Why do lights flicker? Top reasons behind this common problem

Flickering lights can be a simple case of a loose bulb or an incompatible dimmer switch. In other cases, it could point to overloaded circuits, faulty wiring, or even arcing, leading to power failures, appliance damage, or electrical fires.

Addressing the underlying cause of flickering light early can prevent costly repairs and ensure your home’s electrical system remains safe and reliable.

In this guide, we’ll answer the commonly asked question: Why do lights flicker? We’ll also explain how to diagnose the issue yourself, fix simple causes of light flickers, and know when to call an electrician.

What causes lights to flicker?

A flickering light indicates an underlying electrical issue that needs attention. Sometimes, the fix is simple, like tightening a loose bulb, but persistent flickering could point to a larger problem. Understanding the cause is key to finding the right solution. 

So, what causes lights to flicker? Here are some common reasons and how to fix them.

Loose bulbs or connections

When a bulb isn’t screwed in tightly, or the electrical connection is weak, the circuit can lose contact and cause flickering. This is especially common with screw-in bulbs. To fix this, turn off the power to the fixture and carefully tighten the bulb to ensure a secure connection. 

If the flickering persists, remove the bulb and check for debris or corrosion in the socket. If you notice any, clean it gently with a dry cloth. If you've tried all of this and it doesn't help, consider replacing the bulb to eliminate the possibility of a defect.

Power fluctuations

If tightening the bulb doesn't resolve the issue, you might be asking, "Why do my house lights flicker?" The cause could be a power fluctuation, which can occur when the voltage supply is inconsistent.

Voltage fluctuations can cause lights to flicker, especially when high-powered appliances like air conditioners or refrigerators are turned on. If this happens, try plugging the appliance into a different circuit to balance the electrical load. 

On the other hand, if multiple lights flicker throughout the house, it could be due to utility grid issues. In this case, check with your power company to see if there are any problems or outages in your area. 

If the flickering is severe or constant and you have confirmed it’s not from your power company, it may indicate an overloaded circuit or faulty wiring. In this case, you should hire an electrician to inspect your home’s electrical system.

Dimmer switch incompatibility

Not all dimmer switches work well with LED or CFL bulbs; some older ones are designed for incandescent bulbs and don’t adequately regulate the lower wattage of modern LEDs. If you're using incompatible bulbs, you might notice flickering, buzzing, or uneven dimming. To fix this, check if your bulbs are labeled “dimmable” and replace them if necessary. If your dimmer switch is outdated, upgrade to an LED-compatible dimmer switch.

More serious causes of flickering lights

Persistent flickering, especially across multiple lights, indicates more serious causes, like overloaded circuits, aging or faulty wiring, or electrical arcing. Here’s how to identify the issue and what to do.

Overloaded circuits

An electrical circuit is designed to handle only a specific amount of power. Too many appliances or high-wattage devices connected to the same circuit can overload it, leading to flickering lights. These overloaded circuits can cause wires to overheat and melt their insulation, creating a serious fire risk. 

If your outlets or switches feel warm to the touch or breakers trip often, your electrical system may need an upgrade to redistribute power across circuits. This major electrical work requires a licensed professional with an electrical permit to assess the load and work on the upgrade.

Old or faulty wiring

Electrical wiring deteriorates over time due to aging, corrosion, or rodent damage. This faulty wiring can cause intermittent power loss and flickering lights throughout the house. 

If flickering occurs in multiple rooms, along with frequent electrical shocks when touching switches, buzzing sounds from outlets, or a burning smell, it’s a faulty wiring issue. 

Faulty wiring is one of the leading causes of house fires, often hidden inside walls until it’s too late. If you notice any of the signs, you should hire an electrician to inspect and fix the wiring.

Arcing and its dangers

Arcing occurs when electrical current jumps between loose or broken connections. Unlike overloaded circuits or aging wiring, arcing doesn’t just cause flickering. It also produces crackling or sizzling sounds and even scorch marks near outlets. 

Unfortunately, arcing can go unnoticed in homes without Arc Fault Circuit Interrupters (AFCIs) until a fire starts. 

If your home lights flicker erratically, especially when turning a switch on or off, it may indicate an issue. You might also notice burning smells, frequent breaker trips, or hear buzzing or crackling sounds from outlets. These could be signs of arcing. You should call an electrician immediately to inspect the wiring and replace damaged connections.

Troubleshooting your flickering lights

Here are simple steps to diagnose flickering lights before calling an electrician: 

• Tighten the bulb: Is the light bulb flickering? Turn off the switch and tighten the bulb. If it continues to flicker, replace it with a new one.
• Check your dimmer switch: LED lights flickering could be caused by an incompatible dimmer switch. Ensure it is LED-compatible. If not, you can replace it with a dimmable LED or CFL bulb, or upgrade to an LED-compatible dimmer switch..

• Test with a different outlet: Does flickering only occur when turning on a high-powered appliance? Plug it into a different outlet or use a different circuit. If the flickering stops, the circuit may be overloaded. Ongoing flickering could indicate a problem with your home’s electrical panel or wiring.
• Inspect the outlet: A warm outlet, buzzing noise, or sparks when plugging in a device likely point to a loose or damaged connection. 
• Replace faulty switches: Is there a light flicker when toggling a switch? If so, the switch may be faulty. Replacing the worn-out outlet or switch should solve the issue.
• Check your electrical panel: Look for tripped breakers in your electrical panel. Resetting the breaker only to see flickering again suggests an overloaded circuit. Should you notice scorch marks, a burning smell, or hear buzzing from the panel, turn off the power immediately and call an electrician.

How to check for loose connections or bulbs

If you suspect your lights are flickering because of a loose connection, here’s what to do:

• Turn off the light switch to avoid accidental shocks or burns.
• Carefully twist the bulb clockwise until it is securely in place, but avoid over tightening, as this can damage the socket.
• When tightening doesn’t fix the issue, replace the bulb with a new one. Does the flickering stop? Then the old bulb is likely faulty. If it continues, the problem may be with the fixture or wiring.
• Look inside the socket for signs of corrosion, discoloration, or damage. Should it appear worn or discolored, repair or replace the fixture.
• Are you dealing with a plug-in lamp or light fixture? Insert the plug fully into the outlet.

When to contact an electrician

When you have tried all the troubleshooting tips and your lights still flicker, it’s time to call an electrician. Here are other signs that it’s time to do so.

• Flickering in multiple rooms or the whole house.
• Frequent or worsening flickering.
• Burning smells or scorch marks.
• Buzzing, sizzling, or crackling sounds.
• Breakers that trip frequently.
• Outlets or switches that feel warm.
• Lights dim when appliances turn on.
• Sparks from outlets or switches.
• Visibly outdated or deteriorating wiring.

Why do light bulbs flicker and when should I be worried?

Flickering lights might seem minor, but they signal underlying electrical problems that can threaten your home and safety.

As such, it’s strongly recommended that you address it promptly. Most causes of flickering light are fixable on your own. 

However, safety should always come first. Call a licensed electrician immediately if troubleshooting doesn’t resolve the flickering or you notice other warning signs, such as burning smells, warm outlets, or frequent breaker trips.