Contents
Australia maintains a ‘Dial before you dig’ line, essentially a free referral service that provides information on the location of underground service lines, like water and gas pipes as well as power, telephony, and communications cables. Information is provided by line and asset owners and is available for excavators, builders, farmers, developers, and homeowners. The aim is to prevent damage to utilities and main lines and avoid any expensive repairs and delays or disruption to services. In addition, it keeps certified utility locators and anyone needing the precise location of underground utilities safe.
Potentially dangerous and expensive mistakes are sidestepped with the use of proper equipment. If you’re undertaking extensive excavation work, for instance installing an underground pool, then you’ll need a cable and pipe locator to identify all the cables and pipes that run through the property and their exact location, direction, and depth. The position of cables and piping, once located, and in or near the proposed work area, should be clearly marked before any work commences.
What are Cable Locators?
Cable and pipe locators are specialised tools used in locating underground utilities. This can be electrical cables, telecommunications and data cables (NBN and Telstra landlines), water and sewer pipelines, and gas pipes. The purpose of the cable locator for sale is to prevent any damage to existing utilities during excavation work or possible injury to workers.
Locators can be used on existing sites, like residential homes, on housing and industrial sites that have yet to be developed, as well as on larger acreage.
How Cable Locators Work
There are two basic ways in which locators detect utilities. For cables, electromagnetic detection is a simple and quick technique that will detect where power and communications lines are and whether the lines are operational or have damage (such as breaks or faults). This is done by picking up the electromagnetic field that conductors produce when energised. The majority of cable locators can distinguish between different types of cabling based on current and resistance readings in received signals. The same technique can be used for locating metallic piping.
For determining the location of non-metallic utilities, such as plastic piping for potable water, ground penetrating radar is used instead. Here, radar emits a series of radio pulses into the ground, and any objects within their path rebound an echo.
The two methods can be used together in locating cabling and pipes in more difficult areas and for more precise results.
Active Detection
Electromagnetic location can be active or passive. Active detection involves charging the target cable with electricity and using a receiver to pick up the generated signal, once that cable is energised. This can be done in three different ways.
Direct or conductive location implies a direct connection with the target cable at one end, while the other end is grounded to complete the circuit. Most locators used today have multiple frequencies. Better and more precise results are achieved using lower frequencies, due to lower leakage and interference with other metallic objects nearby. Frequencies under 1KHz are used for singling out target cables from other cabling and wires as these can also travel further and deeper. They do however have trouble in broken lines or mineralised soils. Medium frequencies are preferred in most cases where shorter cable routing is supposed and at typical depths of around 500mm. Higher frequencies are used in difficult soils and cables emitting weaker signals due to thicker sheathing or line faults.
Inductive clamping involves the use of clamps that are placed around cables with easy access, like those from utility poles or around buildings. These too need to be grounded to ensure better signal reception.
Inductive locating is done with the help of a transmitter and is helpful when there is no possibility of a direct connection. The transmitter induces an electromagnetic signal at a specified frequency in the target cable and this is picked up by the receiver. The downside to this method is the weaker signals compared to the two other active methods and the need for ideal placement of the transmitter. In addition, there is a greater chance of interference from other cables in the vicinity, making detection more difficult.
All active detecting techniques can also be used for locating metal pipes.
Passive Location
Passive locating is used in already-energised power lines and hence can be done with a receiver only. The downside is that any breaks or faults cannot be traced, as well as lines that aren’t powered during specific times, like streetlights during daytime. In addition, the strength of the signal depends on the strength of the current passing through the cable. Most detection though beings with passive location (and passive locating modes on locators that can switch between both) to get a general idea of where cables are. Then more precise location and cable mapping is done by reverting to an active cable locator.
What to Look for in Cable Locators
If you’re looking for a cable locator for sale, then depth precision, frequencies and frequency ranges, smart features, weight, and overall build are often the factors that determine the price. Locators that can detect utility lines up to 5m down will also provide more precise locating at depths nearer the surface and better target distinction in more congested areas.
Having the choice of multiple frequencies also helps precision. And speeds up detecting. Go for locators that have multiple over single frequencies. Most cable locators sold today have a dozen active frequencies and several passive frequencies.
Features like legible LCD screens, rechargeable batteries, depth indicators, cable current direction, digital signal processing (for better accuracy and less interference), and alerts for excessive sway or potentially dangerous locates, are just some of the goodies found on the many types of locators sold. For precise mapping of your finds, go with GPS-equipped locators. And Bluetooth connectivity for beaming data to mobile devices.
Lastly, consider weight, durability, and portability. If you’re a working pro and use a locator daily, then you’ll want a unit that is also light, easy to use and handle, and can operate without issue in a range of conditions.
