Professor Kerr
EN101-23
November 29, 2011
Overhead Power Lines Should Remain
Almost every single time a major storm strikes a city, the question as to whether power lines should be buried or remain overhead is brought up (“Underground or“). The recent October snowstorm knocked down trees which caused damage to a lot of power lines and utility poles and caused people to question why the power lines aren‘t yet underground and out of harm‘s way (“Underground Power“). Although power lines may remain above ground, there is a movement across most of the country that wants to bury power lines to prevent outages that can be caused by bad weather (Cassidy). Unfortunately for those in favor of underground power lines, the damages caused by the bad weather won’t tip the scale in favor of burying power lines (Cassidy). Even though power lines may remain above ground, there are advantages and disadvantages for both systems (“Underground or“). However, the technology involved with underground power lines is advancing, but it still doesn’t outweigh the disadvantages (“Idaho“). It is my personal opinion that power lines remain above ground for the time being. Overhead and underground power lines differ in the cost of installing the power lines, how the two different systems are installed, and the reliability of each system.Using overhead power lines and taking the necessary steps to install overhead power lines saves more money than burying power lines and making the adjustments that are in association. Overhead power lines have lower costs, higher installation rates, and are built faster providing earlier services (Rowe). According to Connecticut Light and Power (CL&P), overhead power lines cost about $800,000 a mile ,whereas an underground system would cost around $3.5 million per mile (Cassidy). The cost for trimming trees for an overhead system is substantially less than the cost for construction of an underground system (“ETL“). Also, the maintenance of the overhead system also costs a lot less than the maintenance for an underground system (“ETL“).
Underground power lines cost more, but they are less prone to weather damage. Dan Riedinger from the Edison Electric Institute informs that installing underground power lines would only cost an additional $10,000 per mile in a country-like setting (“Underground Power“). The cost could be considered more reasonable in areas where the geography would cause more outages in an overhead system (Cassidy). William Tong, state representative of Connecticut, said, “I think everybody would rather we were able to bury them underground[.] The problem is the level of cost and construction that comes along with it . . . It’s thousands and thousands of dollars per foot” (Cassidy). Many people want power lines to be buried, but the work and cost that comes with it is too great. The economic benefits of installing underground power lines seem great enough to overthrow the cost that comes with the installation (“ETL“). The cost of installing underground power lines can be calculated from what the terrain is like, the placement of the power lines, other underground facilities, the time of day, the design, and a number of other factors (“American“). Burying power lines can save some money since it reduces the exposure to trees that would need to be trimmed in order to install an overhead system (“ETL“). However, burying power lines would still cost more than installing the power lines on poles.
Cost is one of the major differences between overhead and underground systems. Installing an underground system can cost up to ten times as much as installing an overhead system (“American“). The repairs for an underground system also cost more and require more time than repairs made to an overhead system (“Underground or“). Mitch Gross, a CL&P utility spokesman, said, “We have many inquires from the towns we serve about relocating power lines underground, which typically involve aesthetics and storms, but once they learn of what it would cost them and what is involved, they put those ideas aside” (Cassidy). Once people learn what the requirements and costs of installing an underground system, they usually change their minds. Gross also mentions, “Underground power lines are susceptible to heat buildup, and the road salt used for ice control during the winter can eat away and weaken the protective wrapping around the underground cable ” (Cassidy). Jim Owen, a spokesman for Edison Electric Institute, says,
There are a number of different threats out there that could pose a threat to overhead lines like ice storms and in the West you've got brush fires' high winds that are problems for overhead infrastructure [.] Some of those same threats could also impact underground lines, so there is no silver bullet to solve everything (Cassidy).
Both Owen and Gross are saying that the power lines aren’t 100% safe even though they’re underground. The costs of repairing lines on an overhead system are also lower than the installation cost of an underground system (“Ottawa“). There is a little more difficulty in repairing underground power lines which can be exposed to flooding (“Ottawa“). Burying the power lines may have economic benefits that seem great enough to overthrow the costs, but in reality, the benefits are out of the question when the difference in costs is viewed upon (“ETL”). Installing power lines in overhead systems is the most affordable choice (“Idaho“).
Installing overhead power lines saves time and resources when repairs or improvements need to be made. When a power line needs to be repaired, it can be done much faster if it was in an overhead system versus an underground one (“Idaho“). The American Transmission Company (ATC) fix problems on an overhead system or improve it without causing too many problems (“American”). The ATC also tries to improve an area by placing smaller wires on the same poles (“American”). Speed is another benefit of installing overhead power lines as well (Rowe). Usually at least one kilometer of wire can be installed on an overhead system a day and if the weather conditions are really great, up to five kilometers of wire can be installed (Rowe).
Burying the power lines allows the location where the power lines are to appear cleaner and more pleasing to the eye. Underground power lines aren’t in the way and are protected from conditions that could harm overhead systems (“Underground or“). Buildings and other structures can also be built in locations that would be unavailable if an overhead system was present (“CCBDA“). Firefighters have more freedom to work and more room for their equipment (“CCBDA”). Vehicular accidents are also reduced, and underground systems make it harder for people to be exposed to the wires (“CCBDA”). Although underground systems are usually out of sight, they can be more visible when vegetation management comes into play (“Idaho“). When power lines are buried, trees don’t have to be trimmed or cut, and this action not only saves money but also saves the aesthetic value of the tree (“ETL“). Buried power lines can still affect a tree, but instead of at the top where an overhead system would have an effect, the underground power lines have their effect on the roots (“ETL“). The impact underground systems have on a tree can be reduced but not eliminated by boring a hole through the roots instead of using an open trench construction (“ETL“). Boring raises the cost of installing an underground system though (“ETL“). Underground systems are usually installed when new areas are developed and structures are being built (“Underground or“). Careful engineering is mandatory when placing the lines in order to make sure the lines are safe and reliable (“American”). The lines in the underground system are required to be in individual conduits which are encased in thermal concrete and surrounded by certain thermal materials (“American”). A fiber optic cable is also required in order to protect the lines and control devices which, in turn, protect the system (“American”). Splice vaults, which are large concrete encased structures, are needed every 1,000 to 1,600 feet in an underground system (“Idaho“). Underground power lines need to prevent contact with trees in order to prohibit interference with the underground system, and roads need to be managed so underground systems can be accessed for maintenance and repair (“Idaho“). Underground systems are also equipped with a spare conduit which can be used to replace a damaged cable or pipe without reopening the entire trench and, as a result, saves more money and time and doesn’t interfere with the environment as much (“American”). Underground systems consume less heat than overhead ones, and the soil, the depth of the system, and any nearby structures affect the wires’ ability to get rid of the heat (“American”). However, new underground systems can dissipate heat better than older overhead ones (“American”). Underground power lines make more sense and are the more reasonable choice where the area of installation is in heavily populated areas or near airports (“American”).
How the two different systems are installed determines the time it takes to get the systems set up and the ease of making repairs and improvements. Overhead power lines can be installed on poles much faster than digging trenches to install the power lines underground (Rowe). It’s harder for the ATC to make improvements on an underground system than it is on an overhead one (“American”). Underground systems are not only more expensive but also harder to install and operate (“Idaho“). It’s also harder to make repairs in an underground system since it takes more time to find the problem, dig up the area where the problem is located, and fix it than it is to fix a problem in an overhead system (“Idaho“). Underground systems also use more equipment for installation purposes and generally need more substations (“Idaho“). In addition, when a tree is affected by an electrical distribution system, more damage is received from an underground system (“ETL“). Boring can usually reduce the damage done to a tree, but if boring is not available and an open trench construction has to be used instead, a decent amount of damage can be done (“ETL“). The damage done to a tree can be great since the roots of the tree are located within the top four feet of the soil, and depending on the situation, part of the tree could even be killed (“ETL“). Therefore, the most damage can be done to a tree from using an underground system.
Overhead power lines have a higher reliability rating than underground ones. Overhead power lines tend to be more reliable because of their design and since most of the lines are set up with a backup source just in case one of the lines were to lose power (“ETL“). Since the wires in an overhead system are only supported by poles, the cables need to be strong ,whereas the underground cables just lie inside a trench (Rowe). The overhead power lines also have to be strong enough to support the extra weight caused by wind and ice (Rowe). An overhead system can last up to 100 years, yet an underground one may only last around twenty years (“Idaho“).
Underground power lines aren’t made as strong as overhead power lines since weather doesn’t have to be considered as much when installing the underground power lines. The lines can also be more reliable during a storm and are less likely to witness an outage (“Ottawa“). Underground power lines also don’t require as much maintenance (“CCBDA“). Although, the reliability of underground systems increases as repairs and upgrades are made to the electric infrastructure (“Underground or“).
With the exception of storms, overhead systems are more reliable than underground ones. Overhead systems received an excellent reputation for security and reliability because of the wires that have been in use since the 1980s (Rowe). It’s also easier to repair power lines in an overhead system (“Underground or“). The faults in an underground system are harder to find which causes more time to be taken in order to fix the problem (“Underground or“). Conductor heat buildup, underground water, and bacteria are a few of many factors that cause underground systems to be less reliable (“Idaho“). Underground systems also need bigger cables in order to carry the same amount of capacity as an overhead system (“Idaho“). Overhead systems may be more prone to weather damage, but they are also far more reliable (“Underground or“). And underground systems may be less prone to weather damage, but their problems are also much more difficult to find and more time consuming to fix (“Idaho“).
Costs, installation, and reliability greatly differ overhead systems from underground ones. When it comes to cost, overhead seems the more reasonable choice unless the area where the system will be installed doesn’t have enough room for an overhead system. Underground systems also take longer to install and require more work to ensure safety and reliability. The main benefit of an underground system is the reduction of trimming or cutting down trees and the cleaner and neater view of the area. Overhead systems are also more reliable than underground ones unless there is a storm. Depending on the severity of the storm, underground systems could be more reliable. If it’s just a small storm and there is not a threat of flooding, overhead systems are more reliable. If there’s a major storm and the threat of flooding isn’t present, underground systems are more reliable. It all depends on the circumstances. Still, overhead systems are the better choice when costs, installation, and reliability are being viewed.
Works Cited
American Transmission Company. Web. 11 Nov. 2011. <http://www.atcllc.com/IT5.shtml>.Cassidy, Martin B. "Underground Lines Can Inspire Sticker Shock - Connecticut Post." CTPost.com - Connecticut Post. Web. 23 Nov. 2011. <http://www.ctpost.com/news/article/Underground-lines-can-inspire-sticker-shock-2154315.php>.
“CCBDA Publication 21E: Section 3 - Advantages of Underground Cables." Canadian Copper and Brass Development Association. Web. 11 Nov. 2011. <http://www.coppercanada.ca/publications/pub21e/21e-Section3.html>.
“ETL - Impacts of Overhead vs. Underground Construction - Talgov.com." Talgov.com - The Official Website of the City of Tallahassee. Web. 23 Nov. 2011. <http://www.talgov.com/you/electric/tline_construct.cfm>.
“Idaho Power - About Us - Our Power Lines - Overhead/Underground Power Lines." Welcome To Idaho Power. Web. 23 Nov. 2011. <http://www.idahopower.com/AboutUs/OurPowerLines/overheadUnderground.cfm>.
“Ottawa Power Lines Seldom Buried OpenFile." Community-powered News OpenFile. Web. 24 Nov. 2011. <http://ottawa.openfile.ca/ottawa/file/2011/07/ottawa-power-lines-seldom-buried>.
Rowe, Jim. "Using Overhead Distribution Lines to Carry Fibre Optic Cables." Www.bigsocietybroadband.coop. Web. 11 Nov. 2011. <http://www.bigsocietybroadband.coop/book/export/html/85>.
“Underground or Overhead Power Lines?" Carolina Country Magazine. Web. 11 Nov. 2011. <http://www.carolinacountry.com/storypages/howtos/underover/underover.html>.
“Underground Power Cables Too Costly, Experts Say CBS New York." CBS New York -News, Sports, Weather, Traffic and the Best of NY. Web. 11 Nov. 2011. <http://newyork.cbslocal.com/2011/11/03/underground-power-cables-too-costly-experts-say/>.