Walk-In Cooler Lights Not Working or Flickering? Causes and Fixes

Dead lights in a walk-in sound minor until someone has to work in a dark, cold box with wet floors and a door that closes behind them. Lights also matter for stock rotation, spotting spills and spoiled product, and finding the inside door release.

Most lighting failures come from the same few things: power, controls, moisture and cold.

Safety: Don't work in a walk-in with the lights out. Don't go in alone: have a second person outside, use a flashlight, and make sure everyone knows where the inside release is. OSHA warns that condensation can make walk-in floors wet and slippery, and a dark box makes that worse. See inside safety release.

What's usually behind it

Moisture and vapor-proof fixtures

Walk-in fixtures are built to be vapor-proof: a sealed housing and a gasketed lens keep moisture out. Every time the door opens, warm, humid air comes in and condenses on cold surfaces. If the lens gasket is torn, a cover is cracked, or someone sprays water at the fixture during cleaning, moisture gets inside, corrodes the contacts and causes flicker, short circuits or tripped breakers. Water inside the lens is a sure sign the seal has failed.

Cold and LED drivers

LEDs themselves handle cold well, but the driver (the power supply that runs them) and any fixture electronics have temperature ratings. A fixture or lamp not rated for freezer temperatures may be slow to start, flicker or fail early. When replacing lights, choose fixtures rated for the box's temperature and for wet locations.

Switches, sensors and timers

Federal efficiency rules for walk-ins require interior lighting of at least 40 lumens per watt, or a timer or device that turns lights off within 15 minutes of the walk-in being unoccupied. Many boxes use occupancy sensors to save energy. A sensor that's blocked by shelving or aimed badly may switch lights off on someone working in a back corner. A sensor that fails may leave them off. See DOE rules and repairs for what to keep in mind when replacing lighting.

The light switch is often outside the door, sometimes with a pilot light so staff can see from outside if the light is on. A burned-out pilot or a switch left off is an easy fix.

Breakers and GFCIs

Lighting may share a circuit with other loads or be on a GFCI (ground-fault) device. Moisture in a fixture is a classic cause of GFCI trips. If a breaker or GFCI trips again after one reset, leave it off and call an electrician. See tripping breaker.

Checks staff can do safely

1. Check the switch. Is it on? Does the pilot light work?
2. Check whether all lights are out or just one. All out points to the switch, breaker, GFCI or sensor. One out points to that fixture.
3. Check the breaker and GFCI. Check positions only. A single reset is reasonable if everything is dry and there's no burning smell. If it trips again, leave it.
4. Test the sensor. Walk into the box and move around. Do the lights come on? Do they stay on while you work in the back?
5. Look at the fixtures. Water or fog inside the lens? Cracks? Missing gaskets? Note which fixture.
6. Don't open fixtures that are wet. Moisture plus line voltage is a shock risk.
7. Report it and put up a sign so no one works in the box without a flashlight and a second person.

Tip: Don't spray water or cleaner at light fixtures during cleaning. Wipe them down with the power off. See cleaning a walk-in cooler.

What an electrician will check

• Supply voltage at the fixtures, the switch and any sensor.
• The circuit, breaker and GFCI, and whether moisture is causing trips.
• Fixture seals, gaskets and covers.
• Driver and lamp ratings for the box's temperature.
• Sensor placement and time settings.
• Connections and wiring in the ceiling for corrosion or damage.

Our electrical requirements page covers circuit basics for walk-ins.

Glass door lighting

On beer caves and convenience-store coolers with glass merchandising doors, product lighting is usually built into the door frames or mullions with its own power supply. Those lights fail differently from ceiling fixtures and are covered on glass display door problems. If you're replacing old doors, our display door options page covers the brands JayComp installs.

Replacing fixtures: what to ask for

When an electrician replaces walk-in lighting, a few details save repeat failures:

• Temperature rating that covers your box, especially in a freezer.
• Wet-location, sealed construction with a gasketed lens.
• Shatter-resistant covers, so a broken lamp doesn't put glass or plastic on product or the floor.
• Efficiency and controls that meet the federal walk-in lighting rule: at least 40 lumens per watt, or a sensor or timer that turns lights off within 15 minutes of the box being empty.
• Sensor placement that sees people anywhere in the box, including behind tall shelving.
• Sealed wire entries, since conduit and cable entries are a common path for moisture.

If the box is being remodeled or the refrigeration replaced, it's a good time to upgrade lighting at the same time.

Energy note

Old lamps left on all day add electricity and add heat the refrigeration has to remove. If your lighting is old, replacing it with efficient, cold-rated fixtures on a sensor or timer is a common upgrade. See high electric bill.