If a Transmission Line Hums in the Woods Can it be Heard?

The Northern Pass will make noise!

How loud will the noise be, exactly?

How often will the lines make noise?

At one of the Northern Pass hearings it was revealed that the high voltage transmission lines Hydro-Quebec and Eversource are proposing to construct through the heart of New Hampshire do make low level noise. And it says so here (although carefully worded): http://www.northernpass.us/assets/FNH_DIRECT_CURRENT_FINAL.pdf

And the noise increases on humid days, it was said at the hearing.

Does that also mean damp days, such as:

When it’s snowing?

When there’s fog?

When moist clouds blanket a town or village in the valleys? Which happens often in New Hampshire, especially in North Country.

Low clouds in historic Franconia village

When water vapor rises from rivers and lakes (often)?

During the common hoarfrost in the woodlands of North Country due to elevation variations.

Will all the above affect the noise level, aka corona, of the +/-320 kv DC/345 kv AC high voltage transmission lines being proposed?

Well, according to this web site, “Raindrops, snow, fog, hoarfrost, and condensation accumulated on the conductor surface are also sources of surface irregularities than can increase corona” (noise phenomenon associated with hv transmission lines under certain conditions), www.electricalnoise.wordpress.com – Abstracts, Notes on Various Electrical Engineering Topics (written so the average person like me can comprehend).

The title of my post isn’t completely accurate because the Northern Pass, +/-320 kv DC/345 kv AC high voltage transmission lines, won’t be humming just in the woods.

The transmission lines would also be humming near backyards, farm land, public parks, communities, businesses . . .

Here’s an example of humming high voltage transmission lines in Virginia:

In this video, the author says the transmission line is 500,000 volt or 500kv.

The Northern Pass transmission lines will carry 1090 megawatts, +/- 320 kv DC and 345 kv AC transmission. What is the decibel level of that?

Here’s another video of corona noise from transmission lines in Florida on a humid day (not sure of the voltage, however):

And yet one more, a power line at 400 kV (close to the power of Northern Pass?), for your listening pleasure:

Could the Northern Pass high voltage transmission lines get as loud as those lines on damp days?

Will the corona noise be as loud as the peepers in this wetland area off Sawyer Highway? I could listen to peepers all night, though!

The pleasant sound of peepers:


“Corona typically becomes a design concern for transmission lines at 345 kV and above but is less noticeable from lines like this 230-kV transmission line and the 34.5-kV collector lines, which will operate at lower voltages.

Corona also increases at higher elevations, where the atmosphere is less dense than at sea level. Audible noise will vary with elevation with the relationship of A/300, where A is the elevation of the line above sea level measured in meters (EPRI, 1985). Audible noise at 600 meters elevation will be twice the audible noise at 300 meters, all other things being equal. The 230-kV transmission line and the 34.5-kV collector lines were modeled with an elevation of 3,000 feet.

Raindrops, snow, fog, hoarfrost, and condensation accumulated on the conductor surface are also sources of surface irregularities that can increase corona. During fair weather, the number of these condensed water droplets or ice crystals is usually small and the corona effect is also small. However, during foul weather (e.g., wet or fog), the number of these sources increases (such as when raindrops stand on the conductor) and corona effects are therefore greater. During foul weather conditions, the conductor may produce the greatest amount of corona noise. During a heavy rain, the noise generated by the falling raindrops hitting the ground typically will be greater than the noise generated by corona and thus will mask the audible noise from power lines.”    https://www.oregon.gov/energy/Siting/docs/BrCW/ASC/AA.pdf pg. AA-15.


These quoted paragraphs are from another proposed transmission line project, one of many transmission line projects with reasonable information.

Interestingly, I couldn’t find anything about corona effect in Northern Pass documents or advanced internet searches, except for the link I shared in the first paragraph above. But maybe I had a bad research day. The information could be out there (somewhere within 20,000 plus pages of the filed documents).

What does this mean for the communities of New Hampshire, especially the mountainous communities in North Country?

And how do wildlife react to the visual effects of transmission lines? Well, take a look here: https://www.theguardian.com/environment/2014/mar/12/animals-powerlines-sky-wildlife

Please say NO to Northern Pass

The energy does not benefit New Hampshire

Northern Pass is NOT New Hampshire

Trees NEVER towers 

Sounds of nature NOT corona noise

A special place in Pemi Wilderness I photographed during a hike much like areas in North Country that will impacted by the Northern Pass high voltage hydropower transmission line

Please send an email to the New Hampshire Site Evaluation Committee, SEC, and say no northern pass through the heart of New Hampshire:










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