SURFACE and SOIL CONDITIONS
The type of surface and the type of soil that you are dealing with while locating underground cable faults both have tremendous impact on your ability to accurately locate buried cable faults.
CONCRETE
In most cases, cable faults that are determined to be under concrete surfaces such as driveways or sidewalks, are more effectively repaired by replacing the cable under the surface as opposed to excavating through the concrete. Concrete does not conduct electricity nearly as well as soil, and as such locating a cable fault through concrete can cause problems. By utilizing the Spitfire along the edge of the concrete surface, parallel to the cable path, we can usually narrow down the area where the fault exists. Once a smaller area has been detected, pour water on to the concrete to increase the conductivity of the concrete, and pinpoint the cable fault by placing the Spitfire probes on the wet surface and working the probes exactly the same as you would in any other case. Salt water works better than plain water in this case, but any liquid will do in a pinch. Natural breaks in the concrete surface can be used to your advantage as well. Look for cracks and expansion joints that provide a more direct path to the soil below. Remember - if you do not plan on excavating the concrete surface to repair the cable fault you do not need to spend a lot of time pinpointing the exact location of the fault.
ASPHALT
Asphalt and blacktop actually insulate the ground, so simply wetting the surface will usually not allow the signal from the Spitfire to reach the probes. The only effective method to locate cable faults under an asphalt surface is to drill holes through the surface, deep enough to reach the soil below. Filling the holes with water will provide an even better signal reaching the Spitfire probes. In cases of large asphalt or blacktop areas you will want to separate the area in to longer sections than you ordinarily would while using the Spitfire to avoid drilling too many unnecessary holes. Any holes that you drill through the asphalt should be patched immediately to prevent future damage caused by water getting under the surface.
FROZEN GROUND
Frozen soil conducts electricity much the same as asphalt, which is to say that it does not conduct electricity very well at all. Similiar methods must be used to locate underground cable faults. The frozen ground must be penetrated in order for the Spitfire signal to reach the probes. This can be accomplished by drilling the soil, or by hammering the probes in to the ground. To detect the strongest signal, the probes should reach past the frozen layer. Also remember that the ground rod used to provide a return path to the Spitfire must also penetrate the frozen layer and reach the soil beneath.
DUCT or CONDUIT
There is usually no need to pinpoint cable faults in cases where the cable is installed in duct or conduit. In these situations, the section of duct or conduit where the break exists needs to be identified and a new section of cable should be pulled in. This is one of the primary reasons for installing cable in duct or conduit in the first place. Conventional underground cable fault locating equipment cannot locate a fault that is in a duct or conduit because the cable is isolated from the ground, thus eliminating a return path to the equipment. However, if the cable in the conduit is broken because the duct or conduit itself has been damaged you may be able to locate the point of damage with the Spitfire. This is especially true if the conduit has filled with water or mud. Remember - the pulse generated from the Spitfire must have a return path to the ground rod for it to be detected. The same is true for most common underground cable fault locating equipment. Broken cables that reside in duct or conduits are most often located with the use of a cable tracer, with the damage being in the area where the signal from the cable tracer is lost.