Vi-Deeds Supplement to Underground Focus

Underground Focus provides this resource page devoted to pipe and cable locating instruments and topics. ViDeeds are video supplements to Underground Focus Magazine Deeds articles and provide further information or education on locating issues.

At regular intervals, Deeds and ViDeeds will focus on definitions of locating terms. These definitions will provide simple, and sometimes visual, explanations of industry terms.

Deeds Glossary
Reprinted from December 2008 Underground Focus Magazine

What is electromagnetic pipe and cable locating? The detection of magnetic fields produced by current flow on metallic pipes and cables.

60-cycle: alternating current whose frequency is 60 hertz.


Access point: a bare metal spot on a pipe or cable whereby one end of the conductive transmitting antenna is attached.

Access point: a bare metal spot on a pipe or cable whereby one end of the conductive transmitting antenna is attached. View photo.

Active: a receiver response to a magnetic field generated by the transmitter.

Air lock: any receiver reading created by the transmitter’s energy leaving the transmitting antenna and not the pipe or cable. View movie.

Alternating current: the type of energy produced both by an electric power plant and the transmitter; energy that flows in two directions.

Apex: the topmost part of a signal circle. View photo.

Attracting field: a magnetic field whose energy moves toward another field; this field is not circular. Audio frequency: another name for low frequency.

Audio frequency: another name for low frequency. View movie.

Bad current: with the receiver held stationary, a peak response that fluctuates considerably. View movie.

Bottom receiving antenna: the lower half of stacked peak antennas.


Circuit: when discussing electromagnetic theory, the name for current flowing on a conductor and through earth.

Close-end: the end of a line leg where the transmitter is located. View photo.

Close-end ground: a metal making contact with earth at the end of a line leg where the transmitter is deployed.

Coil: wire, usually copper, wrapped around a core in a spool-of-thread-type fashion. View photo.

Coil orientation: the positioning of coil windings within a magnetic field. View movie.

Common ground: a shared metallic grounding connection amongst cable systems. View movie.

Concentric signal circles: the transmitter’s energy that orbits the pipe or cable at all distances from the pipe or cable. View photo.

Conductive: transferring the transmitter’s energy onto a pipe or cable by employing a metal-to-metal connection between the transmitter and the pipe or cable.

Conductive transmitting antenna: a wire with two ends which connects the transmitter to 1) the pipe or cable and, 2) the earth.

Conductor: a name for a metallic pipe or cable when discussing electromagnetic theory.

Cross: a potential signal split on a piping system where the transmitter’s energy encounters three new line legs.

Current: the flow of the transmitter’s energy on a pipe or cable.

Current flow reading: a measurement on the transmitter of the amount of energy leaving the transmitter. View photo.

Current level: an assessment of the amount of the transmitter’s energy at any point along the pipe or cable. View photo.

Current measurement: a receiver reading, usually displayed in milliamps, that is produced by stacked-peak antennas and estimates how much of the transmitter’s energy is located at the point of the reading. View movie.

Depth validation: the raising of the receiver a known amount to see if a new digital depth reading has increased by that known amount. View movie.

Digital depth: a pipe or cable depth estimation utilizing at least two stacked peak antennas situated a fixed distance apart.

Direct current: the type of energy produced by batteries; energy that flows in one direction.

Earth: soil.

Electronic null: a receiver response whereby two symmetrically and horizontally positioned peak antennas record identical signal strengths. View photo.

Energize: to transfer the transmitter’s energy to a pipe or cable.

Far-end: the end of a line leg opposite of the transmitter location.

Far-end ground: a pipe or cable’s metal component making contact with earth at the opposite end of a line leg from where the transmitter is deployed.

Frequency: the transmitter’s energy as measured in hertz or kilohertz. View movie.

Ground rod: a copper or aluminum rod ranging in length up to 16 feet that serves to ground a cable system. View movie.

Inductive coupler: a type of inductive transmitting antenna that is not located in the transmitter but rather in the clamp that encompasses a cable. View movie.

Isolate: the ability to keep the transmitter’s energy away from non-target lines. View movie.

Logical or visual termination point: a trace that leads to an above-ground, utility-related structure. View movie.

Low-high frequency: any transmitting frequency less than 200 kilohertz but greater than 10 kilohertz. View movie.

Nonmetal-to-metal: another term for the use of an inductive transmitting antenna. View movie.

Non-target line: any pipe or cable not intended to be detected.

Not-round field: a magnetic field that is either an attracting or repelling field. View photo.

Null: a receiver response taken at the apex whereby the coil orientation is horizontal, like a tornado. View movie.

Passive: a receiver response to a magnetic field generated by something other than the transmitter. View movie.

Peak: a receiver response taken at the apex whereby the coil orientation is vertical, like a tornado. View movie.

Perpendicular conductor: a conductor that has no chance of being induced. View photo.

Pumpkin-shaped field: the field that is produced by an inductive transmitting antenna. View photo.

Radio frequency: another name for high frequency.

Receiver: a handheld antenna or series of antennas used to determine the strength and location of a magnetic field.

Receiver reading: signal strength, a peak or a null response, a digital depth reading or a current measurement.

Receiving antenna: a symmetric metallic winding induced upon by a magnetic field. View photo.

Resistance: anything that reduces current flow.

Round field: a magnetic field that is not an attracting or repelling field.

Signal: the part of a magnetic field that intersects a receiving antenna.

Signal circle: the transmitter’s energy that orbits the pipe or cable at a particular distance from the pipe or cable.

Signal decay rate: the diminishing strength of the magnetic field as the field travels away from the pipe or cable.

Signal shape: a magnetic field that is either a round or not-round.

Signal splits: a location along the pipe or cable where the transmitter’s energy can begin to travel on two or more new line legs.

Signal strength: measurement of the magnetic field with a tire coil orientation.

Single antenna receiver: a receiver that only employs one antenna.

Single frequency transmitter: a transmitter which generates only a single frequency.

Splice: a potential signal split on a cable system where the transmitter’s energy encounters multiple new line legs and the potential of going to earth.

Stacked-peak antennas: two coils—a bottom receiving antenna and a top receiving antenna—which are both situated at the apex of two concentric signal circles.

Target line: the pipe or cable intended to be detected.

Tee: a potential signal split on a piping system where the transmitter’s energy encounters two new line legs.

The path of least resistance: the metallic path which provides the transmitter’s energy the greatest opportunity to return to the transmitter.

Tire: a vertical coil winding that provides a peak response; windings that are orientated to the pipe or cable like a “tire to the road.” View photo.

Top receiving antenna: the upper half of stacked-peak antennas. View photo.

Tornado: a horizontal coil winding that provides a null response; windings that are orientated to the pipe or cable like a “tornado traveling down the road. View photo.

Trace: the entire section of a pipe or cable being located.

Transmitter: a generator of alternating current, or energy; a miniature power plant.

Transmitting antenna: a metallic device used to transfer the transmitter’s energy from the transmitter to the pipe or cable. View photo.

Triangulation: a method for depth determination utilizing a single null antenna or a pair of horizontally-positioned peak antennas held at a 45-degree angle. View photo.

Unarmored splice: a break in a cable’s metallic continuity. View photo.

Un-bond: the physical detachment of one line leg from other line legs or a ground.

Vertical inspection of field: receiver readings that are obtained on top of the pipe or cable location. View photo.

Voltage: the amount of pressure behind the transmitter’s energy.

Windings: the wire in a coil which is wrapped around the core.