Power Generation & Distribution · SOP

Mobile Generator Setup Grounding And Load Testing

This procedure defines the required steps to safely deploy a mobile generator, establish a compliant grounding electrode system, and perform a resistive load bank test to verify output capacity and stability before connecting critical loads.

Estimated Time

90 min

Difficulty

Advanced

Regulation

CSA C22.1 / NFPA 110

Version

1.0

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Purpose

To establish a standardized, safe, and repeatable procedure for positioning, grounding, and load‑testing a mobile (trailer‑mounted) generator prior to field deployment. Proper grounding ensures operator safety and equipment protection against ground faults. Load testing verifies the generator can sustain rated output under resistive load for the required duration, avoiding nuisance trips or failure during an actual power outage.

Scope

This SOP applies to all mobile diesel/natural gas generators rated 20 kW to 500 kW owned or operated by the maintenance department. It covers outdoor setup at a temporary work site, fixed installation yard, or emergency standby location. Not applicable to portable inverter generators less than 10 kW or permanently installed standby units. All personnel performing this task must hold a valid generator operation certificate and have completed confined space and electrical safety training. The procedure assumes the generator has been serviced within the last 90 days.

Safety Precautions

LOTOLockout/Tagout the generator’s battery disconnect switch and any shore‑power or transfer‑switch connection before performing any wiring work. Verify zero voltage at output terminals using a rated voltmeter.
PPEWear Class 0 rubber insulating gloves with leather protectors, arc‑rated clothing (minimum CAT II), safety glasses, and steel‑toe boots when handling generator cables or grounding conductors. Hearing protection required during engine operation.
FUELDo not refuel the generator while the engine is running or hot. Keep a 10‑lb ABC fire extinguisher within 10 metres. No smoking or open flames within 15 metres of the fuel tank.
EXHAPosition generator so exhaust discharges away from buildings, air intakes, and personnel. Carbon monoxide detectors must be active in any occupied structure connected to the generator circuit.
LIFTUse mechanical aids (tractor, crane, or forklift) for lifting generator cables or load banks over 25 kg. No manual lifting of copper grounding rods or cable reels.

Required Tools & Materials

Grounding system: Copper‑clad steel rod (2.4 m × 19 mm), ground clamp, #6 AWG bare copper wire, split‑bolt connectors
Electrical tools: Digital multimeter (CAT III), clamp‑on ammeter, phase rotation meter, frequency meter (or combined power analyzer), torque wrench (Nm range per lug spec)
Load bank: Resistive load bank rated for at least 110% of generator kW rating; 60 Hz compatible; remote control panel
Cables: SOOW or type W power cable rated for generator current; cam‑lock or pin‑and‑sleeve connectors; cable ramps for pedestrian crossing
PPE & safety: as listed in Safety Precautions; lockout kit; confined space rescue equipment if enclosure is entered
Documentation: Manufacturer’s operator manual, load test data sheet, grounding inspection checklist

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Procedure: Step-by-Step

1 Pre‑operation inspection — Check fuel level (minimum 75% for test), engine oil (full mark), coolant level, battery voltage (12.6 V+ for 12 V systems), air filter condition, and belt tension. Inspect all cables for cuts, abrasions, or corrosion. Verify all panels and guards are in place. Record data on Generator Pre‑Run Checklist.

2 Site preparation — Select a level, dry surface capable of supporting the trailer weight (check with load‑out weights). Ensure a minimum 5 m clearance on all sides from buildings, windows, HVAC intakes, and combustible materials. Orient the exhaust away from prevailing wind direction toward occupied zones.

3 Install grounding electrode — Using a sledge hammer or mechanical driver, drive the copper rod vertically at least 2.4 m into the earth, leaving 75 mm above ground. Clean the rod surface and attach the ground clamp. Route #6 AWG bare copper wire from the generator’s designated ground lug to the clamp; tighten the connection to 30 Nm (verify per clamp spec). Test ground resistance with a fall‑of‑potential meter — must be ≤ 25 Ω. If higher, drive a second rod spaced 3 m apart and bond both.

4 Connect load cables — Identify generator output terminals (3‑phase or single‑phase per unit). Use phase rotation meter to verify A‑B‑C sequence matches load bank cable labels. Attach load cables using torque values from the generator’s connection diagram (typical: 35–50 Nm for M10 bolts). Secure cables with strain relief. Connect load bank control wiring (remote start, emergency stop) according to load bank manual.

5 No‑load start and electrical checks — Disconnect load bank breakers. Ensure generator main breaker is OFF. Start the engine per manufacturer’s cold‑start procedure. Let it run at rated RPM for 5 minutes to stabilize. Close the main breaker. Measure voltage (L‑L: 208 V, 240 V, or 480 V ±5%), frequency (60 Hz ±1 Hz), and L‑N voltage. Document readings. Check for abnormal vibrations or fluid leaks.

6 Load bank application — Energize the load bank control and apply 25% load for 5 minutes. Monitor voltage drop (should not exceed 10% of no‑load voltage) and frequency dip (max 3 Hz). Increase to 50% for 10 minutes, then 75% for 10 minutes, finally 100% for 30 minutes. Record voltage, current per phase, frequency, engine temperature, and oil pressure every 5 minutes. If any parameter exceeds the manufacturer’s limits, abort the test and investigate.

7 Cooldown and shutdown — After 30 minutes at 100%, reduce load to 0% and allow the generator to run unloaded for 5 minutes. Open the main breaker. Perform a controlled engine shutdown using the normal stop switch (not the emergency stop unless necessary). Disconnect load cables, then the ground wire, in reverse order of installation. Retract cable ramps, stow load bank, and secure unit for transport or standby. Complete the Load Test Log and flag any anomalies for corrective action.

Mobile Generator Setup Grounding And Load Testing

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