Furthermore, National Codes specify the depth to which these lines must be buried below ground. Some low-voltage subterranean lines may be as shallow as 18 inches, whereas the majority of higher-voltage circuits will be at least 24 inches deep.
What is the depth of a utility trench?
- Call for Underground Locates at least 48 hours before digging at (800) 332-2344 or 811.
- Trenches must be at least 36 inches deep.
- If you can’t get a 36-inch depth, call Lane Electric’s Engineering Department at 541-484-1151.
- The following separations must be maintained if the trench is to be a common trench (shared with other utilities):
- There should be a gap of 24 inches between the gas and electric lines.
- Water and electric lines should be separated by 12 inches.
- Between the sewer and power lines, there should be a gap of 24 inches.
- Between communications and power lines, there should be 12 inches between them.
- If the trench will only be used for power, it must be wide enough to fit the conduit, which means a 4-inch ditch-witch trench will suffice.
- The conduit must be bedded with a minimum of 4 inches of sand if the trench is dug through hard, rocky terrain.
- Gray Schedule 40 electrical PVC must be used for all conduits.
- At any 90-degree curve, all primary conduit (7200V) must be 3 inches in diameter with 36-inch radius long sweeping elbows.
- For a 200 Amp service, the secondary (120/240V) conduit must be 3 inches in diameter, with 36-inch radius long sweeping elbows at any 90 bend.
- For a 400 Amp service, secondary (120/240V) conduit must be 3 inches in diameter, with 36-inch radius long sweeping elbows at any 90 bend. (As an example, see Exhibit A.)
- At any 90-degree bend, street or security lighting conduit must be 1.25 inches thick with 36-inch radius long sweeping elbows.
- In any one run of primary or secondary conduit between devices, there will be no more than 270 bends (3-90 bends or 2-90 & 2-45 bends).
- Mandrel proofing is required for all primary conduits.
- Details on mandreling can be found in Exhibit I.
- All primary and secondary conduits must be left with new 2500# mule-tape. Mule-tape must be able to move freely in conduit and have enough length (10 feet or more) beyond each end to allow for conductor installation. Mule-tape is available for free at Lane Electric.
- Specifications for transformers and primary or secondary junction boxes must be obtained from Lane Electric’s Engineering Department.
- (Common facilities are shown in Exhibits B-G.)
- Call Lane Electric at 541-484-1151 to schedule an inspection with the Engineering and Operations Department once the trench is dug and conduit is installed.
- The Trench can be back-filled after the conduit and the Trench have been inspected.
- It is not possible to install the conductor until the trench has been backfilled.
Note that no primary or secondary electric lines may be installed beneath a concrete foundation or slab.
How close can you dig to a utility line?
- Maintain a distance of at least 18 inches between your trenches or holes and the 811 markers. Because the equipment used to find subterranean wires aren’t always perfect, 811 standards recommend keeping holes or trenches at least 18 inches away from marked lines on both sides.
- If you built subterranean wiring or pipelines yourself, look up their location in your notes. Because most irrigation pipes and low-voltage wires are shallow, you can locate them by drilling a series of test holes by hand.
- Private location services can evaluate your property and locate any subsurface pipes, conduits, or wires for a fee. This is especially useful for private utility lines that were not installed by the government.
- Slowly dig. Irrigation lines and landscape lighting conduits and cables are not detected by 811 locating services, so dig slowly and deliberately, inspecting the excavation for unexpected pipes and wires on a regular basis.
Can I go as far as I can before dialing 811?
This figure comes from the Common Ground Alliance (CGA), and if it sounds disturbingly high to you, it’s because many people are unaware that they must call 811 before digging.
While the ground may not have thawed where you are, April is National Safe Digging Month, and it’s a good reminder to know what you need to do before breaking ground on this year’s projects.
According to data collated by CGA from various industry associations, there are more than 100 billion feet of subsurface utilities in the United States, so you can’t assume your customer’s property is free of them.
There is no limit to how deep a person can go before calling 811. CGA advises that any time you put a shovel in the ground, whether it’s to plant little shrubs or build a fence, you should contact because many utilities are buried just a few inches below the surface.
Even if an area has been designated previously, erosion and root system growth might change the depth or location of buried wires, so call each time you start a job.
Calling 811 is also not an optional chore, as every state has a different statute that requires people to contact before digging. While the amount of time you have to call 811 before digging differs by state, you can find your state’s standards here.
It is a frequent misperception that dialing 811 costs money; nevertheless, dialing 811 is completely free. Utility companies cover the cost to protect you, your staff, and your customers. When you don’t call, hit a utility line, and are held liable for the damage, the true expenses effect your business.
Some utility companies charge not just for the expense of dispatching a staff to repair or replace the damaged property, but also for the loss of service caused by the outage.
In recent years, some states have enacted penalties and fines to aid in the enforcement of the law. Mississippi passed a law in 2016 requiring first-time offenders to complete a compliance training course.
Second-time offenders within a five-year period must complete a training course or face a fine of up to $500 per offense. Malicious activities with the aim to destroy subsurface lines result in a training course and fines of up to $5,000 per event for third-time crimes in a five-year period.
Here’s how the 811 system works and what to expect:
- Two to three days before digging, call 811 or submit an online request to your local one-call center.
- The affected utility companies will be notified by the one-call center. Wait two to three days for the utility operators to react to your request (this varies by state). For each request, an average of seven to eight operators are notified.
- Verify that all of the operators who are affected have responded to your request. The process for confirmation varies by state.
- Dig around the designated locations with care. The majority of state rules prevent machines from being used within 18 to 24 inches of a utility that has been marked. Hand dig or use vacuum excavation if you need to dig closer.
Keep in mind that depending on the state, the locate ticket is only good for a set amount of time, and if you want to continue, you’ll need to call 811 for a re-mark.
Stop working immediately if one of your employees accidentally hits a pipeline. The processes that follow differ depending on the type of utility line hit.
When dealing with natural gas, propane, or petroleum lines, leave the area and contact 911 as well as the facility operator. Don’t do anything that could start a blaze, and make sure everyone is aware of the situation. Keep the public out by cordoning off the area. Stay away from the gas and do not attempt to repair the pipe on your own.
Warning everyone in the area, including emergency responders, that the ground and objects near the point of contact may be energized in the case of electrical wires.
If you have a radio or phone, call the electricity utility operator or the fire department. Otherwise, stay on the excavator and ask someone to call for utility and emergency help.
Those near the excavator or point of contact should keep both feet together and remain still. They must not come into contact with the excavator or the material. Only leave the excavator and the surrounding area after an official from the electric utility has declared it safe. If a fire, explosion, or other hazard requires quick evacuation, jump (not step) from the apparatus and land with both feet. Make sure you’re at least 25 to 30 feet away. Take no ordinary walking steps.
Notify the facility owner of any damaged communications cables, and do not study or stare at broken, severed, or disconnected fibers. Keep a safe distance away and barricade the area to keep others out.
Contact the pipeline operator after examining the situation and ensuring that nothing appears to be harmed. Minor nicks or dents can lead to major issues in the future.
If a homeowner has consulted you but intends to do it themselves, remind them that calling 811 isn’t just for professionals; anyone planning to dig must dial this number.
What’s the best way to dig around utilities?
Your power-digging work can start after you’ve called 811, waited the required time, and checked that all buried utility lines on your project site have been discovered and tagged, right?
No, not yet. Before working near an underground utility line, you must first dig around it to expose it and confirm its exact location and depth. The standards for hand-digging differ per state.
- Use hand tools or vacuum technology only within the tolerance zone, which is the width of the indicated utility plus 24 inches on either side of the outside edge in New York.
- Within 18 inches of either side of the indicated location of subsurface utilities in Massachusetts and Rhode Island, power digging is prohibited, and hand digging or other nonintrusive methods are required.
Dig with care
When hand digging near buried utility wires, take the following precautions to avoid damage:
- Use a shovel with a rounded or blunt edge. Pickaxes, mattocks, pry bars, and pointed spades are examples of sharp instruments that can gouge or puncture lines.
- Begin excavating to the side of the utility line that has been designated. As you approach the utility from the side, use a delicate prying motion to break up the soil.
- Proceed with caution. Make no assumptions about the accuracy of the marks or the utility depth.
- To remove soil, never pry against a utility line. Don’t use both feet to puncture the earth or stomp on the shovel.
- Not simply a tracer wire or warning tape, but the actual line should be dug up.
Avoid muscle tension by wearing suitable personal protective equipment (PPE). Instead of twisting your torso to move the dirt, turn your entire body by moving your feet. To avoid tiredness, alternate shoveling between your left and right sides and take rests.
Protect utility lines
Support all exposed utility lines with materials that will not damage the conduit or pipe or its coating. Cast-iron pipelines should be handled with caution. When the earth around or near natural gas mains is disturbed in any way, they are prone to harm. When your excavation may encroach on a cast iron natural gas line by crossing or simply running parallel to it, notify National Grid right away.
Follow these guidelines when it’s time to backfill:
- Examine exposed lines for damage and notify National Grid of even small scrapes or dents.
- Using a blunt-edged shovel, backfill under exposed lines by hand.
- To avoid damage as the soil settles around the reburied lines, remove any pebbles or concrete from the backfill soil.
Report ALL damage
A minor gouge, scrape, or dent in an electric conduit, a gas pipeline, or the coating of a pipeline could result in a catastrophic burst or leak in the future. Furthermore, if the tracer wire fitted with plastic underground natural gas lines breaks or is damaged during your excavation and is not fixed, future excavators and the general public are at risk since the plastic natural gas line cannot be detected.
Even minor damage to a utility line should be reported to National Grid right away so that technicians can assess it and make the required repairs. If you come across or come across an unlabeled line, don’t assume it’s inactive or abandoned. It should always be reported.
What happens if I dig and come upon a water line?
Calling 811 before you dig is the most important step you can take to avoid an accident. When homeowners and contractors dial 811, a team of experts connects them with a team of experts who notify the proper utility providers of the requester’s purpose to dig. A team of professional locators is then dispatched to the excavation site to use color-coded paint and flags to indicate the locations of subsurface utilities.
Fast Fact: An underground utility line is broken every 6 minutes because someone decided to dig before dialing 811.
Even a single line struck when digging can result in significant injury, fines, hefty repair expenses, and power interruptions. So, even if you’re only excavating a few inches underground, we strongly advise you to have your utilities marked so you don’t accidentally hit one. Calling 811 before you start your project, whether you’re hiring a professional or doing it yourself, is smart digging!
Is it possible to have both water and electricity in the same trench?
If you’re thinking about digging your own utility trenches, there are a few things to consider. Even while this is a fantastic approach to save money while getting your project started, it is critical that you do so securely. As a result, you’ll need the appropriate tools, equipment, and knowledge of local legislation. Keep in mind that codes differ from state to state, so you should check with your local city council or a utility company before getting started.
Is it possible to run electrical and plumbing lines in the same trench? Yes, you can; however, you must do so appropriately. Otherwise, you risk a few code infractions as well as posing a serious safety hazard. Because of the risks involved with this task, you should always seek the advice of a professional if you have any concerns.
Is it possible to have a water and sewer line in the same trench?
Water and sewer lines must be separated by at least ten feet and cannot be installed in the same trench. A minimum of two feet of space is required where a potable water line crosses a sewer line.
In Oklahoma, how deep are electric lines buried?
CITY OF OKLAHOMA
Public Service Company of Oklahoma rarely buries electric wires, even after a devastating ice storm. According to Stan Whiteford, the utility’s region communications manager, PSO buries power lines “to address specific operational difficulties such as voltage or capacity issues.”
PSO, for example, had a portion of line in Bartlesville a few years ago that was in an older established area with large trees. Because that neighborhood was supplied by an undersized substation, Whiteford explained, “we needed to upgrade the circuit.”
“The answer was not to go into the back yards,” he added of the improvement. “Those overhead lines were located in the middle of a forest.” Instead, the electricity cables were buried in front yards, “where they are considerably more accessible.”
Putting power lines underground is usually not cost-effective “on a large scale,” according to Whiteford.
“We convert from overhead to subterranean on occasion to improve voltage or capacity,” he explained, “but not purely for aesthetic reasons.”
The Oklahoma Corporation Commission assessed the cost of burying all electrical transmission and distribution lines in the state at $57.5 billion in a study conducted 12 years ago. That number is about nine times more than the fair cash worth of all public service electric firms in Oklahoma in 2020, and more than seven times greater than the $7.7 billion state budget set by the Legislature for Fiscal Year 2021.
In December 2007, a three-day ice storm knocked out power to more than 600,000 homes and businesses across the state, many for several days and others for more than a week, and was blamed for 29 storm-related deaths.
As a result, in 2008, the Corporation Commission conducted a study comparing the costs of underground power lines vs overhead power lines.
The commission’s staff gathered data from PSO and Oklahoma Gas & Electric Co., the state’s two major investor-owned electric companies, as well as the Office of Emergency Management and Edmond Electric. The Public Utility Division of the commission also requested information from all retail electric utilities and cooperatives in Oklahoma.
The staff also met with members of the Oklahoma Climatological Survey to address the impact of severe weather and the regularity with which it occurs, both of which would likely continue to negatively impact Oklahoma’s electrical plant and customers.
A study by the Edison Electric Institute was included in the commission’s examination, as were studies undertaken for and by the states of Florida, Maryland, North Carolina, Virginia, and Michigan.
The Oklahoma Insurance Department, the Oklahoma Tax Commission, the Department of Public Safety’s Highway Traffic Safety Office, and the state Department of Agriculture, Food, and Forestry’s Oklahoma Forestry Services were all contacted for information.
The Corporation Commission determined that the information gathered from the many in-depth studies that were analyzed “clearly indicated that mandating electric utilities to underground all of their facilities is generally not a practical solution.” The expense of undergrounding all transmission and distribution facilities would be in the billions of dollars, with a major impact on customers.
Severe storms cause broad damage to overhead electric facilities, but the most widespread damage occurs when severe icing occurs in conjunction with high winds. Each cubic foot of ice weighs 57 pounds.
When ice builds on an overhead line amid heavy winds, it takes the shape of a “wing” and gives the electric line “lift,” prompting it to begin moving. Electric lines can move dramatically up and down in extreme circumstances, which is referred to as a “galloping line.” The combination of heavy ice and wind moving overhead electric lines is often enough to snap the supporting poles, resulting in customer outages.
Because of the three-day ice storm in October, PSO had to rebuild around 250 utility poles and 713 cross-arms, as well as more than 89,000 feet (nearly 17 miles) of electric wires.
Cooperatives can get help from the Federal Emergency Management Agency for storm losses under federal law.
Electric utilities, on the other hand, are unable to insure their power lines in the event of a storm. Following devastating losses in Hurricane Andrew and subsequent widespread disasters, the private insurance sector has stopped offering inexpensive policies to cover catastrophic weather-related losses suffered by power companies.
The Corporation Commission stated that “this information was provided through telephone conversations with multiple insurance companies and utility risk managers.”
The following are some of the potential advantages of burying power lines:
- enhanced aesthetics, thanks to the removal of unattractive aerial wires and poles (however all utilities that share space on a pole with a power line, such as cable TV and internet providers, must coordinate efforts and bury their lines as well);
- Wind, rain, and ice storms cause less damage to facilities, resulting in fewer outages;
- Day-to-day and following storms, there are fewer lost electrical sales;
- fewer animal-related damages (such as the grass fire that broke out near Medicine Park on Sunday, which was started by a squirrel on an electric line);
- Underground electric networks have much fewer outages than aerial power lines;
- lower expenses of vegetation management (from trimming overhanging tree limits). According to information collected by the Corporation Commission from investor-owned and regulated electric cooperatives, the utility firms spent an estimated $63 million on vegetation control in 2007.
- In 2008, the cost of burying just electrical distribution lines in Oklahoma was predicted to be $8,800 per person, or $16,600 per person if both transmission and distribution lines were buried. Oklahoma had roughly 8,551 miles of main distribution lines and approximately 34,600 miles of lateral distribution lines at the time, according to electric utilities and cooperatives.
- The cost of burying high-voltage transmission lines is 10 to 14 times that of overhead cables per foot (wires). The cost is determined by the line’s voltage and the project’s location, which includes whether the line is installed in an urban, suburban, or rural setting, as well as if the site contains sand or clay soil or if the line must be trenched through rock.
- Despite the fact that electric lines are buried at least 48 inches below earth, the chance of severing a power line during ordinary excavation work grows, posing a serious risk of injury or death.
- The Corporation Commission staff pointed out that dig-ins are particularly dangerous for heavy-equipment operators as well as home gardeners.
- Higher voltage lines may need to be encased in concrete to prevent them from excavation damage and the risk of injury or death from dig-ins. According to officials, typical excavations for high-voltage cables are 5 to 8 feet deep and 4 feet wide.
- Overhead conductors designed to deliver the same amount of power are substantially thicker and heavier than underground wire.
The commission staff wrote, “The pricey design is important to avoid water damage and meet insulation and heat dissipation standards.”
- The commission staff concluded that finding and correcting problems in subterranean transmission lines takes “considerably longer than it does to replace an overhead power line.”
All studies found that underground electricity lines have fewer outages per mile than overhead lines, although the commission staff concluded that when an outage does occur, “it obviously takes longer to repair if the line is buried.”
- Because a transmission line affects a far larger number of customers than a lower-voltage distribution line, any difficulties caused by an underground transmission line are much more serious “A distribution feeder line will result in significantly more customer outage hours than a distribution feeder line.
- Buried power lines may have a shorter life lifespan than above lines “As a result, future replacement costs for underground assets are anticipated to be greater.
Both PSO and OG&E emphasized during negotiations that overhead facilities have a life expectancy “The commission staff estimated a lifespan of 50 to 60 years, owing to the ease with which individual components can be replaced. However, subsurface facilities are expected to last a long time “30 years is a reasonable estimate.
- Impediments such as roads, driveways, above- and below-grade obstructions such as trees, soil stability and rock content, and the presence of other utilities can quickly increase underground expenses. Additionally, the difficulties in obtaining easements from property owners “may raise the expense of burying aerial power lines.”
- A “stranded asset expense” arose from burying an aerial power line before it had fully depreciated. It’s like “tearing down a house with an existing mortgage,” according to the Michigan Public Service Commission.
Regulatory commissions across the country have addressed this issue in the same way that PSO did in Bartlesville: “by addressing specific parts of the electric grid, such as poorly performing circuits, lines along road rights-of-way undergoing construction, all secondary line extensions, and so on,” the Corporation Commission staff wrote.