Every year, utility lines are struck once every 6 minutes in the United States. Some of those strikes happen during fence installation — because someone skipped a free phone call.
The AFA's Fence Installation School makes utility location the very first item in its site preparation module: "A request to the state's one-call service to mark utility lines must be made in advance of beginning installation." This isn't a suggestion. In every U.S. state, it's the law.
What's Underground?
Your yard likely has more buried utilities than you think:
- Natural gas lines — strikes can cause explosions, fires, and evacuations
- Electric cables — contact can cause electrocution and power outages
- Fiber optic / telecom lines — cutting these disrupts internet and phone service for your neighborhood
- Water mains — breaks flood your yard and street
- Sewer lines — damage creates sanitary hazards
- Irrigation / sprinkler lines — homeowner-installed, not always marked by 811
Gas and electric are the dangerous ones. Fiber and water are the expensive ones. All of them are avoidable.
The 811 Process
Step 1: Call 811 (or Submit Online)
Dial 811 from any phone in the U.S. — it routes to your state's one-call center. Most states also accept online requests at their one-call website.
When to call: The AFA specifies a minimum of 2 business days before digging. Some states require 3–5 business days. Call at least a week before your project to be safe.
What you'll need:
- Property address
- Type of work being done (fence installation)
- Planned dig area (describe or mark on your property)
- Start date
Step 2: Utilities Get Marked
Within the state's required response time (typically 2–5 business days), each utility company sends a locator to mark their lines with color-coded paint or flags:
| Color | Utility |
|---|---|
| Red | Electric |
| Yellow | Gas, oil, petroleum |
| Orange | Telecom, fiber, cable TV |
| Blue | Water |
| Green | Sewer, drainage |
| White | Proposed excavation (you mark this) |
| Pink | Survey marks |
Step 3: Respect the Marks
Markings indicate the approximate center of the line, with a tolerance of 18–24 inches on each side (varies by state). Per AFA training, when you encounter unexpected underground obstructions, stop digging and investigate. Relocating a post 6 inches is infinitely cheaper than repairing a gas line.
Step 4: Markings Expire
Per the AFA, utility markings last approximately 10 days before needing to be re-marked. If your project extends beyond 10 days, request a re-mark.
What 811 Doesn't Mark
Important: 811 only marks utility-company-owned lines. It does not mark:
- Sprinkler/irrigation lines — homeowner-installed, your responsibility
- Invisible dog fences — homeowner-installed
- Private utilities (propane lines, well lines, septic systems)
- Lines on your side of the meter (from the meter to your house)
The AFA training specifically notes that installers must "verify the location of all customer-installed utilities, such as sprinklers and invisible fences." Ask the homeowner before digging.
What Happens If You Hit a Line
Gas Line
Immediate danger: Gas leak. Risk of explosion and fire.
What to do: Stop work. Leave the area immediately. Do not use any ignition sources. Call 911, then the gas company.
Cost: $1,000–$10,000+ for repair. Plus potential fines, evacuation costs, and liability for injury.
Electric Cable
Immediate danger: Electrocution.
What to do: If you feel tingling or see sparks, drop the tool and move away. Do not touch the line. Call 911.
Cost: $500–$5,000+ depending on the damage. Power outage for your neighborhood.
Fiber Optic / Telecom
Danger level: Low personal danger, high cost.
Cost: $1,000–$25,000+ for fiber optic repair. A single fiber cut can disrupt service for hundreds of customers. The telecom company will bill the responsible party.
Water Main
Danger level: Low personal danger, significant property damage.
Cost: $500–$3,000 for repair. Water damage to landscaping and potentially foundations.
Legal Liability
In every U.S. state, the person who digs without calling 811 is liable for:
- Full cost of utility repair
- Cost of service disruption to affected customers
- Fines ($500–$50,000+ depending on the state and severity)
- Civil liability for injuries caused by the strike
- Potential criminal charges for willful negligence (hitting a gas line without calling 811)
If you called 811 and the utility was not marked or was marked in the wrong location, liability shifts to the utility company.
Contractor vs. DIY Responsibility
If you hire a contractor: The contractor is responsible for calling 811 before digging. Professional fence contractors do this routinely. If they skip it, liability falls on them — but the project delays and disruption still affect you. When hiring from the Fence Advisors directory, ask contractors about their 811 process.
If you're DIY: You are personally responsible. No exceptions. Call 811 before digging your first post hole. See our DIY vs. professional guide for the full comparison.
The Process Takes 5 Minutes
Call 811. Give them your address and project details. Wait for marks. That's it. The service is completely free — funded by utility companies specifically to prevent strikes.
Compare that to the alternative: a damaged utility line, a $5,000+ repair bill, potential injury, and your fence project delayed by weeks while repairs are completed.
The AFA puts utility location first in their training for a reason. It's the cheapest, simplest safety step in any fence installation — and the one with the most serious consequences if skipped.
Frequently Asked Questions
Is calling 811 required by law?
Yes, in all 50 states. It's a federal initiative with state-level enforcement. Fines for non-compliance range from $500 to $50,000+.
Does 811 cost anything?
No. The service is completely free to property owners and contractors.
How long do utility markings last?
Approximately 10 days per AFA training guidelines. If your project takes longer, request a re-mark.
What if my fence post needs to go where a utility line is marked?
Move the post. The AFA training advises relocating posts to avoid underground obstructions. A post shift of 6–12 inches is invisible in the finished fence but prevents a potential disaster.
Do I need to call 811 for a shallow project?
Yes. Some utility lines are buried as shallow as 6 inches (cable, telecom). Fence post holes are typically 24–42 inches deep — deep enough to reach virtually any buried utility.
Find a Fence Contractor Near You
Professional contractors handle 811 as part of their standard process:
- Dallas fence companies
- Atlanta fence companies
- Columbus fence companies
- Denver fence companies
- Phoenix fence companies
- Browse all fence companies →
Are you a fence contractor? Apply for FA Verified status →
*Utility location procedures per American Fence Association Fence Installation School site preparation module.*