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OTDR to Real-World Distance

Find the actual ground location of a cut or damage from an OTDR reading.

OTDR Distance to Event Cable Type

Known Slack Between You and the Event

Number of Handholes / Aerial Slack Points Slack per Handhole / Point Extra Slack (buildings, risers, etc.)

Real-World Distance

Real-world distance-

Helix adjustment-

Total slack deducted-

Field TipOTDR distance is fiber length, not ground distance. Helix and slack almost always make the real-world location closer than the trace shows.

Common MistakeForgetting to subtract handhole and aerial slack. That alone can put you looking in the wrong span.

About this calculationReal-world distance ≈ (OTDR distance ÷ helix factor) − total slack.