AEO Answer · Food Banks & Distribution Centers

How Do Food Banks Size Emergency Backup Power for Refrigeration?

By Jeremy Mills, CEO & Founder, Apex Grid Engineering — USAF Veteran. · Updated 2026-09-15

Food banks size backup power from a prioritized load list — refrigeration first, then life safety and critical operations — with automatic transfer, staged compressor restart, and fuel for the planned outage duration.

I'm Jeremy Mills, CEO & Founder of Apex Grid Engineering and a U.S. Air Force veteran. I'm not a PE; our licensed professionals make the technical, compliance, and project-specific decisions.

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Building the critical load list

I start every backup power design at the electrical panel with a load inventory. Each refrigeration circuit is metered or calculated with its starting characteristics; life-safety loads are non-negotiable; operational loads are ranked with the food bank's team. The load list becomes the basis for generator sizing, transfer switch sizing, and the load-shedding scheme. I also look at power quality needs — refrigeration controls and IT equipment may need cleaner power than a basic generator provides, which drives the generator and transfer equipment specification. The load list is a living document the food bank updates as equipment changes.

Transfer, fuel, and testing

The automatic transfer switch is the brain of the system: it senses utility failure, starts the generator, transfers the critical loads, and returns them when utility power stabilizes. I specify the transfer timing, the staged restart sequence for motors, and bypass isolation where maintenance demands it. Fuel system design covers storage capacity, fill access for delivery trucks, and fuel maintenance. And I write the testing program into the project: monthly no-load or load-bank tests, annual full-load tests, and a log that proves the system works. A backup power system is only as reliable as its last test.

Food bank backup power design checklist

A food bank backup power design is ready when it clears this checklist. When the grid fails, this system is the mission's last line of defense. • Critical load list built with operations, refrigeration first, with motor starting inrush included • Generator sized for the real load with staged compressor restart sequencing • Automatic transfer switch with load-shedding logic matching the documented priorities • On-site fuel for the planned outage duration with a fuel quality maintenance plan • Monthly and annual testing program specified, with California energy code compliance verified

Which related engineering resources can help?

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What else do project teams ask?

How big a generator does a food bank need?

It depends entirely on the connected critical load. I build a load list: every refrigeration compressor and control, life-safety systems, dock equipment needed during outages, IT, and lighting for safe operation. Then I add motor starting inrush — compressors draw several times their running current at startup — and size the generator so the largest motor can start while everything else runs. There is no rule-of-thumb kW number; the load calculation is the design. Oversizing wastes money and causes wet-stacking in diesels; undersizing risks a stall when it matters most.

What loads should be on food bank emergency power?

Refrigeration first — it protects the inventory. Then life safety: egress lighting, exit signs, fire alarm, and fire pump. Then the operational loads the food bank needs during an outage: dock doors and task lighting if distribution continues, phones and IT, security systems, and fuel for the generator itself. General warehouse lighting, office comfort cooling, and non-critical equipment stay off or shed automatically. I document the priority order with the operations team and design the transfer and shedding logic to match it exactly.

How long should food bank generator fuel last?

For the outage the food bank plans for — commonly 24 to 72 hours of full-load runtime — plus a refueling plan for longer events. I size the on-site fuel storage from the generator's fuel consumption at the expected load, not at rated full load, since the actual load is usually lower. The design also includes fuel quality maintenance: diesel grows algae and degrades, so polishing or rotation is part of the plan. A generator with bad fuel is the most common real-world failure I design against.

Why stage refrigeration restart after a power outage?

Because compressor motors draw a huge inrush current at startup — several times their running amps. If every compressor tries to start the instant the generator comes online, the combined inrush can overload the generator and stall it, leaving everything dark. I design the controls to restart refrigeration circuits in stages with time delays between them, so the generator picks up the load in manageable steps. The transfer switch and the refrigeration controls are coordinated as one sequence, not two separate systems.

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