Generator Transfer Checklist: The Standby Generator That Starts, Then Doesn't Carry the Load

A generator's job is not to start — it is to carry the load, and those are two different failures.

Most businesses that own a standby generator have watched it pass its weekly self-test beautifully while the building stayed on wall power the whole time, because the transfer switch never moved. That is exactly what happened to a small grocery whose 14 kW unit passed every weekly self-test for two years — its ATS control board had been dead since 2024, and nobody noticed until a forty-five-minute storm outage left the store dark and the POS down.

Read the full Generator Transfer Checklist on ops-notes — here are the core moves:

1. The monthly transfer test (ten minutes, real load)

Once a month — not the weekly self-test — run four checks and log them:

1. Trigger a real transfer. Press the ATS test button. Engine starts AND the building audibly moves to generator. If the engine starts and the lights don't change, the transfer switch is the failure — the part nobody thinks to check.
2. Read the load. Sweet spot under real outage is 50–80%. A generator loafing at 5% never exercises the alternator.
3. Hold it. Fifteen to thirty minutes on generator. This is when stale fuel, a weak battery, and the low-oil cutoff show up — in sunlight, not at 3 am.
4. Transfer back. Verify the ATS moves the building to utility and the engine cools down and shuts off.

2. The load order (don't let the first inrush kill the run)

Motors draw 3–6x running current at startup. Order matters:

• First: IT, POS, refrigeration — small, steady, the things that corrupt or spoil.
• Second: lighting and pumps.
• Last / shed-able: HVAC compressors — a standby A/C compressor can double the generator size you need.

3. Fuel is maintenance, not a purchase

• Gasoline: stale in 3–6 months — stabilizer + rotation.
• Diesel: algae grows in a tank that breathes — annual tank look + additive.
• Propane: doesn't go stale, but runs out — check the gauge with every transfer test, and know your refill vendor's storm-day queue.

The four traps

• Self-test theatre: the weekly exercise proves the engine, never the transfer switch.
• The never-loaded generator: idle at 5% weekly = wet-stacking and carbon fouling while "passing."
• The HVAC inrush: one compressor startup that trips the whole unit exactly when it matters.
• Fuel that is a rumour: a working generator with stale fuel is a fifteen-minute machine.

The fix for the grocery cost one control board and a clipboard habit: the monthly transfer test, logged next to the walk-in temperature log. The next storm took power out for three hours; the store ran at 60% load the whole time, till and freezer aisle included.

Full checklist, worked example, and the traps: Generator Transfer Checklist — free, no signup. Companion page: the UPS runtime checklist covers the minutes before the generator is even up.

Free tools: The First 30 Minutes (free incident quick-start) · Ops Starter Kit ($14)