Grounding exterior acoustic wall in highways
- Thread starter sharan
- Start date
- Status
- Location
- Illinois
- Occupation
- retired electrician
Why would it need to be grounded or bonded?
- Location
- Wisconsin
- Occupation
- PE (Retired) - Power Systems
What would be the probable method in which these steel 'posts' would become energized?
How are these steel 'posts' connected to earth; concrete base with footings, pounded into the dirt for several feet, or something else?
- Location
- Lockport, IL
- Occupation
- Retired Electrical Engineer
Are there any lights mounted on the walls? Any power receptacles mounted within the walls? If there is no electrical equipment attached to the walls, then there are no requirements for grounding or bonding.
This is the main concern:
Our firm is in need of a certified letter from an electrical engineer licensed in the State of Illinois in regards to the potential safety issues of a concrete noise wall below high voltage power lines. It is our understanding that the lines that are 26? above the top of wall, with a 20? clear zone, have 345 kv and the lines that are 16? above the top of wall, with a 14? clear zone, have 138 kv.
Our firm is in need of a certified letter from an electrical engineer licensed in the State of Illinois in regards to the potential safety issues of a concrete noise wall below high voltage power lines. It is our understanding that the lines that are 26? above the top of wall, with a 20? clear zone, have 345 kv and the lines that are 16? above the top of wall, with a 14? clear zone, have 138 kv.
- Location
- Wisconsin
- Occupation
- PE (Retired) - Power Systems
Then you really should contact a properly registered engineer.
But again I ask, how are the steel posts 'attached' to the dirt? Most of the ones I have seen appear to be installed similar to the support columns of a building.
- Location
- Lockport, IL
- Occupation
- Retired Electrical Engineer
My Illinois PE license has expired, and I have no plans to renew it. So I can?t give you the letter you need. But I can say that,
(1) If a 345 line fell onto a person, that person would die,
(2) If a 345 line fell onto a concrete wall, the wall could become part of a current path that would bring fault current back to the source, and a person standing on or near the wall might get a fatal shock, and
(3) No amount of grounding or bonding would have any impact whatsoever on the nature of risk to any person standing on or near that wall.
Current does not seek a path to ground (i.e., to planet Earth). It seeks a path back to its source. So if you bond all steel support poles to each other, and run a bond wire back to the substation from which the 345 line originates, then that wire might help carry fault current back to the source. But given the total impracticality of such a plan, there is no remaining value in bonding the poles to each other, or in improving the connections between the poles and the nearby dirt.
As I am sure any engineer who works with transmission systems would tell you, if there is a downed power line, be somewhere else.
(1) If a 345 line fell onto a person, that person would die,
(2) If a 345 line fell onto a concrete wall, the wall could become part of a current path that would bring fault current back to the source, and a person standing on or near the wall might get a fatal shock, and
(3) No amount of grounding or bonding would have any impact whatsoever on the nature of risk to any person standing on or near that wall.
Current does not seek a path to ground (i.e., to planet Earth). It seeks a path back to its source. So if you bond all steel support poles to each other, and run a bond wire back to the substation from which the 345 line originates, then that wire might help carry fault current back to the source. But given the total impracticality of such a plan, there is no remaining value in bonding the poles to each other, or in improving the connections between the poles and the nearby dirt.
As I am sure any engineer who works with transmission systems would tell you, if there is a downed power line, be somewhere else.
- Location
- Wisconsin
- Occupation
- PE (Retired) - Power Systems
It appears you are really asking if the rebar, encased in each wall, should be bonded to the support columns. My answer would be no, just like the rebar in the roadway and the sidewalks does not need to be bonded to anything. My guess is that the construction of the steel support columns is sufficient to have them act as independent grounding electrodes, just like building columns do.
- Location
- Lockport, IL
- Occupation
- Retired Electrical Engineer
Every varying magnetic field anywhere in the universe will induce a voltage, and possibly a current, on every piece of conductive material anywhere else in the universe. The magnetic field generated by the transformer in your electric shaver will induce a current in the stapler on my desk. But generally, the currents are so small that they cannot even be measured, and do not present a safety concern.
So yes, the magnetic field generated by a transmission line that crosses over a concrete wall with rebar and metal support posts will, indeed, generate a current in that wall. The amount of current will depend mostly on geometric considerations (e.g., distances and angles). In order to get a calculated value for the amount of current, you will need to hire a professional engineer. I will repeat, however, that doing a better job of attaching the wall to planet Earth is not going to change the amount of current generated in any metal portions of that wall. "Proper and adequate grounding" will not shunt all current into the dirt, thus protecting any passers by from a possible shock, and is therefore a meaninless phrase.
jumper
Senior Member
- Location
- 3 Hr 2 Min from Winged Horses
- Location
- Bremerton, Washington
Its possible that there may be some induced currents, or more likely voltage with no current. south of here there is a home depot with a parking lot under 300 kV lines, the parking lot is in the line easement.
There are overhead wires connected to luminaire poles and then a big underground grid, all of this is to bleed off any static charge.
its not to trip the breaker if one of the lines fall.
The utility whose lines you are under should be able to point you to an solution.
There are overhead wires connected to luminaire poles and then a big underground grid, all of this is to bleed off any static charge.
its not to trip the breaker if one of the lines fall.
The utility whose lines you are under should be able to point you to an solution.
- Status