How We Find What's Buried
Radio-detection utility locating, explained simply: a transmitter, an invisible magnetic field, and a receiver that listens.
Simplified illustration for explanation. Not to scale.
Three parts, one job
The transmitter makes the line hum
We clip a small box to the pipe or cable (or set it on the ground above it). It pushes a tiny, safe electric signal down the line, at a frequency we choose, like tuning to one radio station.
Electricity makes an invisible field
Whenever electricity flows through metal, a magnetic field wraps around it. It's the same force that swings a compass needle. The field is strongest right next to the line and fades as you move away.
The receiver finds the loudest spot
The handheld receiver has antenna coils that sense the field. We sweep it side-to-side. The beep peaks directly over the line, and that is where we paint the mark. Comparing two antennas gives an estimate of depth.
How close is “close”?
The tool tells us where the line is. It does not measure to the inch.
What the tool can tell us
- Where the line runs: its path across the ground, marked with paint or flags.
- About how deep it is, as an estimate read from the receiver.
- Which line it is, because our transmitter's frequency is the one we're listening for.
What it cannot do
- It is not a survey instrument. It does not give inch or sub-inch positions.
- Nearby pipes, bends, tees, and wet or rocky soil can bend the field and shift where the peak reads.
- Plastic pipe or fiber without a tracer wire carries no signal at all, so it can't be heard this way.
In good conditions the locator reads within roughly 5% of depth (a line 4 ft down → a few inches). Real ground is messier. Louisiana's dig law builds in an 18-inch tolerance zone on each side of the mark precisely because a locate is a close estimate, not a survey.
Call 811 before you dig. It's free, and it's the law.
One request to Louisiana 811 (the Louisiana One Call center) notifies every utility with lines near your dig site, including AOP Fiber. Each one sends a locator to mark its lines at no cost to you.
- Request a locate. Call 811 or 1-800-272-3020, or submit the request online. Emergency requests are taken 24 hours a day.
- Give two full business days. Louisiana law requires at least 48 hours' notice before you dig, not counting weekends and holidays.
- Respect the marks. Dig by hand, carefully, within 18 inches on either side of any marked line. That strip is the tolerance zone in Louisiana's dig law (La. R.S. 40:1749.14).
The 811 ticket is what dispatches our locator. Requests go through Louisiana 811, not through AOP directly.
Take it with you
The same explanation on a single printable page, ready to attach or hand out.
Download the PDFPrepared by AOP Fiber Internet · Advanced Office Products, Lake Charles, LA. Questions about a locate on your property? Contact us.