One of the main hazards that can be encountered while digging is possible injury from an underground cable. The illustrations below describe the most common circumstances leading to contact with live electrical cables. Remember that you should not begin digging until you have taken all necessary precautions.
Injuries resulting from damage to live electrical cables are usually caused by the explosive effects of arcing current and associated fire or flame.
This can occur when the cable sheath and conductor insulation are penetrated by a sharp object, such as a tool tip, or when the cable is crushed severely enough to cause contact between the sheath and one or more conductors. This usually results in severe and potentially fatal burns to the hands, face and body.
Direct electrical shock is also possible. In addition, some high voltage electrical cables are filled with oil and the oil can ignite. Electrical fires can be catastrophic if the damage spreads to other nearby services, such as gas lines.
These accidents occur because not all reasonably possible precautions have been taken to avoid accidental contact with underground services. Recommended methods and procedures are outlined in this code which, if adopted, will provide a positive approach to eliminating these tragedies.
The Basic Elements of a Safe Work System :
Correct Use of Drawings (To Help Locate Electrical Cables)
Before starting the job, it is essential that you have all the cable records for the location and that these are kept on site at all times during the course of the job.
Make sure they are up to date, cover all cable voltages on the site, that you understand how to interpret them, and that they are fully utilized before you start digging and throughout the duration of the job.
Use of Cable Locators
Appropriate cable locators should be used in conjunction with cable plans to determine as accurately as possible the position of underground cable locator in or near the proposed work area.
Use Detection Tools
This is the simplest step, but also the most important. Do not dig until the area has been scanned and marked by trained personnel using reliable locating tools. Use the tools in conjunction with maps (when they are available), but never rely on maps alone.
There are two main approaches to finding buried services with electromagnetic fault locator: avoidance and precision locating. For the avoidance approach, C.A.T tools are easy to use but powerful tools for locating buried utilities. They are designed for excavation crews to use as part of their excavation process.
For accurate locating, the 8100 Series locators are designed for use by professional utility locators and survey professionals, and offer a much wider choice of modes and frequencies for accurate identification of individual services.
Regardless of the approach taken, it is essential that the fault locator be used with suitable signal transmitters, such as Genny4 or TX-10 transmitters. The correct use of transmitters makes it easy to locate cables that would otherwise be very difficult to find.
The Risks Associated with Electrical Cables:
Underground Cable Locator
When digging or drilling, one of the main dangers is damage to underground cable locator. You can receive an electric shock or electrocution if you come in contact with live cables of any voltage, including low voltage.
Low Voltage Cables can be Deadly
Contact with cables of any voltage, even low voltage, can cause fatal injuries such as heart damage.
Explosion, Fire or Flame
If a cable is punctured or crushed and the outer sheath of the cable and the inner conductors of the cable connect, it can cause an explosion, fire or flames. You could be left with serious and potentially fatal burns to your hands, face and body.
Catastrophic Electrical Fires
High voltage electrical cables can be filled with oil and the oil can ignite. Electrical fires can be catastrophic if damage spreads to other nearby services, such as gas lines. If a gas line catches fire, it can further fuel the fire.
Why excavate tens of linear meters to find a cut electrical wire? Our technology allows us to identify the place into the ground where a wire or telecommunication copper is cut.
Fault location on communication and power cables is a very specialized area of electrical technology. The performance of efficient fault location is very much dependent on good logistics and the knowledge of the technician.
Use of Cable Plans
Prior to beginning excavation work, plans or other appropriate information concerning all buried services in the area should be obtained and reviewed.
If the excavation work is urgent and the plans or other information cannot be found, the work should be performed as if there are live buried services in the area.
Symbols on electrical cable plans may vary from utility to utility and advice should be sought from the office that issued them. Keep in mind that high voltage cables may be shown on separate drawings from low voltage cables.
Plans only give an indication of the location and number of underground services on a particular site. It is essential that a competent person trace the cables using appropriate locating devices.
Cable Locators
Before work begins, underground cables must be located, identified and clearly marked.
The position of the cable in or near the proposed work area should be located as accurately as possible using a locating device, using plans and other information as a guide to the possible location of services and to help interpret the signal.
Keep in mind that fault locator must be used frequently and repeatedly during the course of the work.
Persons using a fault locator should be thoroughly trained in its use and limitations. Locating devices should always be used in accordance with the manufacturer’s instructions, checked regularly and maintained in good working order.
Excavation Practices
Excavation work should be done with care and follow accepted safe digging practices. Once a locating device has been used to determine the position and route of the cables, excavation may proceed, with test holes dug using appropriate hand tools, if necessary, to confirm these positions.
Dig along the service rather than directly over it. Final exposure of the service by horizontal digging is recommended, as the force applied to the hand tools can be controlled more effectively. Insulated tools should be used when digging next to electrical cables.
Many of these are processes are the essential grounds for correct decisions to be made. With the use of special attachments to our underground utility locating equipment such as Ground Penetrating Radar (GPR), we can detect the approximate location of underground cable faults, opens, and other defects to electric and copper telephone systems. When approaching a cable fault, the front and back arrows will point in the direction of the fault when you use the A-frame fault locator.
The strength number of the signal indicates the approximate strength of the fault. This is used to indicate if there are multiple faults on the same cable and, if so, determine if the target fault is the major fault. Some major cable faults may be identified without the use of the A-frame, using just the digital locator. This can be determined by identifying the areas where dramatic signal change occurs.
Our professional pipe locators can also help you in finding underground utilities.
Summary
Damage to underground pipes and cables during excavation is a serious and costly problem that is growing in importance. By focusing on three key, simple steps, companies can significantly reduce the risk of damage and harm:
- Use the best cable detection tools.
- Develop excellent work procedures and ensure people are trained.
- Change behaviors on site through effective supervision and monitoring.
This will embed best practices in the company and reduce the number of utility incidents. Contact us or call us for more information.