How do I fix flickering lights? Lights going off and on and dimming is a nuisance. But the fix is usually easy if you check 12 important things.
I’m going to go over several easy fixes you can check yourself.
Then, if the easy fixes don’t work, I’ll go over what your electrician and local utility can do. Your utility is the company you pay your electricity bill to.
I’m certain one of these fixes will work.
Before we start though, have an answer ready to the following questions:
- Are lights from only one circuit flickering?
- Do lights on multiple circuits flicker at once?
- Where is the location of the flickering lights?
- Are lights flickering, or dimming?
- Do some lights get dimmer while others get brighter?
- Do all lights on a circuit flicker, or just a couple?
- Is it the same lights that are flickering over and over again?
- Is the problem seasonal?
By answering these questions, you can better troubleshoot using the 12 suggested fixes.
Important Note: turn off circuits or disconnect any electronics before troubleshooting. You don’t want to damage any equipment when you’re disconnecting and reconnecting wires.
Troubleshooting and fixes you can do
The easy fixes are troubleshooting techniques you can check and do yourself. You don’t need any outside help.
To point out, generally speaking, flickering lights happens from loose connections. The electrical connection you can think of as going from off to on.
Whereas dimming happens when not enough current reaches your light. I’ll go over light flickering and dimming in detail with each troubleshooting approach.
Troubleshooting Approach #1: loose light bulb in a socket
Check if your light bulb is tightly screwed in.
This seems like a no-brainer, but it’s often overlooked. Over time light bulbs in a socket can become loose.
So, try gently wiggling the light bulb in the socket and see if it flickers. If it does, you’ve spotted your problem. So just tighten the light bulb.
If tightening the light bulb doesn’t work, replace the light bulb. The light bulb may have internal damage.
The same applies to loose light plugs. There may be a loose connection between a plug and a wall outlet. Thus, check to see if your lamp’s plug is firmly in the wall socket.
Troubleshooting Approach #2: high load inrush current
When motors or any large inductive loads turn on, they draw A LOT of current. In return, there’s a voltage drop in the connected circuit.
This high inrush current can be from an HVAC unit or even a dryer. In this period of high inrush current, your lights may momentarily dim.
What’s more, similar dimness and flickering can happen from cooktops or microwaves. Some of these appliances operate by switching on and off at around a 1-hertz rate.
For example, a microwave will cycle power on and off given its set timer. This can cause a voltage to drop in the connected circuit.
Then, there are some old washers that can cause lights to dim and flicker too. This happens when their motor reverses direction every half second. In agitator mode, the current draw will vary, causing voltage fluctuations.
If a light bulb sees voltage fluctuations as low as even 5 volts, you’ll see flickering.
In short, if your lights dim and/or flicker when these loads startup and run, you’ll know your problem. One quick fix is to place these loads on a dedicated circuit. Otherwise, it’s a normal temporary issue you just deal with.
Important Note: think of the water system in your house. Imagine you’re taking a shower and then someone flushes the toilet.
All of a sudden, you notice the shower water pressure drops. This happens because a single water pipe feeds both your toilet and shower.
Similarly, think of voltage as electrical pressure. Voltage pushes current through an electrical line. So if there’s a high current draw from a motor start, the voltage will drop across all other circuit loads.
So a large motor starting is like someone flushing the toilet.
For example, an AC compressor may draw 125 amps for a few milliseconds. Thereafter, it’ll reach a steady-state current of 25 amps a couple of seconds later
So, an instant momentary voltage drop happens when the AC compressor turns on. Thus, your lights may then momentarily dim.
Troubleshooting Approach #3: LED light bulb condition
Do you have an LED light bulb installed?
LEDs are Light Emitting Diodes. They only allow current to flow in one way.
In other words, LEDs use Direct Current (DC) to operate. While most regular lights can use Alternating Current (AC) to operate.
LEDs work because they use AC to DC converters to operate when connected to AC.
Without the converter, an LED will only be lit when the current flows in the right direction using AC. As a result, the LED light bulb will flicker.
So if flickering happens, this means your LED light bulb may have internal damage.
By replacing the LED light bulb, you’ll probably fix your light flickering problem.
One quick test is to swap out your LED light with an incandescent light bulb. If the incandescent light bulb doesn’t flicker, your LED light bulb is your problem.
Important Note: typical LEDs want roughly 2 volts DC across them. The voltage varies depending on the light’s color.
The current draw can then range from a few milliamps to several amps. That’s a 1000X swing. Due to this huge current variance, LEDs need a controlled current source.
An LED light bulb you buy will have built-in circuitry to handle such current variances.
Troubleshooting Approach #4: LED light bulb dimmer
Is your LED light bulb designed with dimming capabilities?
Because you can’t hook up all LED light bulbs to dimmer switches.
Non-dimmable LEDs are either fully on or off. The circuitry design isn’t made to handle low current levels.
Whereas dimmable LEDs can respond to varying current levels.
Thus, check to see which type of LED light bulb you have installed. Also, check the specs of your dimmer.
Was your dimmer originally connected to incandescent light bulbs? If yes, your dimmer probably isn’t compatible with LED light bulbs. Especially if your home pre-dates 2010.
Important Note: there are two types of dimmers.
Leading edge: designed for incandescent light bulbs. They’re the most common dimmers found in homes. These dimmer designs work with high-wattage loads, which incandescent light bulbs are. But, LED light bulbs are low-wattage. Thus, these dimmers can’t “control” their circuitry well.
Trailing edge dimmers: designed specifically to work with LED light bulbs. They have a much lower wattage range. Thus, they can “control” LED light bulbs effectively.
Electrician troubleshooting and fixes
These are electrical tests and fixes you can’t do yourself. You’ll need to get outside help.
For these troubleshooting techniques, call a qualified electrician.
Troubleshooting Approach #5: electrical panel voltage measurements
First, have your electrician take voltage measurements inside your electrical panel.
Measure directly on the wires that enter your main panel at your main breaker.
From this measurement, you’ll know if a problem is inside or outside of your home.
It’s always important to work your way in or out of a house. The size of the home doesn’t matter either. The process is the same.
To start, the measured line-to-line voltage should be 240 volts.
If the 240 volts evenly drops for both legs, it’s probably a utility transformer problem. Maybe the transformer is too small or just old.
If only one hot leg has a voltage drop and the other measures 240 volts, there’s a problem only with the one leg. Maybe there’s a bad splice from the transformer to the panel on that one leg.
But what if there’s only a small voltage variation on both legs? At this point, the electrician needs to take other measurements. This includes measuring the line to neutral, 120 volts, to each hot leg.
Check if the voltages drop or if there’s an imbalance. For example, one side may have a higher voltage reading than the other.
If this is the case, there’s a neutral problem from the meter box to the utility transformer. The neutral problem can be in any one of the following places:
- In the transformer
- Wire routing from the transformer to the metering box
Finally, the electrician should connect a multimeter to the circuit with flickering lights. Then record the minimum and maximum voltage to see if the problem is inside the panel or downstream.
Important Note: a quick trick is to get two matching incandescent light bulbs. Get low-wattage light bulbs, like 15 watts, so they’re easy to stare straight at.
Connect one light bulb to each phase at the main panel. Then hold them next to each other and watch for the following to troubleshoot:
- Both light bulbs flicker: a problem at the panel or upstream with utility equipment.
- One light bulb flickers: a faulty leg in the main panel.
- One light bulb gets dimmer while the other gets brighter: a neutral problem.
- Both dim or brighten together: a problem with utility equipment.
What I’ve listed are only some suggested problems with each case scenario.
Troubleshooting Approach #6: thermal imaging inspection
Have your electrician search for hot spots using thermal imaging.
This will give you accurate information on where further to inspect.
Maybe you had a short circuit inside your panel, that caused damage. Thus, causing lights to flicker.
Important Note: hot spots are areas with greater temperatures than their surroundings. Inside homes, hot spots are commonly found in walls, ceilings, and appliances.
Also, they’re typically caused by the following electrical problems:
- Short circuits
- Poor insulation or degraded wire insulation
- Overloaded circuits
Troubleshooting Approach #7: feeder wire connection check
Have your electrician check for any loose wires.
I’ve found loose wires are common with poor neutral bus bar connections.
To troubleshoot, electricians will remove panel breaker covers. Then they’ll check the wiring connected to the neutral bus bar. Be sure they check for any hairline breaks in the neutral bar too.
If everything checks, the electrician needs to tighten all screws on the bus bar. This includes the main lugs in your panel.
Next, they need to check for loose circuit breakers. Also, any loose wires coming out from the circuit breakers.
Finally, the electrician needs to check switch boxes.
Maybe you slammed a door too hard and loosened a neutral connection in a switch box.
When you have a loose connection, vibrations can cause flickering lights. Let’s say you’re doing heavy home repair work, or if your kids are jumping around on the second floor.
The only way to be certain is to remove switch cover plates and check if the wires are secure under their wire nuts.
Important Note: if you have an old house, you may have aluminum wires in your panel. These days, most all new homes need to use copper wire by code.
To point out, copper is orange in color, while aluminum is greyish in color.
The problem with aluminum wires is that they can oxidize. This leads to a high impedance connection. As a result, not enough current may reach a light. The bigger issue is cold flow though, where the aluminum wire loosens out from a connection.
To remedy this issue, an electrician will disconnect and clean the affected wires. They’ll then apply a non-oxidizing protective coating before reinstalling the wires.
One other easy lighting test is to swap the wires from a problem circuit to a working circuit of equal ampacity. Then check if the lighting problems continue.
If they do, you probably have a loose wire connection in one of the circuit boxes in your home. For example, your switch box in your wall.
Troubleshooting Approach #8: main wire connection check
Have your electrician check connections between your service wires and your main breaker. The wires may be loose.
Also, have them check for loose connections between your main breaker and the bus bar.
By removing a panel cover, electricians can check all wire connections. As well, they can check for any burn damage inside your panel.
Local utility troubleshooting and fixes
If your electrician can’t figure out your problem, the next step is to go to your local utility.
Your local utility owns the equipment that may be causing the next set of issues I’m going to discuss.
Keep in mind, they’ll want to fix any issues caused by them as soon as possible. Because they’ll need to pay for any of your damaged household appliances. Or even worse, pay for any brownouts or fires caused by their equipment.
So, call your utility company and explain your situation. They’ll quickly then come out and do their investigation.
Important Note: if only a single light flickers, it’s an isolated issue. You probably only have a loose connection as discussed in earlier troubleshooting approaches.
But, if all lights flicker in your house, you probably have a power utility issue.
Troubleshooting Approach #9: record incoming voltage
Have your local utility set up a recorder to monitor your voltage over a 24 hour period. This will help spot any voltage drops in your home.
This should be the first approach if nothing instantly catches the utility reps’ eyes.
Troubleshooting Approach #10: loose wire connection check
The local utility should check for any loose wire connections at your meter box.
Your meter box is more than likely mounted on the side of your home. Also, it’s in the jurisdiction of your local utility. So it’ll have a lock on it, preventing you and your electrician from getting inside.
I’ve seen cases where the utility has come and replaced the entire meter box due to old age. This brought the meter box up to the current code and fixed all the flickering light issues.
Troubleshooting Approach #11: utility transformer damage
The pole-mounted transformer feeding your neighborhood may have internal damage.
If this is the case, your neighbors will experience the same flickering light issues.
So go ask your neighbors. See if they’re experiencing flickering lights too. If they are, your lighting problems are probably from your utility’s transformer.
To fix the problem, your local utility will send a lineman to check the overhead connections. Maybe there’s a loose transformer connection. This will explain why you have lighting issues only on windy days.
Just as likely, the entire transformer is old and needs replacement.
What’s more, have the utility check the voltage on the ground lead. They may find a high voltage reading. This may be indicative of a possible loose neutral connection at the transformer.
Important Note: the local utility may not find any issues in their visit. They’ll visit the transformer and say everything is fine.
But, this doesn’t mean everything is okay. There may be a loose connection that only wobbles in storms. Let your local utility know this.
Also, let them know if you hear a buzzing sound from the transformer.
The point is, don’t let them put you off. Bad transformer connections can damage equipment and cause fires.
Troubleshooting Approach #12: overloaded utility transformer
The power system in your neighborhood may not have been properly designed.
Let’s say the utility adds extra loads to the transformer that feeds your home. All the while, they didn’t upsize their equipment. PLUS, one of the new loads is a decently sized motor.
To point out, every transformer rating can only output a given amount of current. So due to the starting of the new motor, your house may get a momentary drop in current.
The same issue I discussed with appliances in Approach #2, now applies to loads outside of your home.
It’s important to realize, a utility transformer typically feeds an entire neighborhood. Not just your home.
Maybe your utility transformer is also feeding a small business that runs a large motor. So when this motor starts up, all other transformer-connected lighting loads would dim.
To address this, a utility would need to do load calculations. They’ll need to determine if they need to upsize their transformer or not.
Important Note: the larger a transformer, the easier it can supply a set current. All the while, having a minimal voltage drop.
Just as important, a smaller transformer has smaller-sized wires. And smaller wire sizes cause voltage drop for higher than rated current flow.
Another factor is the length of the conductor run from the transformer to your home. You can better visualize this conductor length variable in a voltage drop calculation.
“How do I fix flickering lights?” wrap up
Follow these 12 troubleshooting approaches, to fix almost any lighting issues. I guarantee it!
And I know, some of these troubleshooting approaches can become overly complex.
BUT, you only need to do your part. Start with the easy fixes.
A lot of the time, you won’t even need to call for outside help.
If the easy fixes don’t work though, call a professional who will do all the heavy lifting for you. Just be sure you answer all the questions I outlined at the top of this article.
Provide as much information as possible to your electrician and the local utility. They’ll then better be able to troubleshoot your problem.
Plus, you can now even direct your electrician and local utility on what to look for.
How do you typically fix flickering lights? What do you typically find is the cause of flickering and dimming lights?
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Koosha started Engineer Calcs in 2020 to help people better understand the engineering and construction industry, and to discuss various science and engineering-related topics to make people think. He has been working in the engineering and tech industry in California for over 15 years now and is a licensed professional electrical engineer, and also has various entrepreneurial pursuits.
Koosha has an extensive background in the design and specification of electrical systems with areas of expertise including power generation, transmission, distribution, instrumentation and controls, and water distribution and pumping as well as alternative energy (wind, solar, geothermal, and storage).
Koosha is most interested in engineering innovations, the cosmos, our history and future, sports, and fitness.