Electrical Circuit Overload: What Causes It and How to Prevent It

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During the Christmas holidays and throughout winter, an average home in the United States tends to use more electricity over the rest of the year. Many would deck their homes with Christmas lights and holiday decorations and heaters would become a necessity. 

According to the estimates of energy company Arcadia, around 3.5 billion kWh are used in the month of December in the country to power Christmas lights. This doesn’t count the heaters or furnaces that use electricity to operate. That said, it wouldn’t be surprising if more homes experience electrical issues over the winter months, such as an electrical circuit overload. 

Also read: 12 Electrical Safety Tips for the Holidays

Ever experienced your outdoor light displays suddenly going out after you plugged in an appliance? And maybe, it’s not only the Christmas decors that went off. You probably lost power in an area in your home, too. What just occurred may probably be an electrical circuit overload.

Understanding Your Home’s Electric Circuit

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Before we take a look at how an overload happens, it’s good to understand what comprises an electrical circuit. 

The electric circuit in your home consists of the following: 

  • Wiring: The wires in a home’s circuit include a hot wire (usually colored black) that goes from the main electric panel to lights, receptacles, or electrical devices, a neutral wire (usually colored white), which carries the circuit back to the main panel, plus a grounding wire that also returns to the panel and to the earth.
  • Breaker: These are electrical switches that are designed to interrupt the current flow in case of an overload or a short circuit. You can find the circuit breakers in your circuit breaker box. 

If you live in an older home, your wiring system might still use fuses instead of circuit breakers.

  • Devices: These include light fixtures, appliances, electronics, or anything that is plugged into an outlet.

Further read: Home Electrical Basics: 8 Things Every Home Owner Should Know

Why does a circuit overload happen?

Your home’s electrical circuits are designed to carry a certain amount of electricity. Each appliance, fixture, or electrical device that is plugged into an outlet adds to the overall load on the circuit. When the load exceeds the amount, the circuit breaker will trip and will shut off the power to the entire circuit. 

So for example, you plugged in a microwave and suddenly the power in your kitchen and outdoor lights went off, it is possible that your kitchen appliances and your holiday decorations are all connected to the same circuit. Having them running all at once exceeded the capacity of the electrical wiring.

When you lose power, it only means that the circuit breaker is doing its job of automatically disrupting the current flow to prevent any more damage to the electrical circuit. This is actually good news, and you can simply reset the circuit breaker to restore the flow of electricity. However, outdated breaker boxes that have worn out connectors that don’t work properly could cause the wiring to overheat, melt the wire insulation and start an electrical fire.

This is why even though you can rely on your circuit breakers to prevent any further damage, you should still be careful not to overload your circuits — most especially at this time of the year when many households use more power than usual. 

What are the signs of an overloaded circuit?

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As mentioned above, the most common tell-tale sign of an overloaded circuit is a tripped breaker, which means losing power. However, there are also less unnoticeable signs of an electrical system overload, such as:

  • Dimming or flickering lights, which happens when you plug in or operate an appliance, or when you turn on more lights
  • Switches or receptacles are warm to touch
  • Buzzing sound coming from switches or outlets
  • Strong burning smell coming from outlets or switches
  • Visible scorch marks on outlets or plugs
  • Operating appliances or electronics that are plugged in seem to lack power

Do note that buzzing or crackling sounds, burning odor, and devices turning unusually warm are also symptoms of other wiring problems or short circuits. If these issues continue to persist, contact a licensed electrician immediately.

3 Sure Steps to Prevent Electrical Circuit Overload

Take these three easy-to-follow steps to help you prevent occasional blackouts due to your breaker tripping and more importantly, prevent chronic circuit overloading. 

Step 1: Map out your home’s circuits

To prevent causing your circuit to overload again, the first step you need to take is to figure out what circuits power which devices. While this step takes time and is somewhat repetitive, the good thing is, you don’t have to be an expert to accomplish this task. 

The first thing to do is to get a notepad and a pencil and open the door on your main service panel (a.k.a. breaker box). This is the gray metal box, which is usually the size of a cookie sheet that can be typically located in the basement, garage, or utility room. Turn off one at a time the breakers that have a number 15 or 20 stamped on the end of switches.

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After turning off a breaker, walk around the house and try all your lights, other electrical fixtures, and appliances that are plugged in. List down everything that does not have power and which room it is in. You can use a voltage tester to identify if a receptacle has power or not. If you don’t have this device, you can plug in a lamp to see if it’s working or not. 

Note: If you see breakers that are labeled with 30 or other higher numbers, don’t mind them. These are breakers dedicated to supplying appliances that use high-voltage connections such as cooling or heating equipment, electric range or electric ovens, clothes dryers, and water heaters.

When you’re done with an area, go back to your main electric panel and switch on the first breaker. Look for another one that’s labeled with a 15 or 20, then repeat the process until all the circuits that have the said numbers are checked. 

If you had a reliable electrician that previously worked on your electrical system, you may already have labels in your main panel indicating what circuit breaker services what room in your home. This means it isn’t necessary for you to go through your entire home and test each outlet or appliance. However, if you want to be more accurate in your circuit mapping, you can quickly test each area as there could be some devices that are connected to another circuit in your house (e.g. TV in the living room connected to the hallway’s circuit).

Step 2: Calculate Your Circuit Load

Now that you have a circuit map, you can now identify which appliance and fixture are powered by each circuit in your main panel. The next thing to do is to calculate how much these electronic devices are using. When calculating, remember to also factor in plug-in appliances that you don’t move very often. Some examples are an oven toaster or an electric kettle in the kitchen.

To calculate the total load of the electricity you’re using, add the wattage of all the appliances that are connected (or would be plugged in) to a single circuit. 

Note that wattage is the product of volts and amperage: 1 watt = 1 volt x 1 amp

Usually, small appliances have labels indicating their wattage. If a device only indicates amperage, multiply the amp value by 120 (which is the voltage of standard circuits) to get the wattage. 

Wattage = 120 volts x # amps

So for example, a desktop computer uses 1.3 amps, multiply it by 120, this tells you that the device’s wattage is 156.

The circuit breaker that is labeled “15” has a maximum load rating of 1,800 watts, while a “20” breaker has a load rating of 2,400 watts. 

Compare how much total watts you’re using versus the load rating for each circuit. So for example, if a 20-amp circuit already provides power to lights and devices that have a total of 1,300 watts, plugging in a 1,500-watt space heater will surely cause your breaker to trip and shut off the power. 

Step 3: Make changes

Although a 15-amp circuit has a limit of 1,800 watts and a 20-amp circuit of 2,400, for safety, it is strongly recommended to not exceed 80% of the circuit’s maximum rating. So your target should be only 1,440 watts for a 15-amp circuit, and 1,920 for a 20-amp circuit.

If your calculations show that you’re exceeding the limit of a safe load or you’re frequently overloading your circuit, then it’s a clear sign that you should make some changes. We recommend:

  1. Try moving some appliances to a circuit that is not used often (your circuit map will come in handy for this.
  2. Avoid using too many appliances all at once.
  3. Consider switching to LED lights (including holiday lights) as LED bulbs have significantly lower watts compared to incandescent or halogen lights.
  4. Hire a professional electrician to install new circuits in areas where you use plenty of devices (e.g. kitchen or garage workshop).

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Although we provided you here with tips on how you can avoid electrical overload, we highly recommend that you consult with an electrician if you are unsure or have any concerns regarding your electrical system. It is always a better idea to trust a pro than do the guesswork, especially when it comes to anything related to electricity.

Where do I find electricians near me? Locate them here!

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