overhead power lines and ground conductor

[PG1995]

Hi

Please have a look here. I understand that ground conductor (in yellow highlight) is there to protect phase conductors from direct lightning strike. But I have noticed that sometimes brown/red spherical ball-type structures are also mounted on that ground conductors at fixed intervals over a certain length. Previously, I had thought that they use these ball-like structures where an airport is located nearby but recently I have found that these structures were used in an area which had no airport in its vicinity. Could you please guide me with it?

Regards
PG

Reference:
1: https://en.wikipedia.org/wiki/Overhead_power_line

 

[nsaspook]

Might be for crop-dusters flying nearby.

 

[PG1995]

Thank you.

But I highly doubt it.

 

[JimB]

Only a thought, but I have the idea that the "balls" may be to make the lines visible to large birds. By large I mean something the size of a goose or a swan.

On a slightly related topic, in the UK all pylons have a natural galvanised steel colour.
In some countries it is customary to paint pylons and radio towers in contrasting red and white bands.
One that sticks in my mind is France. On the approach to Paris CDG, one passes over numerous pylons painted red/white several hundred feet below the aircraft.
The random thought occured to me, "If the pilot of a Boeing/Airbus/Whatever is so low on the approach that the pylons need to be highlighted to aid avoiding them, he is MUCH BIGGER TROUBLE and probably could not avoid the pylon if he wanted to".

JimB

 

[jpanhalt]

Same answer different source: https://www.straightdope.com/columns/read/773/why-are-those-red-balloon-things-on-overhead-wires

They are quite common in the US: https://i.imgur.com/yVUlK.jpg

John

 

[Nigel Goodwin]

On a slightly related topic, in the UK all pylons have a natural galvanised steel colour.

They do paint them though, there are pylons in the field at the back of me - and they painted them a number of years ago - the undercoat was 'coloured' (can't remember what colour now), but the final finish was a natural steel kind of colour just as pylons always look.

 

[MikeMl]

These are usually placed where fixed-wing and helicopters are likely to operate. I have two at the end of my private runway where a 40kV power line crosses to make the line visible. I get to "land over a 50ft obstacle" every time we have winds from the east. Ours is not a public use runway, so the balls are there only because the power company is aware of our low-use runway.

I also see these out in the country where there is no runway, but there is a natural gas or oil pipeline crossing under a power line. The pipeline companies use fixed-wing or helicopters to periodically patrol their pipeline rights-of-way. The balls are placed directly above where the pipeline is buried.

For those that missed John's link:

 

[Ian Rogers]

I was involved with ESCOM in South Africa and we used to help with the construction of pylons.... I was only there for a year, and have never seen red ballons... We sometimes fitted dampers to stop the cable oscillating... But these were usually two red metal bars suspended from the cables.... I was only 16 so I really didn't too involved...

 

[AnalogKid]

Thank you. But I highly doubt it.

Believe it. Very common in the Colorado Rockies, and has nothing to do with birds. De Plane De Plane

There is no one universal standard, but most of the high voltage transmission lines in the US are three-phase-delta. This system has no ground as part of the transmission circuit. The wires at the top of the towers are the datacom network for the power grid.

ak

 

[MikeMl]

...The wires at the top of the towers are the datacom network for the power grid.

ak

Not where I live. The top wire is there to catch the lightning bolts...

 

[ronsimpson]

The wires at the top of the towers are the datacom network for the power grid.

It has been years so things might have changed but data is sent down the power wires as RF.
The top wire here is connected to ground at almost every pole.

 

[kubeek]

You could easily have an optical fibre strung along with the ground conductor, so in modern installations it might serve multiple purposes. Actually power lines seem like a nice and easy way to get the fibers almost anywhere without digging new trenches.

 

[nsaspook]

Not where I live. The top wire is there to catch the lightning bolts...

and crazy pilots.

 

[MikeMl]

and crazy pilots.

Common with cropdusters. Besides, he wouldn't hit the ground wire, which is on top.

Look at it this way. You are totally comfortable driving your car at 70+mph within inches of an oncoming car or a bridge railing. You get used to doing it without thinking about it...

Your car doesn't know how close you are to that obstacle. Neither does an airplane. Only the pilot knows...

 

[jpanhalt]

I couldn't make out the outline of the rudder and fin well enough to be sure, but that airplane could be a Piper PA-25 (Pawnee). Some of them were equipped with wire cutters in front of the windshield. It is a fairly flat windshield, and a wire will pretty much slice the top of the cabin off. The purpose of the cutter/diverter was to force the wire over the cabin. I am not sure this is one, but it looks similar to one I have seen:

John

 

[ronsimpson]

and crazy pilots.

Here; There is a yellow plain that crop dusts just like that.

 

[JimB]

Further to the topic of balls on power lines...

On page 85 of this document:
https://www.aplic.org/uploads/files/11218/Reducing_Avian_Collisions_2012watermarkLR.pdf
there is this:

AERIAL MARKER SPHERES
(AVIATION BALLS)
Aerial marker spheres (or aviation balls) were
one of the earliest devices used in an attempt
to reduce bird collisions (Figure 6.8 and Figure
6.9). Originally they were used to warn
aircraft pilots of power lines. These large,
colored balls are usually attached to distribution
phase conductors or transmission shield
wires. They are available in a variety of diameters:
23 cm (9 in) to 137 cm (54 in). The
most often used sizes for line marking are
23 cm (9 in) and 30.5 cm (12 in).
Aerial marker spheres are available in a
variety of colors, including international
orange, gloss white, or gloss yellow.

So although the balls were originally intended to prevent aircraft collisions, they have also been used with a modicum of success to prevent bird collisions.

As someone who has an interest in birds (no, I am not a twitcher, far from it!) I found the document quite interesting from an electrical and ornithological point of view.

JimB