It is a common scenario in many Denver homes: you are sitting in the living room reading a book, the central air conditioner kicks on, and for a split second, the lights dim or flicker. Or perhaps you turn on the microwave, and the kitchen lights momentarily lose their brightness.
While a slight, momentary dimming is often normal, severe or persistent flickering is a warning sign from your electrical system. Understanding why this happens can help you determine if it is a harmless quirk of your home or a serious electrical hazard that requires a licensed Denver electrician.
The Science Behind the Flicker: Inrush Current
To understand why lights dim, you have to understand how large appliances consume electricity. Appliances with large motors—such as your air conditioner, heat pump, refrigerator, or a well pump—require a massive surge of power to start up.
This initial surge is known as “inrush current” or “starting amperage.” When a heavy-duty motor starts, it can pull three to five times more electricity in the first few milliseconds than it uses while running continuously.
Because your home’s electrical system has a finite amount of power available at any given moment, this sudden, massive demand for electricity causes a temporary drop in voltage across your entire electrical system. Your lights, which are very sensitive to voltage changes, react to this drop by momentarily dimming. Once the motor is running and the power draw stabilizes, the voltage returns to normal, and the lights brighten again.
When is Flickering Normal?
A brief, barely noticeable dimming (lasting less than a second) when a large appliance like an AC compressor turns on is generally considered normal, especially in older homes. If the dimming is slight and only happens during the exact moment the appliance starts, it is usually just the natural physics of inrush current at work.
When is Flickering a Warning Sign?
However, if the flickering is severe, lasts for more than a second, or happens under different circumstances, it indicates a problem that requires professional attention. You should contact an electrician if you experience any of the following:
1. The Lights Dim and Stay Dim
If the lights dim when an appliance turns on and stay dim the entire time the appliance is running, you have a serious capacity issue. This means the appliance is continuously drawing more power than the circuit (or your entire electrical panel) can safely provide. This is a common sign that your home needs an electrical panel upgrade, particularly if you are still running on a 100-amp service.
2. The Lights Flicker When Small Appliances Turn On
It takes a massive motor to cause a normal voltage drop. If your lights flicker when you turn on a relatively small appliance—like a vacuum cleaner, a television, or a blender—there is a problem. This often indicates a loose neutral wire or a failing connection somewhere in the circuit.
3. The Flickering is Accompanied by a Buzzing Sound
If you hear a buzzing or crackling sound coming from the light switch, the outlet, or the breaker box when the lights flicker, turn off the power to that area immediately. Buzzing indicates electrical arcing—electricity jumping across a gap between loose wires. Arcing generates extreme heat and is a leading cause of electrical fires.
4. Only One Specific Light Fixture Flickers
If the flickering is isolated to a single lamp or room, the issue is likely localized. It could be a loose lightbulb, an incompatible dimmer switch (very common when switching to LED bulbs), or a loose wire connection inside the light switch box.
How a Professional Electrician Fixes the Problem
If your lights are dimming severely when the HVAC system turns on, the licensed electricians at JM Electric can implement several solutions:
- Installing a Hard Start Kit: For air conditioners, we can install a capacitor (often called a hard start kit) directly on the AC compressor. This acts like a battery, providing the initial jolt of electricity the motor needs to start, preventing it from pulling that power from the rest of the house.
- Running Dedicated Circuits: If your microwave and your kitchen lights are on the same circuit, they will fight for power. We can run a new, dedicated circuit specifically for the heavy appliance, isolating its power draw from the lighting circuits.
- Upgrading the Electrical Panel: If your home’s total capacity is simply too low to handle modern demands, upgrading to a 200-amp electrical panel will resolve the voltage drops and ensure your home is safe.
Don’t ignore the warning signs your electrical system is giving you. If you are concerned about flickering lights in your Denver home, contact JM Electric for a thorough safety inspection. You can also find us on JM Electric on Google Maps.