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Copper Line Tests: Difference between revisions
→More info on Loop and resistance faults: clean up
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*'''Earth Contact fault''' The line is going to earth. The line may be damaged and wire touching earth somewhere
*'''Rectified Loop fault''' a one way loop - check internal wiring before going further.
**Some further info here: https://groups.google.com/forum/#!topic/uk.telecom/QdsxWT3QcvQ and see the notes below:
*'''High Resistance DIS fault''' Both lines have high resistance - some connection problem along the line.
If you get a Copper line test error, try the test again with all equipment unplugged, and the NTE5 faceplate removed as the fault could be caused by local wiring or equipment.
==More info on Loop and resistance faults==
Loop fault is a symmetric low DC resistance between A/B wires in the pair. Rectified loop fault is an asymmetric low DC resistance between A/B, as-if there's a diode shorting the fault.
At DC, the line should appear as an open circuit (infinite resistance).
A loop test (among other things) applies a known DC voltage to the line, and measures the current flow - it should see 0 mA current flow with phones all on hook. It then reverses the DC voltage, and expects to see 0 mA again.
If it sees current flow when it applies voltage, you have a loop fault. If the current is different depending on whether A or B is +ve relative to the other, you have a rectified loop fault.
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