What Causes High Voltage or Voltage Drop in a House?

what causes low voltage at outlet

Power surges and voltage fluctuations are not unheard of. Although grid modernization has stabilized the electric supply in many parts of the country, the electrical wires and power lines are often decades old and have difficulties carrying enough electricity to satisfy the growing demand. As low voltage and voltage fluctuations can damage your appliances and devices, let’s learn how you can protect both yourself and your home against this modern malady. 

Your power company works hard to fix any loose connection or disconnection caused by fallen trees and other natural factors that are almost impossible to predict. A part of this protection consists in modernizing the grid, correcting improper wiring, and undertaking measures to control sudden power surges. However, as there is only so much that the power company can do, you should also know that there are measures you can undertake to reduce the damage being done to your equipment. 

What is Electrical Voltage Fluctuation?

First things first: the US power grid operates on 110-120 Volts and at 60 Hz of frequency. Normally, there are several ways to preserve these frequencies and to keep the grid safe for all devices connected to it, including power generators, and solar and wind farms. However, as power use fluctuates during the day, brief periods of high or low voltage can occur as well. 

In general, high voltage can damage your appliances and devices. This is the reason circuit breakers pop when the incoming voltage is too high for the devices to handle. Once the breaker has shut off the power supply, your devices are all set, but you may need to manually turn the power back on. 

If the voltage is too low, the opposite happens. Your circuit breaker will not trip, but you will experience lights that are somewhat dimmed, heaters that do not work as strong as before, and some smart appliances that may report a low voltage error. This type of voltage is also damaging to your appliances, but it causes power generators to switch themselves off, rather than your circuit breaker. 

It is important to note that these issues can happen in certain areas only, even in certain neighborhoods, while the rest remain untouched. This is the reason you see your utility company sometimes install additional power lines in big cities. In addition to this, the grid operator favors always having 25-50% more energy-generating capacity at hand than the peak demand. These measures help stabilize the grid. 

Causes of Electrical Voltage Fluctuation

Electrical voltage fluctuation can happen for a number of reasons. The story is much more complex than the simple ratio between supply and demand and may include some more factors. Here are additional factors that can cause voltage fluctuations: 

  • Poor or loose wiring connections in the house or the mains board, 
  • Inadequate load sharing, where multiple large devices or major appliances are connected to the same power line running from a single breaker, 
  • Overloaded network – when this is expected, the utility company will issue a report to the public and ask for load reduction, 
  • Defective electrical products – usual products of older making, cheap products, or products that have been exposed to water or high humidity (never use an electrical device or appliance that has been wet), 
  • Power line interference – especially in regions with old power grids, 
  • Insufficient cable carrying capacity – which can happen both in your home or on the grid level, especially in cities and areas experiencing rapid expansion. 

Poor or Loose Wiring Connection

A loose or poor connection means that the wires that are supposed to deliver power to your electrical product are not fixed properly. This can happen due to improperly connecting the electric supply in the first place, or over years, as bolts and wires degrade or corrode. The best solution – call a handyman, and ask if they can inspect your power supply and fix what needs to be fixed. 

The best way to recognize an issue like this is to see whether your lights flicker. Flickering lights, as well as radios and TVs that produce some crackling noise, especially during storms, are usually a sign of a loose connection. Note that the loose connection can be in front of the meter as well – in which case, you should call your utility company for help. 

Inadequate Load Sharing

Inadequate load sharing can also cause voltage fluctuations. This scenario takes place when two or more major appliances are connected to the same power line. This is a common issue in older homes, where a single wire can an entire portion of a house with electricity. Adding more devices or more powerful devices in homes with poor wiring causes the load to simply be too much for the wiring that’s installed and you risk the wires overheating and starting a fire. 

Running a single power line to an entire portion of your home is a great way to save money, as electrical systems do not come at a low price tag. However, the risks are high and you may end up having to install new wiring, which costs more than running wires in the first place. For this reason, you should always invest in good wiring inspection when purchasing a new home or in proper wiring when constructing a new home. 

Overloaded Network

An overloaded network is a term that can describe two situations. Namely, the voltage fluctuation, in this case, can be seen as an electrical voltage shift that can happen both in your home and in a wider area. If the area you live in is expanding quickly, a sudden drop in the voltage level here and there is to be expected. On the other hand, if you have added a major appliance to your home (or more than one), the electrical voltage may drop in your home only. In this case, you need to call a local electrician to help you understand your specific issue and to propose the right solution. 

Defective Electrical Products

A defective electrical product can cause a light flicker effect. You may have a defective electrical product if: 

  • The product is of older making (usually heaters, radios, and television older than 15-20 years), 
  • The product is of low quality, 
  • The product was dropped, damaged, or recently repaired, 
  • The product was exposed to water or a high-humidity environment, such as a basement, 
  • The product was damaged during lightning strikes. This is usually the case if more than one product is defective when they haven’t been previously. 

In any case, you can do a test and find which device causes power spikes or drops. Go around the home, unplugging devices one by one. Once the normal power supply has been restored, the last device you’ve unplugged is the one causing trouble. Always take safety precautions, as rodents, such as mice and rats, may chew through the wiring of the said product, leaving you in danger of an electric shock. 

Power Line Interference

A power line interference is also a possibility. A power line taking power to your home’s main supply may be stressed by a branch rubbing against it, a flock of birds landing on it, animals or vehicles hitting a power pole, or significant ice deposits interfering with power delivery. In any case, extreme cases can always cause voltage fluctuation. 

Insufficient Cable Carrying Capacity

An insufficient cable carrying capacity can also cause voltage fluctuations. Namely, an insufficient carrying capacity can occur when vehicle accidents damage power lines, leaving you with fewer lines to carry electricity to the area you live in. Likewise, insufficient cable carrying capacity can also take place within your home, especially if you live in an old home or have purchased new, more powerful major appliances. 

Effects of Power Fluctuation

Sudden power surges and other forms of power fluctuations are mostly caused by a loose or poor connections. Still, there are many more causes of possible power fluctuations. But, how about their effects? Let’s dive into this now. 

Power Surges/Voltage Spikes

Power surges and voltage spikes that can be noticed in the network can be seen in your home as well. The circuit breakers that are installed between your home and the grid only trip when voltage spikes are very high, to the point that they can damage your devices, appliances and wiring. In reality, circuit breakers do not react to minor changes, although they can also damage your expensive equipment. 

Flickering Lights

Flickering lights can happen at any time when there is a power fluctuation. If this is a common occurrence, you should check whether you have faulty electric products. Electricity supply can also fluctuate when there are problems on the network itself, or when the network is overloaded. 

Decreased Equipment Efficiency

Heaters, water heaters, or other electric equipment with decreased efficiency can cause power surges and unstable voltage. A light bulb going out usually means that the breaker will trip, shutting off the power supply to the entire house. If this is the case, you need professional help: call your utility company to get educated on the most common causes of electrical issues or for an inspection of your power lines. 

Over Bright Lights

Overly bright lights can be a sign of a voltage that is too high. This usually does not happen very often, as the utility company has ways to decrease voltage remotely. If the issue persists for a longer time, make sure to unplug your sensitive or expensive appliances, as a voltage that is too high may damage them. 

Premature Globe Replacement

Voltage fluctuations can damage your globes, causing the light-emitting element to burn. If you change your lightbulbs more than once a year, it may be time to invest in lightbulbs that allow diming – these get less damaged when there are power fluctuations. Power stabilizers can also help, but maybe a bit expensive when done on a home-wide scale. 

Failure of Electronics Components

Your sensitive appliances and devices suffer a lot when there are power surges. In most cases, laptops have some form of protection, as they are not connected to the power supply directly – the charger can control some voltage fluctuations. Other equipment is best plugged out during storms, floods, or if there are significant fluctuations in a short period. 

Poor Battery Charging

Poor battery charging is another way that power fluctuations can negatively impact your electronics. Larger devices, such as laptops and tablets may take longer to charge. The same goes for your smartphone, ear pods, etc. Your home battery, if used as a backup system will take the longest, as it has the highest capacity. 

Interference of radio and tv reception

Interference with radio and TV reception can also happen when there are power fluctuations. These devices are especially vulnerable to wiring issues. Issues in power delivery to these devices can be recognized as static noise or crackling coming through the speakers. Light flicker usually accompanies these issues. 

Connectivity issues

In case there are power fluctuations, you may also experience some issues with connectivity. Many devices, such as cable phones, wireless landline phones, modems, and routers may experience connectivity issues when there are power issues and fluctuations. To prevent this, it is best to connect these low-power users to a single UPS unit. 

Reducing/Removing Power Fluctuations

For all the above reasons, it is necessary to decrease the chances of power fluctuations. There are several ways to do this, although you should bear in mind that the highest responsibility is in your utility company, as they should provide a stable and reliable power supply. The ways that you can reduce or remove power fluctuations in your home or business include: 

  1. Using UPS or other devices that can stabilize voltage fluctuations, 
  2. Avoiding power trips without surge protection, and 
  3. Setting up designated power lines for flicker-producing power loads

Use Devices to Stabilize Voltage Fluctuation

Using devices that can stabilize voltage fluctuations is the most common, and probably one of the easiest ways you can reduce voltage fluctuations. With a device such as a UPS (UPS = Uninterrupted Power Supply, or Uninterrupted Power Source), the battery in the device will supply additional power whenever the voltage is too low and will also absorb electric shocks when the voltage gets too high. 

Devices that should be plugged into a UPS: 

  • Smartphone charger, 
  • Tablet charger, 
  • Laptops, 
  • Computers
  • Lamps,
  • Modems, 
  • Routers, 
  • WiFi extenders (beware that they may not work with some devices, such as those that extend the WiFi reach by making small, purposeful power fluctuations in your home), 
  • TVs, 
  • Radios, and more. 

Avoid Using Unprotected Power Strips

Power strips with built-in power surge protection do not cost much but can protect several of your devices at once. Beware that these are a necessary part of any computer setup and that you may need to purchase one if you do not have one. Protected power strips can be purchased in many home electronic shops and computer shops for a fraction more than regular, unprotected power trips. 

Use Dedicated Lines for Flicker-Producing Loads

Your major home appliances may need a separate line. In most cases, any device over 2-2.5 kW of power needs a separate line. Electronic devices and appliances should never share a power line with lights, either. Some flicker-producing loads include: 

  • Your HVAC system, 
  • Your electric water heater, 
  • Tankless water heaters (these need a separate power line and a separate breaker), 
  • Space heaters, 
  • Water pumps, even low-wattage models, as they draw much more power than is specified for a millisecond or two to start the propellers, 
  • Your hot tub or a home spa, as they feature heaters of up to 11 kW of power, making them one of the largest electricity users in your home. 

Possible Implications of Flickering Lights

Flickering lights are just a part of the issue. The thing is that the voltage that is not stable can cause more harm than good. Surge protectors can protect from some of them, and only the appliances and devices are directly connected to them. In reality, most households have unprotected power lines, and the breakers (which should protect from power surges coming from the grid) are ineffective when faulty equipment or overloading a power line within the house takes place. Here are problems caused by flickering lights. 

Impaired vision

Over long periods, flickering lights can cause impaired vision. If you live in an area that is prone to power fluctuations, you may want to consider stabilizing the voltage coming to the lights. This will help you preserve your eyesight and save hundreds, if not thousands, in medical checkups and purchasing glasses. 

Human fatigue

Fatigue, nausea, and headaches are all symptoms that can develop due to flickering lights. The thing is that these symptoms can appear as a consequence of your cornea having to adjust its size all the time with flickering lights. This directly translates to headaches and fatigue, even migraines after a long time in a place like this. 

Reduced Concentration

Headaches, migraines, fatigue, and nausea lead to reduce concentration. This can then cause poor school or work performance and may even lead to more serious concentration issues. In fact, studies have connected bad lighting with reduced concentration. 

Avoidable accidents

In addition to reduced concentration and focus, you are also more likely to be in a car accident if your light is not good enough. The thing is that over longer periods fatigue may build up and make you more irritable, reduce your judgment and increase the likelihood of ending up in a car accident. The same can happen when you are home: the ladder, climbing and descending a staircase, and operating machinery all pose some level of danger. 

Vision discomfort

Vision discomfort, having a feeling of dry eyes, sand in your eyes, and other similar vision discomfort may occur as well. Some people may think that computers and TVs are to blame, but lights can also pose a big issue here. Artificial tears and spending time outdoors may help reduce these symptoms until you install a surge stabilizer. 

Decreased productivity

The same problems that flickering lights cause can cause other issues as well. Decreased productivity is one of them. Fatigue, nausea, changes in the sleep pattern, as well as irritability, headaches, etc., can all have a pronounced negative impact on your work productivity. The same goes for students, at any level of education. 

Premature globe replacement

Premature globe or light bulb replacement is another common issue that may take place if you have problems with an unstable power supply. In most cases, this will present an unwanted and unnecessary expenditure on your part. The same is especially true if you use halogenic or LED lights in your home, as they cost more than incandescent light bulbs. 


How Often Should a Whole House Surge Protector be Replaced?

Your whole house surge protector can generally last anywhere between 5 and 10 years. However, if you live in an area where issues with power surges occur frequently, you may want to switch your device every 2 years. This will give you certain protection in the case of a surge or low voltage. 

Does Voltage Fluctuations Affect AC?

Yes, electric fluctuations affect AC. Most of your appliances have built-in protection, however, fluctuations that are too high may cause your AC unit to work with reduced performance. Over time, fluctuations can cause damage that builds up and reduce the useful life of your unit. 

Are LED Lights Flicker Free?

No, LED lights are not flicker-free. These lights can easily flicker, just as halogenic or incandescent can. Halogenic lights are the slowest to react to changes in voltage or amperage of the electricity entering your house, and the flickering effects will not be as pronounced. 

Can Flickering Lights Cause a Fire?

Lights rarely, if ever, cause fire, even if they flicker. However, flickering lights may pinpoint some other issues in your home electricity network that may cause a fire, such as faulty or poor wiring or damage to electrical devices and appliances. If you notice flickering lights, contact an electrician right away. 


Flickering lights occur in all homes at a certain point. However, if you notice the unusually frequent light flicker, regular flicker, or repetitive flickering of lights, this could point to certain issues that should be resolved as soon as possible, such as mistakes in the electrical system of your home, faulty, old, rusty, or otherwise damaged electrical wires or a low voltage as a result of a new or an old and faulty major appliance being connected to the network. 

Light flicker is not welcome in any home, especially as it may cause other issues, such as health-related issues to the eye and headaches, nausea, and a lack of focus and concentration. Decreased productivity and a higher likelihood of ending up in vehicle accidents are all reasons to consult a professional to inspect your home electrical wiring and find the cause of any sudden drop in the voltage level. 

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