Short answer
Single fixtures that flicker, buzz or glow dim usually have failing lamps or ballasts, especially in older fluorescent fixtures. When a whole bank of lights goes out together, look at the circuit, a lighting contactor, or a time clock or control instead. Often the best long-term fix is an LED retrofit, and rebates may be available. Select Electric does ballast and lamp replacement and energy-efficient lighting upgrades, and is a Consumers Energy Trade Ally.
What's Probably Happening
Commercial lighting fails in patterns. Whether it's one fixture, a scattering of fixtures, or an entire zone at once tells you where to look.
Worn-Out Fluorescent Lamps
Fluorescent tubes dim, flicker and darken at the ends as they age. A single dead or flickering tube in an otherwise working fixture is often just the lamp. In spaces that rarely get relamped, many tubes reach end of life around the same time.
Failing Ballasts
The ballast regulates current to the tubes. As it fails, fixtures hum or buzz, flicker, start slowly, glow dim, or go dark even with new lamps. Older magnetic ballasts can also run hot and give off a distinct smell. Cold spaces, like unheated warehouses in a Michigan January, make weak ballasts and lamps even harder to start.
Mixed Parts and LED Tube Problems
Plug-and-play LED tubes depend on a compatible, working ballast. When that ballast fails, the LED tube goes dark too. Mixing tube types or ballast types within a building makes troubleshooting harder. Ballast-bypass tubes avoid the ballast entirely but require the fixture to be rewired for line voltage.
A Bank of Lights Out: Circuit, Contactor or Controls
When a row or zone goes dark all at once, the cause is usually upstream of the fixtures: a tripped breaker, a failed lighting contactor, a time clock that lost its schedule after a power outage, an occupancy sensor or a control panel. Lights that come on at the wrong times point the same direction.
Loose Connections
Vibration from equipment and doors in shops and warehouses can loosen connections in fixtures and junction boxes, causing intermittent flicker across several fixtures on the same run.
What You Can Safely Check Yourself
- Note which fixtures are affected: one, several scattered, or a whole row or zone.
- Check whether the problem started after a power outage or storm. Time clocks and controls may need resetting.
- Check the panel for a tripped breaker on the lighting circuit, and reset it once without opening the panel cover.
- Note what kind of lamps are in the fixtures: fluorescent tubes, plug-and-play LED tubes, or integrated LED fixtures. Check for labels inside the fixture if you can see them without opening anything.
- Only relamp a fixture if it's safe to reach, the lighting is switched off, and you're using the correct lamp type. Leave ballast work to an electrician.
When to Stop and Call
- Fixtures still flicker or stay dark with new lamps.
- A fixture hums loudly, smells hot, or shows browning or smoke. If there is smoke or flame, evacuate and call 911.
- A whole bank or zone is out, or lights run on the wrong schedule.
- You're spending more time relamping than you'd like and want to look at an LED retrofit.
- You want to convert fluorescent fixtures to ballast-bypass LED tubes. That rewiring is electrician work.
Select Electric has served commercial and light industrial customers in Midland, Bay and Saginaw Counties since 1983, with ballast and lamp replacement, electrical maintenance, and energy-efficient lighting upgrades. As a Consumers Energy Trade Ally, we can help you see whether rebates may be available for a retrofit. Call (989) 835-3587 and tell us what's out and what kind of fixtures you have.
Common Questions
Should I replace the tube or the ballast?
If one tube is dark or blackened at the ends and the others in the fixture are fine, a new tube may be all it needs. If new tubes flicker or stay dark, or the fixture hums or smells, the ballast is likely failing. When several fixtures are aging at once, an LED retrofit often makes more sense than a round of new ballasts.
What's the difference between plug-and-play and ballast-bypass LED tubes?
Plug-and-play LED tubes run on the existing fluorescent ballast, so installation is quick, but the ballast can still fail later and take the tube down with it. Ballast-bypass tubes are wired directly to line voltage with the ballast removed, which eliminates that failure point but requires rewiring the fixture and labeling it. The rewiring should be done by an electrician.
A whole bank of lights went out at once. Is that the ballasts?
Probably not. Many fixtures failing at the same moment usually points to a tripped breaker, a lighting contactor, a time clock or control, or a wiring problem on that circuit. That's a troubleshooting call.
Are there rebates for LED lighting upgrades?
Rebates may be available through Consumers Energy's business programs for qualifying upgrades. Select Electric is a Consumers Energy Trade Ally and can help you see what applies to your project. Amounts and eligibility depend on the program and the equipment.