Depth Measurement 45º Angle Method
Move to the location you want to measure depth. Stay at least 15 feet (4.5 meters) away from the
T
RANSMITTER
. Move the R
ECEIVER
left to right across the path until the cable is located. Mark the path on the
ground as precisely as possible using the Null Method.
Place the R
ECEIVER
on the ground with the LCD meter facing up. Position the unit so that the BUBBLE
LEVEL on top of the meter is centered (45º). Pull the R
ECEIVER
away from the cable path (at 90º to the cable
path) keeping the BUBBLE LEVEL centered. When the locator indicates a NULL reading, mark the loca-
tion of the locator’s foot. The distance between the R
ECEIVER
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 the depth measurement by repeating the above steps on the oppo-
site side of the pipe or cable.
A variance greater than 5 inches (12.7 cm) in depth measurement may indicate the presence of additional
buried cables, pipes or other objects.
14
Tilted Magnetic Field Identification
When adjacent cables or pipes are present, they will sometimes create locating errors. Some of the
T
RANSMITTER
signal is picked up by the adjacent conductors and is redirected so that 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 (12.7 cm), 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.
