Your property is filled with utility lines running at different levels underground, including low-voltage electrical lines, cable lines, sewer pipes, water pipes, natural gas lines, and more. If you accidentally damage a line while digging, it can be both costly and dangerous. Fortunately, there are several effective and free techniques for locating underground utility lines before you begin digging.
How deep are electrical lines buried?
All utility lines can present a risk when digging on your property, but electrical lines are often the most concerning. The depth of buried electrical lines can vary from shallow low-voltage wires for pathway lighting to deeper high-voltage underground distribution lines running through utility easements.
Depth of low-voltage wire
Loose wires for pathway lighting may be only one to two inches deep or sometimes even at ground level. Most low-voltage lines up to 30 volts should be buried at a depth of at least six inches.
Depth of electrical lines on private property
Most electrical lines on residential properties are buried between 24 and 48 inches deep.
Depth of high-voltage cables
High-voltage cables carrying between 22,001 and 40,000 volts are generally buried at a depth of at least 36 inches. Cables carrying more than 40,001 volts are typically buried 42 inches or deeper. If these lines are present on a property, they are usually located within utility easements.
Digging around hot-water pipes
The bucket of a mechanical digger should never touch the plastic coating on a pipe. Damage to the coating or its joints can allow water or moisture to leak into the insulation and cause corrosion.
It is recommended to dig around district heating pipes in small sections. Pipes can become damaged under pressure if long sections are excavated at once.
For pipes with a diameter of 90 to 110 mm, digging more than 3 metres away from the pipe coating can increase the risk of pressure damage.
Pipes with a diameter of 140 to 160 mm may break under pressure if digging occurs more than 5 metres away from them.
For pipes with a diameter of 200 to 250 mm, there is a higher risk of damage if excavation takes place more than 10 metres away.
Tips for digging around utility lines
- Keep holes or trenches at least 18 inches away from 811 markings. The tools used to locate underground wires are not always perfectly accurate, so guidelines recommend keeping trenches or holes at least 18 inches away from either side of marked lines.
- If you have personally installed underground pipes or wires, check your notes or plans to determine their location. Most irrigation pipes and low-voltage cables are relatively shallow, so digging a series of small test holes by hand can help locate them safely.
- There are private utility locating services that can inspect your property for a fee and identify underground pipes, wires, and conduits. This can be especially useful for locating non-public utility lines installed by private companies.
Final thoughts
Taking the time to identify underground utilities before digging can help prevent serious accidents, expensive repairs, and unnecessary project delays. Using proper safety measures and understanding the location of underground lines will help protect both your property and the people working on it. Whether you are installing landscaping, fencing, or new plumbing, careful planning and preparation are essential for a safe excavation project.