The RD8100 locator provides automatic depth of buried cables, pipes and sondes and when the locator is correctly orientated above the target line or sonde.
Current readings are also displayed simultaneously if the locator is orientated correctly (feature not available in sonde or passive frequency modes).
Depth and current readings are automatically displayed simultaneously, but if the locator is not correctly orientated neither reading will be displayed.
Depth range and accuracy vary depending on the makeup and type of target utility (e.g. cable, pipe or sonde), its depth and external environmental factors like electromagnetic noise, ground conditions and interference.
WARNING: The accuracy of depth measurement is subject to a number of factors and is meant as a guide only. Never use the depth measurement to define mechanical digging depths. Always follow local safe digging guidelines.
The depth measurement is to the center of the pipe, cable or sonde. The best readings are typically detected from ‘active’ signals output by a transmitter rather than from passive sources.
The RD8100 locator is capable of determining cable depth when locating some passive power signals. However passive signals on lines are less suited for measuring depth because accuracy can be compromised by interference- e.g due to the passive signal being present on more than one line.
WARNING! Do not make depth measurements near bends or tees in the line. Go at least 5m (16ft) from a bend for best accuracy.
TruDepth and Compass
It is important to note that the RD8100 locator will only display depth and current (in applicable modes) when the locator is correctly orientated above the target line, cable or sonde. To ensure the locator is correctly orientated, use the Compass feature.
When locating lines, make sure the Compass display is in the North / South orientation position.
When locating sondes, make sure the Compass display is in the East / West orientation.
To minimize signal distortion, do not apply the signal by induction. If Direct Connection or signal clamping is not possible, place the transmitter in induction at least 15m (50ft) from the point of any depth measurements.
Depth measurements may not be accurate if there is audible interference or if part of the transmitter signal has coupled to a nearby line.
Confirming the Peak position coincides with a Null position indicates that the position is suitable for making a depth estimate.
Check a suspect or critical depth reading by lifting the locator 50mm (2”) above the ground and repeating the measurement. If the measured depth increases by the same amount it is a good indication that the depth reading is correct.
When locating for a conductor or sonde, depth measurements should be precise to ±3% if conditions are suitable. However, you may not always know if the conditions are suitable so the following techniques should be used to check critical readings:
This paragraph describes several quick and easy ways of verifying that the depth reading on the locator when used for markers or conductors and sondes is within acceptable limits.
Refer to this if you are getting inaccurate depth readings from a cable or pipe for which you know the approximate depth. Inaccurate depth readings could be the result of the locator picking up a stronger signal such as another cable or pipe running in close parallel to the target pipe or cable.
There are two ways of checking the calibration of the locator in the field. Both methods require the use of a transmitter:
Place the transmitter on top of a non-metallic object, 18” / 500mm in height or more, on the ground and away from any buried lines. Switch the transmitter on in induction mode. Hold the locator with the blade horizontal and pointing towards the front of the transmitter and approximately five meters from the front of the transmitter.
The locator can be considered accurate if the difference between the depth reading on the locator and the distance measured with the tape is less than 10%.
NOTE: The accuracy of depth measurement is subject to a number of factors and is meant as a guide only. Exercise caution when performing any excavation.