Restaurant standby generator: walk-ins, registers and the kitchen line

A restaurant standby generator is sized around one question: what has to keep running when the power fails? For most kitchens the answer starts with the walk-ins, because a cooler that warms up overnight costs product. After that come the registers, the lights and, if you want to keep serving, the cooking line and its hood. We sell and install Generac home standby and commercial generators, and this guide covers how a restaurant's list turns into a generator size.

Does a restaurant need a standby generator?

Often a standby generator is a business decision: the cost of lost product and closed hours against the cost of the system. Where the code requires certain loads to stay on, the building's design and the authority having jurisdiction set that, and the generator is wired to the classification they decide.

The question to ask yourself is what an outage costs you now. A walk-in full of product, a weekend dinner service, a catering order due in the morning: each one is a reason to put something on the list. You choose the loads, and the size follows the list, so the generator does not have to carry the whole building.

What should a restaurant put on a standby generator?

Start with the walk-in coolers and freezers, then the reach-ins, the registers and card terminals with the network they run on, the lighting and the security system. If you want to keep cooking, add the hood, its exhaust fan and the make-up air. A retail counter's list is usually the registers, the lighting, the sign and the security.

• Walk-in condensers and evaporators, each on its own circuits.
• Reach-in coolers and freezers on the line.
• Registers, card terminals and the network equipment they depend on.
• Dining room and kitchen lighting, the sign and the security system.
• The hood, its exhaust fan and the make-up air, if the kitchen keeps cooking.

The same list applies to stores and storefronts, as our restaurant and retail standby generators page explains.

Can a standby generator run a restaurant walk-in cooler?

Yes, if the walk-in is on the load list the generator is sized for. Each walk-in has a condenser and an evaporator on their own circuits, taken from the refrigeration contractor's sheets. The load study counts how each compressor starts, because that starting surge is larger than what the compressor draws once it is running.

Two walk-ins whose compressors start at the same moment put a larger demand on the generator than either one alone. The load study accounts for that. It also checks that the condenser on the roof or the pad and the evaporator inside the box are both on the transfer switch, because a running condenser with a dead evaporator fan does not keep the box cold.

Can a restaurant keep cooking on generator power?

It can, if the cooking line's electrical loads are on the list. Gas cooking still needs the hood, its exhaust fan and the make-up air, and those motors have to be on the generator. Electric fryers, ovens and dish machines add much larger loads, and each one adds to the size and the price.

Decide this one first, because it sets the size more than anything else. A plan that keeps the walk-ins, the registers and the lights on, and closes the line during an outage, is a far smaller generator than one that keeps the full menu running. Some kitchens choose a middle path: the hood, a few pieces of gas equipment and the reach-ins on the line, with the electric fryers left off.

How is a restaurant standby generator sized?

From a load study. Every cooler, fryer and dish machine has a cut sheet naming its voltage, phase and load, and the walk-ins have the refrigeration contractor's sheets. We build the list from those sheets and from measurements at the panel, count how the compressors and motors start, and leave room for equipment you plan to add.

Send the equipment list before the walkthrough if you have it. If you do not, we read the nameplates and the panel schedule on site. Tell us about the equipment you plan to buy too, such as a second walk-in or a new line, because a generator sized only for today's kitchen can be too small after the next expansion.

The requirements that shape a commercial system are covered in our post on commercial standby generator requirements.

Which electrical code articles apply to a restaurant generator?

The National Electrical Code treats standby power three ways: emergency systems in Article 700, legally required standby in Article 701, and optional standby in Article 702. Which one your loads fall under is set by the building's design and the authority having jurisdiction, and it decides how the system is wired, separated and tested.

Walk-ins, registers and the cooking line chosen by the owner are the kind of loads that can be optional standby. Exit lighting and other life safety loads, where the building has them on emergency power, are set by the design, not by the owner's list. We explain the classification before the bid, so the price matches the wiring the code calls for.

Where can a generator go at a restaurant in a leased space?

In a leased space, the property owner or manager settles where the unit can sit before the pad goes in. Placement is also set by the setbacks and the service access the code and the manufacturer call for, so the spot has to satisfy the landlord, the code and the generator at the same time.

A natural gas unit needs a gas line sized for the generator. Gas line and gas connection are not included. That is a licensed plumber's work and we quote it separately. We coordinate the plumber with the electrical work. A diesel unit carries its own fuel tank, and the fuel vendor fills it. Either way, the walkthrough looks at where the gas meter or the tank would go, and how the truck reaches the pad.

Can a standby generator be installed without closing the restaurant?

Yes, for most of the work. Setting the pad, the unit and the feeders can happen around service. The shutdown to connect the transfer switch is the one moment the power must be off, so it is scheduled after close or before prep starts, and the switch over to the new equipment is planned with you.

Plan the shutdown around the walk-ins as well as the hours. Keeping the doors closed while the power is off, and starting the shutdown when the boxes are at their coldest, protects the product while the switch is connected. Inside San Antonio, the City's electrical permit application covers generators. Outside the city, we confirm what that city requires before we give you the price.

The full scope for a business is on our commercial standby generators page, and the residential side is on Generac generator installation.

How much does a restaurant standby generator cost?

It depends on the list. Walk-ins and registers alone make a far smaller system than a full cooking line, and the feeders, the transfer switch and the gas line change with the building. You get a written price after the free sizing visit, which for a business is a walkthrough of the building with a licensed electrician.

Request a walkthrough from our restaurant and retail generator page or through our contact page. Every Generac size and the commercial pages are on our Generac generators page, and a medical practice planning the same work can read medical office standby generator.

Once it is in, scheduled maintenance covers the generator, the batteries and the transfer switch, with written records after each visit. Our Generac generator maintenance schedule explains what a service visit includes.