Using Power mode to locate power cables

Follow Avatar Phil Hembery
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Power mode on the C.A.T4 can be used to locate power signals that may be radiating from a power cable.  Power signals are sometimes referred to as 'passive' signals because they already exist on power cables and have not been applied by the person attempting to locate the power cable.

To locate power cables using the C.A.T4 in Power mode, the following conditions must be met:

  • Power mode selected on C.A.T4
  • Power cable is live
  • Power cable is connected to a load

Some users believe a power cable only needs to be live to be detected by a C.A.T4 but unfortunately that is not the case and is one of the reasons why some power cables are involved in cable strikes.

For instance, take a street light cable as an example.  During the day the cable feeding the streetlight is live but as the light is off there is no load so no current flows along the cable and as a result no detectable signal will radiate from the power cable.  In the evening the same live cable to the streetlight will now have a load as the light is on, current flows along the power cable and a detectable signal will radiate from the power cable.

Another consideration is the load or sometimes expressed as demand.  The amount of load on the power cable will effect the amount of current flowing along the power cable and ultimately the size of the signal radiating from the power cable.  Take a power cable feeding a garden shed running a low power light bulb or a house with virtually all appliances switched off.  In both cases, the load would be small resulting in a small signal radiating from the power cable which may make it difficult to locate the power cable, particularly if the power cable is buried fairly deep.