Depth Measurement 45º Angle Method
Move to a location where you want to measure depth. Stay at least 15 feet away from Transmitter. Move
Receiver left to right across path until cable is located. Mark path on the ground as precisely as possible using
the Null Method.
Place Receiver on the ground with LCD meter facing up. Position unit so the Bubble Level on top of meter is
centered (45º). Pull Receiver away from cable path (at 90º to the cable path) keeping Bubble Level centered.
When Receiver indicates a Null reading, mark the location of the Receiver’s foot. The distance between the
Receiver and the cable path is the depth of the pipe or cable.
A false depth reading may be caused by nearby buried metallic objects, such as a second cable, pipe, sewer,
fence or railroad track. Confirm depth measurement by repeating the above steps on opposite side of pipe or
cable. A variance greater than 5 inches in depth measurement may indicate the presence of additional buried
cables, pipes or other objects.
Tilted Magnetic Field Identification
When adjacent cables or pipes are present, they will sometimes create locating errors. Some of the Transmitter signal is
picked up by adjacent conductors and is redirected so it combines with the original signal. The result is a Tilted Magnetic
Field. This is often the reason that numeric depth readouts are sometimes created in error.
The operator can verify the accuracy of path locate by performing the 45º Angle Method locate on both sides of the cable
path. If the right and left side depth readings agree to within 5 inches, the path locate is accurate. If the two depth readings
do not agree, then
dig with care
. A closer locate would be halfway between the two outside depth locate marks.
This is an important technique that should be used to ensure the most accurate location possible.
10
