High (33 kHz)

High frequencies can energize the parts of the utility system that typically are not energized by lower frequencies and would otherwise be unlocatable: stubs, dead-ends, and poorly grounded laterals. This frequency range can also help you locate through high resistant rubber insulating pipe joints or broken tracer wire because it can penetrate the gap and still impose signal on the further side of the conductor. They also induce well.

The drawback to this currency range is this range bleeds heavily into the ground surrounding the conductor, which significantly reduces it's range. Higher frequency signals also couple more readily onto nearby conductors. As a general rule using higher frequencies in congested areas increases signal distortion causing greater confusion. This of course could result in incorrectly marking the target utility. Care should always be taken to minimize distortion.

Very High (262 kHz)

Frequencies in this range are most often used as a last resort on highly resistive circuits that can't be located with a lower frequency. These frequencies penetrate the soil easily, energizing all nearby conductors. They are very good inductively but because they energize almosr everything they can make the locating envirinment confusing. Very high frequencies also bleed heavily to ground, which significantly limits the distance they can travel.