Fire Pump Controllers: ATS, Jockey Sequencing, and NFPA 20 Rules

The fire pump matters — but the controller matters just as much. Wrong sequencing leads to unnecessary pump runs, pressure hunting, or no start at all during a fire. NFPA 20 Chapter 10 defines controller requirements in detail. Here's the typical architecture of electric, diesel, and jockey controllers from a field perspective.

Three Controller Types

• Electric Fire Pump Controller: Starts electric main pump, integrates ATS for generator.
• Diesel Fire Pump Controller: Cranks diesel engine, manages two battery banks.
• Jockey Pump Controller: Auto start/stop for jockey.

Pressure Sensing

Controllers monitor system pressure via pressure sensor or pressure switch. NFPA 20 requires:

• Adjustable start/stop setpoints
• Dual redundant sensing (new installs)
• Pressure logging (last 24 hours)

Start Sequence

Typical staged start:

1. Pressure normal: system idle, pumps standby.
2. 10 psi drop: jockey starts, handles small leak.
3. Another 15 psi drop (25 psi total): main pump starts.
4. Electric first; if it fails, ATS switches to diesel.
5. Stop: main pump manual only (NFPA 20 post-2019).

ATS (Automatic Transfer Switch)

On electric pumps, ATS auto-transfers between two sources:

• Utility (grid) - primary
• Generator or alternate utility - secondary

Transfer ≤ 10 s. Fire pump ATS must be separate from the building ATS (dedicated authority).

Monitoring Signals

Controller sends to the fire alarm panel:

• Pump running (run)
• Pump fail (alarm)
• Power loss (supervisory)
• Controller switch in manual (supervisory)
• Phase reversal (electric only)

Diesel-Specific Rules

• Two battery banks; test one and it should alarm.
• Fuel level: under 67% = supervisory alarm.
• Weekly auto 10-min run test.
• Engine coolant temperature monitoring.

Common Issues (Turkey)

1. Jockey runs constantly: System leak ignored; jockey burns out.
2. Main pump auto-stop: Old NFPA 20 allowed it; new version requires manual.
3. No ATS test: Without weekly test, pump won't start in first outage.
4. Phase reversal bypassed: Some sites disable the alarm; wrong phase spins pump backwards.

Conclusion

The controller is as critical as the pump. Mechanicals right, electronics wrong → no run on first fire. NFPA 20 Chapter 10 rules on start-stop, ATS, and monitoring are minimums; don't skip them in design.

Pump controller schedule in MEP Calc

Weekly test calendar, ATS check, alarm setpoints, and log book.

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