Why Are My LED Lights Flickering? Causes and Fixes in Phoenix

First question: one light, one room, or the whole house?

Where the flicker shows up tells you more than anything else. Before you buy new bulbs, spend a day noticing the pattern:

• One bulb or one fixture. Almost always the bulb, the socket or the fixture's built-in driver.
• Every light on one dimmer. Usually a dimmer and LED compatibility problem.
• Several rooms on the same circuit. Points toward a loose connection somewhere on that circuit.
• Lights all over the house, especially when big loads start. That's a service or neutral question, not a bulb question.

If the whole house dips for a moment when the air conditioner kicks on, read our post on why lights dim when the AC turns on. That's a different problem from LED flicker, and it has its own list of causes.

Cause 1: the dimmer wasn't made for LEDs

This is the most common reason for LED lights flickering on a dimmer. Many older dimmers were built for incandescent bulbs that drew 60 or 100 watts each. A room full of LEDs might draw a fraction of that, which can fall below the dimmer's minimum load. The result is flicker at low settings, a buzz from the switch, lights that won't turn fully off, or a faint glow when the switch is off.

The fix is a dimmer rated for LED loads, and bulbs marked dimmable. Dimmer makers publish compatibility lists that show which bulbs they've tested, and it's worth checking yours against the list. Many LED dimmers also have a low-end trim adjustment, which stops the flicker at the bottom of the range. Mixing bulb brands on one dimmer can cause uneven dimming too, so keep a room to one bulb model.

Cause 2: heat, which matters more in Phoenix

LEDs run cooler than old bulbs, but the electronics in the base still make heat. According to ENERGY STAR's guide on how LED bulbs work, LEDs use a heat sink to carry that heat away so they don't overheat and burn out. Put a standard LED bulb in a sealed glass fixture, a closed ceiling dome or an outdoor lantern on a west-facing wall in July, and the heat has nowhere to go.

An overheating LED often flickers, cycles off and on, or dies early. If the bulb that keeps failing lives in an enclosed fixture, look for bulbs labeled for enclosed fixtures, and for outdoor fixtures, bulbs rated for wet or damp locations. Patio and garage fixtures in the Valley see temperatures that indoor bulbs simply weren't designed for.

Cause 3: a cheap driver or integrated fixture

Many newer fixtures, including the canless wafer lights used in most remodels, have the LED and its driver built in. There's no bulb to swap. When a budget driver starts to fail, the light flickers, strobes or shuts off after a few minutes. If one fixture in a run of identical lights acts up and the others are fine, the fixture itself is the likely problem. Our post on recessed lighting installation covers what to look for when choosing fixtures that hold up.

Cause 4: smart switches and missing neutrals

Some smart switches and timers need a neutral wire in the box. Older homes, and many switch boxes in homes of any age, don't have one. Smart switches built to work without a neutral pass a tiny current through the bulbs to power themselves, and with low-wattage LEDs that can cause flicker or a dim glow when the light is off. The fix may be a different switch, a bypass device the manufacturer recommends, or running a neutral to the box.

Cause 5: a loose connection, which is the one that matters

When flicker shows up across several lights on one circuit, or a light flickers when you bump the switch or when a nearby appliance turns on, a loose connection is the likely cause. It can be a wire nut that's backed off, a backstabbed connection on an outlet or switch, or a loose screw on a breaker. Loose connections create resistance, and resistance creates heat. That's the failure that damages wiring and starts fires, which is why we don't treat circuit-wide flicker as a nuisance.

Homes with original aluminum branch wiring deserve extra attention here, because aluminum connections are more prone to loosening over time. Our guide to aluminum wiring in older Phoenix homes explains why.

When whole-house flicker means the panel or service

Flicker throughout the house that isn't tied to one fixture or one switch can come from a loose connection at the main lugs, a failing main breaker, or a problem on the utility side of the meter. We check the panel and the service connections first. If the trouble is on the utility side, we'll tell you so you can contact SRP or APS. If the panel itself is worn out, our panel upgrade cost guide explains what drives the price of replacing it.

What we check on a flicker call

• The bulb, socket and fixture driver, and whether the bulb is rated for the fixture.
• The dimmer type, its load rating and the bulbs on it.
• Every connection on the affected circuit, including switches, outlets and wire nuts.
• The breaker and its terminal, plus the neutral and ground connections in the panel.
• Voltage at the panel under load, to tell a house problem from a utility problem.

Flickering lights in Scottsdale homes

In Scottsdale we see both ends of the problem. Newer homes and remodels often have long runs of canless LED fixtures on smart dimmers, where compatibility is the usual culprit. Older ranch homes in south Scottsdale, many built in the 1950s through the 1970s, are more likely to have tired switch and outlet connections, and sometimes original panels. Same symptom, very different fix, which is why it pays to map the pattern before replacing anything.

Need flickering lights tracked down?

Tell us which lights flicker, when it happens and what kind of switch they're on, and send a photo of the fixture and your panel label if you can. We'll tell you whether it sounds like a bulb and dimmer fix or a wiring problem that needs a visit. See our electrical troubleshooting and lighting installation pages for more. B and D Electric LLC is licensed and bonded, Arizona ROC 361086, and our two owners have more than 40 years of combined experience. Call or text (480) 828-1181, or request an estimate.