After a power cut: the order to check things in

While the power is out

Every door opening spends a measurable part of the cold budget, and that budget is all you have. The published figures are worth memorizing because every later decision rests on them: about four hours for an unopened refrigerator, about forty-eight for a full freezer and about twenty-four for one half full. The freezer holds so much longer for a reason that has nothing to do with anything running: it starts far colder, and the frozen mass inside it has to absorb a great deal of heat before any of it begins to thaw. What dual refrigeration changes is the other half of it. A Sub-Zero built-in cools each compartment on its own sealed system with no air passing between them, so the two sides warm on entirely separate schedules and a refrigerator that has gone warm tells you nothing about the freezer beside it. If the outage will run long, move freezer contents into a cooler in one trip rather than opening the cabinet repeatedly, and keep the emergency measures outdoors where they belong.

• A packed freezer holds longer than an empty one, so fill the space with sealed containers of water
• Two appliance thermometers, one per compartment, are the cheapest insurance in the kitchen
• Never run a generator indoors or in an attached garage
• Never use a cooktop, rangetop or oven to heat a room

When the power comes back: the order

Work outward from the supply and inward toward the machine, because most built-ins that appear dead after an outage are dead for a reason that has nothing to do with the appliance. Confirm the appliance's own circuit has power instead of letting the kitchen lights speak for it, since built-in refrigeration normally sits on a dedicated circuit. Check the breaker properly, because a tripped breaker often does not look tripped: push it firmly to off, then back on. Look for a protected receptacle, whose reset may sit in another room or the garage. Only once the supply is proved does anything the appliance is doing count as evidence, and even then it deserves time before a verdict.

• Confirm power at the appliance's own circuit, not just at the room lights
• Cycle the breaker fully off and back on rather than trusting how it looks
• On a built-in the outlet is often in an adjacent cabinet or above the unit, not behind it
• Read the display, acknowledge any stored alarm, and note the peak temperature the control recorded
• Then leave it alone for several hours before deciding whether it is cooling

Why it sits silent, and when silence is a fault

A compressor cannot restart against a system that has not equalized. When the machine stops mid-cycle the high side stays under pressure for a few minutes, and a motor asked to start against that head pressure stalls and trips its overload. Controls impose a delay for exactly this reason, so a built-in that stays quiet for several minutes after power returns is behaving correctly. The interior light and display come back at once; the machine room does not. Give it ten minutes, then listen at the grille. A click every few minutes with no run following it is a compressor being stopped by its overload, which points at the start device before it points at the compressor.

• Several minutes of silence after power returns is designed behavior, not a fault
• A repeating click with no run points at the start device or overload first
• A dark display with total silence means the supply, not the machine
• Two sealed systems restart independently, so a cold freezer proves nothing about the fresh-food side

The food question is settled by temperature, not by smell

This is where the thermometer earns its place. Forty degrees Fahrenheit is the line, and perishable food held above it for more than two hours is not worth the risk however it looks or smells, because the organisms that make people ill do not announce themselves. Frozen food is more forgiving than people assume: anything still carrying ice crystals, or sitting at forty degrees or below, can be refrozen, and what suffers is texture rather than safety. Whole categories of food come through the interruption without any of this arithmetic at all.

• Perishables above 40 degrees for more than two hours are discarded
• Freezer food still carrying ice crystals, or at 40 degrees or below, can be refrozen with some loss of texture
• Hard cheese, butter, jams, most opened condiments and whole raw vegetables generally survive
• Opened mayonnaise, tartar sauce and horseradish are the exception among the condiments, and are discarded after eight hours above 50 degrees
• Meat, poultry, seafood, milk, soft cheese, cut fruit and cooked leftovers do not survive it
• Never taste to decide, and do not rely on smell

What actually breaks, and why a sagging supply is worse

Rarely the compressor itself, at least not on the day. The usual casualty is the start device or its overload, a modest part and a short visit. Next is the control or interface board, damaged by the surge that arrives when the utility re-energizes the circuit, which is often a harder electrical event than the outage before it. The real destroyer is voltage that drops and recovers repeatedly: a motor asked to start on low voltage draws locked-rotor current, never comes up to speed, and takes that punishment every time the overload resets it. If the lights are dimming and brightening during a storm, switching the refrigerator off at its breaker until the supply steadies is the right call.

• Start relay and overload: the usual casualty, and an inexpensive one
• Control and interface boards: surge damage on restoration, often visible as a scorched trace or swollen capacitor
• A compressor stressed by repeated restart attempts can run fine for two weeks and then fail
• Whole-panel surge protection is the appropriate approach for a dedicated-circuit appliance
• No plug strips and no extension cords on refrigeration

Ice, water, and the cooking appliances

Empty the ice bin completely, because ice that melted and refroze fuses into a slab and jams the mechanism as the first thing it does. The ice maker will not resume until the freezer is genuinely back at temperature, and the first harvest after that can be hours away, so give it a full day. If the water supply was interrupted too, expect air and stirred sediment down the line. On the cooking side, a gas range with electronic ignition will not light itself without power. Surface burners on many gas models can be lit by hand, and the order is not optional: the flame goes to the burner first and the knob is turned on only once it is there, never the other way around, and if it does not light within a few seconds the knob goes off and the room airs out before trying again. That is not universal, so the owner's manual is the authority for your model. A gas oven with an electronic control and a glow-bar igniter cannot be improvised into working and should not be lit by hand at all.

• Dump the whole bin rather than picking through it, and allow a full day for production to restart
• Run several gallons through a tap before expecting clean ice, and treat the filter as older than its date
• Set the clock after power returns, since many controls will not accept a cycle until it is set
• An interrupted self-clean can hold the oven door latched until the control finishes its cool-down