S2.OP-SO.125-0004 — 125VDC Ground Detection
⚠️ DRAFT — Reconstructed from exam materials
Purpose
Provides guidance for detecting and isolating grounds on the 125VDC electrical distribution system on Salem Unit 2.
Key Information
Ground Detection Criteria
| Indication | Meaning |
|---|---|
| Resistance ≤ 50K ohms | Ground IS detected |
| Resistance > 50K ohms | Normal — no ground present |
Isolation Method
- Open breakers on the bus ONE AT A TIME
- Evaluate ground readings after each breaker is opened
- Leave breaker open if ground clears (resistance rises above 50K ohms)
Exam — 2023 Q46
A 125VDC bus ground ohmmeter reading of 40K ohms indicates a ground IS detected (less than 50K ohms threshold). Per S2.OP-SO.125-0004, breakers are opened one at a time until resistance indicates greater than 50K ohms.
Connections
- Related systems: DC Power
- Related exam questions: 2023 Q46
- Related exam: 2023 NRC Written Exam