EZiCAT Cable Locators – This Is How They Work
Undertaking any excavation will inevitably bring site workers into close proximity to underground utilities (electricity, gas, telecommunications, water). It is really important to know the exact location of all buried utilities before and during the excavation process.
To safeguard against utility strikes, a cable locator is used for detecting the presence and proximity of buried utilities.
The GeoMax EZiCAT cable locators use aerials built up of wire. This wire is wrapped around ferrite rods to detect the magnetic field emitted from a buried utility. These aerials amplify the small electromagnetic signal released by electricity / telecommunication / gas / water pipes and provides an input to the locator’s circuitry.
In order to use any cable locator on site, the buried utilities must have a passive / active location present.
Passive Location
Some electromagnetic signals are already present on buried utilities. These signals can be detected using a cable locator only
Power Mode locates electromagnetic currents radiated by energised cables which pose the most significant to excavation teams
Auto Mode, automatically locates power or radio signals, helping to confirm the presence of services upon initial site occupation making cable detection easier and safer
Radio Mode traces signals originating from distant radio transmitters. These signals penetrate the ground and are reradiated by buried conductive services
Active Location
This is where there is no signal present in the utility and we must induce a current using a signal transmitter. These signals are induced using a frequency of 8kHz, 33kHz, 512Hz & 640Hz.
8 kHz for medium-range tracing and reduced coupling to other services.
33kHZ for general standard tracing frequency on avoidance locators, used for everyday utility location
512 Hz for long-distance tracing and reduced coupling to other services. Generally used in Countries where the mains electrical frequency is 60 Hz.
640 Hz for long-distance tracing and reduced coupling to other services. Generally, we use this in New Zealand as our main electrical frequency is 50 Hz.
The above diagram displays the range of use, figures are based on the EziCat I500 and T100 transmitter connected to a 300mm (12inch) iron pipe buried at approx: 1.75m (5ft 8 inches) – 2m (6ft 6inches)
How to induce a current using a signal transmitter:
Induction Mode
Induction is a quick and simple way to apply a signal to a utility without the need to make any physical connection. An internal aerial generates a magnetic field into the ground. Any buried metallic utilities routed within close proximity to the signal transmitter will be induced with the signal, allowing the utility to be located and traced with a cable locator.
Direct Connection Mode
This is the most efficient way of applying a signal to a utility and should be used whenever possible (especially when taking a depth reading). The output from the signal transmitter can be directly connected to a cable or pipe. A circuit is completed by a connection to an earth stake or ground connection point. Applying a signal directly to the utility allows the operator to positively identify and trace its path.
