground. They would also be more likely to be able to get it without having to pay the construction cost.

 

[GMFan]

The lines on the residential poles are typically 13.2kV, 13.8kV or 12.47kV depending on where you live in the country and then the little bucket transformers send it your way at 240/120V.

I'm not a linesman, but I imagine before working on lines they open the fuse cut-outs mounted on the poles with hot-stick to de-energize the lines or open the substation breaker if things are really mangled. Downed lines can remain energized in a storm because the relays at the substations see the short circuits as loads and don't detect the line is down or the line is down but not shorted until someone contacts it.

I've seen utilities use bare non-insulated wire on the poles at residential voltage. Linesman have high rated voltage gloves to handle them. Even if insulated never trust touching it because I've seen plenty of wire where the insulation has melted off due to high loads during summer. Utilities like to abuse their cable.

 

[rslifkin]

Originally Posted By: LT4 Vette
Even 480 volts is deadly. I know a guy working on a CT imaging equipment that almost got killed.


480 is right around the range where it's most deadly. Plenty of voltage to push lethal amounts of amperage through a not-very-conductive human, but not enough to shock you hard enough to push you backwards, so you're likely to get stuck to it and just fry.

 

[exranger06]

Originally Posted By: GMFan
The lines on the residential poles are typically 13.2kV, 13.8kV or 12.47kV depending on where you live in the country and then the little bucket transformers send it your way at 240/120V.

I'm not a linesman, but I imagine before working on lines they open the fuse cut-outs mounted on the poles with hot-stick to de-energize the lines or open the substation breaker if things are really mangled. Downed lines can remain energized in a storm because the relays at the substations see the short circuits as loads and don't detect the line is down or the line is down but not shorted until someone contacts it.

I've seen utilities use bare non-insulated wire on the poles at residential voltage. Linesman have high rated voltage gloves to handle them. Even if insulated never trust touching it because I've seen plenty of wire where the insulation has melted off due to high loads during summer. Utilities like to abuse their cable.

A lot of overhead primary isn't insulated at all, even when it's new. Bare copper and aluminum is extremely common, as well as "tree wire," which has a thin rubber coating to protect against rubbing trees, but is not enough to insulate from human contact. Downed lines can also be energized from people backfeeding generators.

 

[csx7006]

Just out of cuiosity. I have a S&C cutout that I brought off feebay. Is there a way I can put one of these for my shed?What size fuses can I get?