This practical guide shows you how to complete a signed, QR-verified EPO (Emergency Power Off) Functional Safety Checklist certificate in OhmCert Module #24 and how to troubleshoot non-compliant readings on site.
1. Step-by-Step OhmCert UI Workflow
- Open Module #24: Navigate to EPO (Emergency Power Off) Functional Safety Checklist from the Dashboard.
- Load a 1-Click Standard Annex Preset: Open the blue Standard Annex banner at the top and click a preset (such as "24 V DC Battery-Backed EPO System (4 Exits, 180 ms Trip)") to populate target limits automatically.
- Enter Your Field Measurements: Fill in the measured inputs (Measured De-energisation Time, Number of EPO Stations, Number of Principal Exit Doors, Shunt Trip Coil Voltage, Rated Coil Voltage, Interlock Loop Resistance). Blank inputs stay neutral
PENDING. - Complete the 13-Point Checklist: Grade each item, attach photos if needed, and export the SHA-256 signed PDF certificate.
2. Worked Numerical Field Case Study
Scenario: 24 V DC Battery-Backed EPO System (4 Exits, 180 ms Trip) (NEC 645.10 / IEC 60947-2) — Data hall EPO loop with 4 principal exits and 24 V DC supervised shunt trip supply..
- Number of EPO Stations:
4 - Number of Principal Exit Doors:
4 - Measured De-energisation Time:
180 ms - Shunt Trip Coil Voltage:
24.2 V - Rated Coil Voltage:
24 V - Interlock Loop Resistance:
2.4 Ohm
3. Engineering Troubleshooting: Corrective Actions When a Reading Fails
- Install hinged, audible-alarmed protective covers over all EPO pushbuttons at exit doors.
- Replace corroded auxiliary contacts or undersized control wiring if EPO loop resistance exceeds 1.0 Ohm or coil voltage drops below 85%.
- Rewire reset logic so unlatching the EPO button only clears the lockout relay without closing upstream breakers.
→ Try This Worked Example Live in Module #24 (EPO Functional Safety)