⚠ The Single Most Important Thing Post hole augers — both manual and power — are one of the most common causes of utility strikes by homeowners. A power auger can bore through a gas line in a fraction of a second before the operator even knows what happened. Call 811 first, every time, for every fence project.

Why Fences Are Higher Risk Than You Think

Fence post holes seem simple — 10 or 12 inches in diameter, maybe 24–36 inches deep. But that depth range puts you squarely in the zone where residential utility lines run. Secondary electric feeds, natural gas service lines, and cable/telecom drops are all commonly found at 18–36 inches below grade in residential areas.

Fence lines compound the risk because they often run along property boundaries — and utility easements are frequently located along the same property boundaries. That strip of ground next to your property line is exactly where utilities prefer to run, because it gives them access without crossing private land repeatedly.

Utility TypeTypical Depth (Residential)Common Near Fence Lines?
Natural gas service line18–24 inchesVery common
Electric secondary feed24–36 inchesVery common
Telecom / cable12–24 inchesVery common
Water service line30–60 inches (varies by frost line)Common
Irrigation mainline8–18 inchesCommon
Landscape lighting3–8 inchesCommon

Step-by-Step: The Right 811 Process for a Fence Job

  1. Plan your fence line completely before calling

    Know exactly where every post will go. The more specific your locate request, the more focused the locator's work. A vague "I'm installing a fence in my backyard" gets you a broad sweep. "I'm installing 14 posts along the east property line from the southeast corner to the back gate" gets you precision marking where you need it.

  2. Pre-mark your excavation area in white

    Before submitting your ticket, mark each intended post location with a white flag or white spray paint. This is technically optional in most states for residential projects, but it dramatically helps the locator know exactly where to look. A locator who can see your planned post locations will spend more time precisely mapping those exact spots.

  3. Submit your 811 ticket at least 3 business days before digging

    Call 811 or submit online at your state's one-call center portal. Give the address, describe the work ("installing fence posts, approximately 36 inches deep"), and include the full length of your fence line. Note any gate locations. Submit at least 3 full business days before you plan to start — more if your project starts on a Monday or after a holiday.

  4. Wait for all utilities to respond

    Check your ticket status online or via the confirmation number you receive. Every utility must either mark the area or respond as "clear" (no conflict). Do not start digging until all utilities have responded — not just most of them.

  5. Walk the fence line and photograph all marks

    Before any digging, walk the entire fence line and document all markings with photos. Note which color marks fall closest to planned post locations. This documentation protects you if a dispute arises later about whether lines were marked.

  6. Adjust post locations away from marks

    Any planned post location that falls within 18–24 inches of a utility mark needs to be moved. You have a few options: shift the post along the fence line, move the entire fence line slightly, or in some cases, leave a gap in the fence at that location (though this is rarely ideal).

  7. Hand dig any posts that must go near marks

    If a post absolutely must go within 24 inches of a mark (after exhausting adjustment options), hand dig only. Use a clamshell digger or manual post-hole digger. Go slowly, exposing the soil in thin layers. If you hit anything — stop, assess, do not force through.

What to Do When Utility Marks Are Right in Your Fence Line

This is the most common problem homeowners run into: the locator comes out, and the marks are right where the fence needs to go. Here are your realistic options:

Option 1: Shift the Post Location

The easiest fix. Move the affected post 2–3 feet along the fence line in either direction. You'll end up with a bay that's slightly longer or shorter than planned, but the fence integrity is maintained and you're away from the utility. This works for most residential privacy and split-rail fences where post spacing is flexible.

Option 2: Move the Entire Fence Line

If marks run the length of your planned fence (common along a property boundary with an underground easement), shifting the whole fence 2–3 feet inward may be the cleanest solution. You lose a little yard space but avoid a complex installation. This is especially worth considering for wood or vinyl privacy fences where you're already pouring concrete footings — you don't want those footings anywhere near utility lines.

Option 3: Call the Utility for Exact Depth

The color marks indicate the horizontal position of the line, not the depth. Call the utility company whose mark is in your way (use the code on the flag or paint to identify which company) and ask for the approximate depth at your post location. If the utility runs at 48 inches and your posts are only 30 inches deep, you may be able to proceed — but get this in writing or documented before digging.

Option 4: Surface-Mount the Post

For decorative or light-duty fences, surface-mount post brackets anchored to a concrete pad rather than buried posts are a legitimate alternative when utility conflicts make standard installation unsafe. These work well for aluminum, light wood, and chain-link fences but aren't appropriate for high-load applications.

Irrigation Lines and Invisible Dog Fences Along Fence Lines

Here's what 811 won't tell you: most residential fence lines also have private irrigation laterals running perpendicular or parallel to them (to reach individual zones), landscape lighting wire, and sometimes invisible dog fence wire. None of these show up on your 811 locate.

Before digging, also think about:

  • Are there sprinkler heads near the fence line? Irrigation pipes typically run from a nearby head to the next one.
  • Is there landscape lighting along the fence line? The wire run from fixture to fixture is private and shallow.
  • Did the previous owner have a dog fence? The wire loop could be anywhere in the yard, often running near the perimeter.

See Does 811 Mark Private Lines? for the complete guide on what to do about these.

Power Auger Safety Rules for Fence Posts

A power auger is efficient and makes fencing go faster. But near utility lines, it's dangerous. Rules:

  • Never use a power auger within 18–24 inches of any utility marking — use a hand digger for those holes
  • Know where your auger emergency stop is before you start
  • If the auger suddenly stops or jerks — stop the machine, don't try to power through
  • If you hear a pop, smell gas, or see sparks — release the auger, step back, call 911
  • Have a second person with you when using a power auger near any marked lines

What a Typical Fence Locate Looks Like

Most residential fence locates produce orange flags (cable/telecom is nearly universal in suburban areas) and sometimes yellow (gas service lines near the street side of the property). Electric marks are less common in the middle of a yard but very common along alley lines. Water is typically deeper and less of a post-hole concern unless you're in a frost-free climate where lines are shallow.

A typical suburban backyard fence locate along 100 feet of rear property line might produce: 2–3 orange flags (cable run), 1 yellow flag (gas service line near house), and a clear designation for the rest. This is manageable with minor post adjustments.

FAQ: Fence Posts and 811

Do I need to call 811 for just one or two fence posts?
Yes. The law does not distinguish between one post hole and 50 — any excavation requires a valid 811 ticket. The practical risk is the same: one post hole in the wrong spot can hit a gas line just as easily as 50. The call is free and takes a few minutes. There's no legitimate reason to skip it.
My fence contractor says they don't need to call 811 for post holes. Is that true?
No, that's not true. Professional contractors are subject to the same one-call laws as homeowners, and in most states are held to a higher standard of compliance. A contractor who skips 811 is cutting a corner that exposes both them and you to liability. If something goes wrong, their failure to call 811 may shift full fault to them — but you still have a damaged utility and an interrupted project. Insist on 811 compliance from any contractor you hire.
What's the deepest a fence post hole typically needs to go?
Standard guidelines call for fence posts to be buried 1/3 of their total length or to below the local frost line, whichever is deeper. In the South, 24 inches is often sufficient. In Minnesota or Maine, frost lines can be 48–60 inches. In frost-prone areas, you're digging into the same depth range as gas and electric service lines, which is exactly why 811 is non-negotiable for fence work in cold climates.
The locator marked a line right through my planned gate post. What now?
Gate posts are the highest-load posts in a fence (they carry the weight and swing of the gate) and need solid footings. If a utility mark is right on your gate post location, contact the utility whose line it is and ask for exact depth. If the line is deep enough and your footing won't conflict, you may be able to proceed — but get documentation. If there's a real conflict, shifting the gate opening 2–4 feet is usually easier than you think, and worth it for a safe, legal installation.
My neighbor's fence is already there — do I still need to call 811 for my fence in the same location?
Yes. The fact that a neighbor's fence exists nearby tells you nothing about what's underground at your specific post locations. Your project requires its own ticket regardless of what exists nearby. Additionally, your neighbor's fence may have been installed before certain utilities were placed, or in a slightly different location. Don't assume their installation serves as your clearance.
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Before You Dig Checklist (PDF)

Print-ready checklist for fence projects: ticket submission, private line check, post adjustment notes, and documentation steps.

Download Checklist

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