
CableSHARK P3 User Guide
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5. For the grounded system, the CableSHARK switches the loop current path with the 435 ohm load
(currently off hook), from tip-ring to tip-ground. The CableSHARK measure both the ring-ground
voltage and the loop current.
The Ground Resistance measurement sequence is based on the following assumptions:
1. The ground lead of the instrument is connected reliably to the ground of the CO
2. The standard CO voltage is nominally -48 VDC. The twisted pair is connected to the CO with tip as
positive and ring as negative.
3. The grounded constant current source limits the current on the –48 V side only.
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