Why Your Lights Flicker (And When It's Dangerous)

Flickering Lights: Harmless Annoyance or Warning Sign?

You are sitting in your living room and the lights dim for a second, then come back. Maybe it happens when the furnace kicks on. Maybe it happens randomly. Maybe it has been happening for months and you have just gotten used to it. Flickering lights are one of the most common electrical complaints from homeowners in Racine, Kenosha, and throughout southeastern Wisconsin — and the cause ranges from completely benign to genuinely dangerous.

This guide will help you figure out which category your flickering falls into and whether you need to call an electrician.

Harmless Causes of Flickering Lights

Some flickering is normal and nothing to worry about:

Large Appliances Starting Up

When your central air conditioner, furnace blower, or refrigerator compressor kicks on, it draws a brief surge of current — called inrush current — that can cause a momentary dip in voltage throughout the house. If your lights dim for just a second when a major appliance starts and then return to normal, this is usually harmless. It is especially common in older Wisconsin homes where the electrical system was not designed for today's appliance loads.

However, if the dimming is severe (lights drop to half brightness) or prolonged (more than a second or two), it may indicate an undersized panel, a weak connection, or a circuit that is at capacity.

LED Bulb Compatibility Issues

LED bulbs are wonderful for efficiency, but they can flicker if paired with an incompatible dimmer switch. Older dimmer switches designed for incandescent bulbs do not always work properly with LEDs. The fix is straightforward: replace the dimmer with one rated for LED use. Check the LED bulb packaging for a list of compatible dimmers, or ask your electrician for a recommendation.

Loose Light Bulb

Before worrying about your wiring, check the obvious: is the bulb screwed in tightly? A bulb that is not making solid contact with the socket will flicker. Turn off the fixture, let the bulb cool, and tighten it. If that fixes the problem, you are done.

Causes That Need Attention

These causes are not immediately dangerous but should be addressed by a licensed electrician:

Loose Wiring Connections

This is the most common cause of persistent flickering and the one most often overlooked. A loose wire nut, a backstab connection that has worked itself free, or a corroded splice can create an intermittent connection that causes flickering. The danger is that loose connections generate heat, and over time that heat can damage insulation and create a fire risk.

Loose connections can be anywhere in the circuit — at the switch, at the outlet, at the fixture, at a junction box in the attic, or at the breaker in the panel. Finding the loose connection requires systematic troubleshooting by a licensed electrician.

Overloaded Circuit

If lights flicker when you turn on other devices on the same circuit — a hair dryer, a space heater, a vacuum — the circuit may be overloaded. Modern code requires dedicated circuits for many high-draw devices, but older homes often have multiple rooms on a single 15-amp circuit. The solution is adding a dedicated circuit, which requires an electrician.

Outdated or Damaged Switch

A worn-out light switch can cause flickering in the fixtures it controls. If the flickering only happens with one switch, and jiggling the switch changes the behavior, the switch itself is the problem. Replacing a standard switch is a straightforward fix.

Dangerous Causes — Call an Electrician Now

These situations require prompt professional attention:

Flickering Throughout the Entire House

If lights flicker in multiple rooms simultaneously and it is not tied to a large appliance starting, the problem may be at the main panel, the service entrance, or the utility connection. Possible causes include a loose main breaker connection, a corroded meter base, or a failing utility transformer. This is a serious issue because the problem point is carrying your entire home's electrical load, and a loose connection at that scale generates significant heat.

Flickering Accompanied by a Burning Smell

If you smell something burning — hot plastic, rubber, or an acrid chemical smell — combined with flickering, you have an active overheating situation. Turn off the affected circuit (or the main breaker if you cannot isolate it) and call an electrician immediately. Do not wait to see if it goes away.

Flickering With Warm or Discolored Outlets or Switches

If an outlet or switch plate is warm to the touch, or if you see brown or black discoloration around it, there is an overheating connection behind the plate. This is a fire hazard. Stop using that outlet or switch and call an electrician.

Flickering After a Storm

Wisconsin storms — especially the severe thunderstorms and ice storms that hit the Racine-Kenosha area — can damage the service entrance, loosen the utility connection at the weatherhead, or cause tree branches to interfere with the service drop. If flickering starts after a storm, have both your utility company and an electrician check the connections.

DIY Checks You Can Do Safely

Before calling an electrician, you can safely check a few things:

• Tighten the bulb. Turn off the fixture, let the bulb cool, and make sure it is seated firmly.
• Try a different bulb. A failing bulb can flicker before it dies.
• Check the dimmer switch. If the flickering fixture is on a dimmer, try a different LED-compatible dimmer or try a non-dimmable fixture to isolate the issue.
• Note the pattern. When does the flickering happen? Which fixtures are affected? Does anything trigger it? This information helps your electrician diagnose the problem efficiently.
• Check with neighbors. If your neighbors are also experiencing flickering, the problem is likely on the utility side. Contact We Energies to report the issue.

Frequently Asked Questions

Is it normal for lights to flicker when the AC turns on?

A brief, slight dimming when the air conditioner starts is common and usually not a concern — the AC compressor draws a large inrush current that momentarily affects the voltage. However, if the dimming is severe, lasts more than a second, or is getting worse over time, have an electrician evaluate your panel and the AC circuit. A soft-start device on the AC compressor can also reduce or eliminate the voltage dip.

Can flickering lights cause a fire?

Flickering lights themselves do not cause fires, but the underlying cause can. Loose connections, which are a common cause of flickering, generate heat at the point of poor contact. Over time, this heat can char wire insulation, melt plastic components, and ignite nearby combustible materials. That is why persistent flickering should always be investigated — it can be an early warning sign of a connection that is slowly deteriorating.

How much does it cost to fix flickering lights?

The cost depends entirely on the cause. A dimmer switch replacement might cost $100 to $200. Diagnosing and repairing a loose connection in a junction box might run $150 to $350. If the problem is at the main panel or service entrance, costs can range from $300 to $1,000 or more. An electrician can usually diagnose the cause within the first visit and give you an accurate quote before proceeding with the repair.

Flickering lights making you nervous? Call Couillard Electric at (262) 618-2851 for a free estimate. We diagnose and fix electrical issues for homeowners throughout Racine, Kenosha, and southeastern Wisconsin.