Cables locators

Fig. 1.24 Guidant Reliance and Medtronic Quattro implantable cardioverter-defibrillator (ICD) leads have asymmetrical body designs, with the cables located on one side and the coiled conductor on the other. New models of St. Jude ICD leads have a concentric design (SJM Durata). In this case, the coil is in the body s central axis, equally surrounded by six protective cables (courtesy of St. Jude Medical, Boston Scientific, and Medtronic)...

In our example, cables located in the same culvert give location-specific interdepen dencies for electric supply and ICT. 

In the culvert at Oslo S there was redun dancy (marked with a black frame in Fig ure 2) in terms of an extra electric cable, (located in the same culvert). 

X by using pipe/cable locator (Note these devices do not detect plastic pipes)... 

Suspension bridge cables pass over cable saddles that are usually anchored to the top of the tower. A cable produces a large vertical force, as well as smaller, but important, transverse and longitudinal forces from temperature, wind, earthquake, or any unbalanced cable forces between the main and the side spans. These forces are transmitted through the cable-saddle anchorage at each cable location, to the top of the tower. The towers and the permanent saddle anchorages must be designed to resist these cable forces. 

Because the extra tie back system has to be installed far beyond the expected failure surface of the retaining wall, one of the practical restrictions for combined systems is the limits of available construction area. Furthermore, the combined system requires clear markers on finish grade to indicate the link rod or cable locations as prevention of possible damage from future construction. 

Excavations will be supported as appropriate. Where flooding risk exists, cofferdams/caissons will be installed with pumps of suitable capacity. Substantial barriers will be erected around excavations. Where poor ventilation is identified the atmosphere will be continually monitored. A permit to work will be used. Stop barriers will be used to prevent vehicle entry. Spoil and materials will be stacked at least 1.5 m from the edge of excavations. Ladders will be provided for safe access/egress. Cable location devices and local authority drawings will be used to trace buried services prior to commencement of work. Suitable signs and barriers will be provided to warn of the work. 

Supervisors must have received training in COSHH appreciation, general site safety, theory and practice of excavation work. Operatives must have received training in excavation support procedures and use of cable location devices. This applies to sub-contractors as well as direct employees. 

Have underground electricity cables been located (with a cable locator and cable plans), marked, and precautions for safe digging been taken ... 

The position of the buried cables shown on the location drawings should be checked with a cable location tester. 

There is a variety of cable locators readily available, varying in sophistication but of three generic types ... 

Cable locators should be used only by personnel trained in their use. It is good practice to use them from time to time as the excavation work proceeds until the cable is exposed. Quite often, and particularly in urban areas, there may be more than one cable laid at the same or different depths. Care in the use of the cable plans and locators is needed to ensure that the location of all the cables is determined and that cables located in close proximity to other cables, including above other cables, are properly resolved. Cables are not always distinguishable by sight from other services, but the use of a locator should enable the operator to be sure. 

A safe system of work is required to avoid the sudden discovery of services which, if interrupted, could be dangerous to the excavation worker and to those supplied by the service. Safe digging practices include hand-digging where necessary, rather than relying on fine movements of an excavator bucket arm. Cable locators should always be used to augment information from plans, which is often relatively inaccurate. 

Supervisory staff should be trained in the operation of cable locating equipment, and contents of HSG 47. Operatives locating services must be similarly trained. 

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