LOCATING TIPS AND TRICKS

INDUCTIVE SPILLAGE – WHAT A STUPID NAME.

No matter what you know it as, Inductive Spillage, Dropping the Box, Non-Metal-to-Metal, using the transmitter in the inductive mode without the use of the clamp, can in certain situations be the only method available to apply our signal.

Unfortunately, with this method you usually need to use a higher-than-normal frequency, which can cause bleed-over culminating in signal distortion, creating a non-round field, and thus an inaccurate locate.

There are several things available that will reduce and/or avoid bleed-over. Here are some tips that may assist, depending on the situation, some of these techniques may work better than others.

WORK SHORT DISTANCES.

Utilities that are running adjacent to your target line will, in most cases carry some signal, many times these adjacent running utilities will become the return paths from the target line to the transmitter. Remember there are only 3 things that we can say about locating that happens all the time:

▶ The electromagnetic field wants to leave the Target Line equally in all directions – in other words it wants to be round.

▶ The amount of signal that leaves the transmitter MUST return to the transmitter.

▶ Current will always follow the Path of Least Resistance. At first, the signal strength from the target line will be stronger, than that on the adjacent line. As you walk down the line the signal will weaken to the point that it becomes equal in strength with an adjacent conductor.

The solution is to mark the last known confident spot of the target line and then move the transmitter to that position, some people call this Leap Frogging. This will re-strengthen the signal on the target line and let you continue with a confident locate.

OFFSET THE TRANSMITTER.

Another handy tip is to offset the position of the Transmitter. In a lot of cases, you can simply move the transmitter slightly to the opposite side of an adjacent conductor. Because of the way that the signal transmits through the ground, a greater amount of the signal will be on the Target Line, whilst less signal will get to the adjacent line. Whilst this will put a slightly weaker signal on the target line, there will be a significantly weaker signal on the adjacent conductor.

NULL OUT THE UNWANTED LINE.

When all else fails, try Nulling Out the Unwanted Line. This is a great tip that can be used when there are two lines causing confusion. You can place the transmitter on its side over the unwanted conductor. Because of the shape of the signal leaving the transmitting antennae, imagine the shape of a Sherrin AFL or NRL football, there is no signal leaving the transmitting antenna, at the two ends, again imagine the pointy ends of the football. This will put a signal on the target line and make the unwanted adjacent line nearly disappear.

Foot Note: For all you Radio Detection users out there. Have you ever wondered what the small fold out appendix is on the Transmitter. It is there so that the Transmitter will sit, squarely when you tip it on its side to “Null Out” an unwanted conductor.