This procedure is used to identify each end of a cable which is wrongly labeled or has no identifying tag.
INSTRUMENTATION AND EQUIPMENT
- Resistance meter (Ohms mode of a digital multimeter is sufficient)
- Abrasive cleaning implement.
- Reel of armature winding wire.
17.1.1 Draw a schematic layout of the cables and connection points, as found on site.
17.1.2 Label ALL C.P. CABLES ON SITE and their connecting points.....cable A --> connection A.... cable B --> connection B ... etc.
17.1.3 Disconnect all cables.
17.2.1 Measure and note the resistance of the complete reel of armature wire.
17.2.2 Connect the Ohm meter to the subject cable, via the armature wire, and reel it out to the suspected other end of the cable.
17.2.3 Connect the other pole of the Ohm meter to the cable.
Note The reading should be little more than the resistance of the reel of armature wire, if the two ends of the cable match.
17.3.1 When there is too much resistance, considering the length of the cable run, then try all the other, cables until a suitably low reading is obtained.
17.4.1 Label each end of the identified cable AA......AA, leaving the original labeling in place, for the time being.
17.5.1 Mark the schematic drawing with the cable and label.
17.6.1 Repeat steps 17.1.2 to 17.5.1 until all cables are accounted for.
17.6.2 Submit a schematic drawing, of the location CP wiring, to the CP archive file, with a copy placed in the cover of the TR on site.
17.6.3 Fix a schematic drawing of the CP wiring to the cover of the TR on site.
17.7.1 Label each of the junction boxes with it's identity number.(The numbers should progress,from the closest to the furthest away from the TR.)
17.8.1 Attach a schematic drawing of the inside of each junction box to the junction box cover.
17.8.2 Submit a copy of each schematic junction box drawing to the CP archive file.
NOTE It depends on the metallic path being the least resistance between the two ends of the subject cable and therefore can give misleading indications if there is an alternative low resistance path, caused by ruptured insulation to earth or metallic short-circuit. It is therefore essential that all readings are noted accurately and connections are made with care.
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