How to Avoid Overloading Electrical Circuits
January 19, 2018
There are many reasons why your circuit breaker or fuse box may overload and cut off power to the circuit.
For instance, electrical panels in older homes may not be sufficient for the energy demand of modern appliances and electronics.
Overloading your electrical circuits and tripping the circuit breaker or blowing a fuse is normal, but not if it happens repeatedly. If you are experiencing a frequently tripping breaker, speak with a professional electrician to see if any faulty wiring, inadequate power, or other conditions exist.
Sometimes, if you have an old or aging electrical panel, there may not be enough room for additional circuit breakers and wiring. Your electrician will be able to tell if you have unsafe electrical conditions, including whether the sizes of the wires are compatible with your breaker panel.
Still, the number one reason for tripped breakers and blown fuses is overloading the circuit breaker.
How to Avoid Overloading Electrical Circuits
Often, the cause of an overloaded circuit is the use of too many lamps and electrical devices on the same circuit at the same time.
It’s possible to balance the power load by plugging one of your high-use appliances into a different circuit. But don’t try to get around overloading your circuits by stringing multiple-extension cords together. This is a fire hazard! Extension cords are for temporary use only. If switching circuits doesn’t solve the issue, faulty wiring may be the problem.
To be sure of how many devices you can plug into your circuits at one time, carry out wattage calculations as described below.
National Electrical Code (NEC) Requirements (Dedicated Circuits)
Keep in mind that large appliances, such as refrigerators, HVAC systems, and dryers all require their own “dedicated circuit.” This means that all of your large 240-volt appliances need to have their own circuit, with a separate fuse or breaker.
When you disconnect the fuse or breaker, it should only disconnect one appliance. If you suspect illegal cable running, which tries to bypass the panel’s power limitation, contact an electrician as soon as you can.
Estimating Power Requirements (Wattage Calculations)
Label Your Circuits
If the circuits in your electrical panel are not labeled, do so now. Have a partner help you determine which circuit is connected to which area of the home by taking turns turning off each individual breaker. The circuit that turns off is the circuit the breaker is connected to.
As mentioned before, some of your circuits should 240-volt “dedicated” circuits.
Convert Your Breakers to Wattage
To figure out how many devices you can plug in, first determine how much the circuits in your panel can handle. You can usually tell how much power the circuits can handle by multiplying the amperage rating (20 or 30-amp) by 120 (volts) to figure out the total wattage capacity. Open up your electrical panel to learn how many amps each circuit can safely handle.
Wattage = Amperage Rating x 120 (Volts)
For example, the maximum allowed wattage of a 15-amp circuit at 120 volts is 1,800 watts. If you have 20-amp circuits at 120 volts, it would be 2,400.
Multiply Circuit Wattage Capacity by .8 (80%)
While it’s possible that your circuit can handle more than 80% of its power rating, it is likely that once you exceed 80% of its maximum rating, the breaker will trip.
We recommend not exceeding 80% of the circuit’s maximum allowed wattage.
Wattage = Amperage Rating x 120 (Volts) x .8
For example, the recommended wattage of a 15-amp circuit at 120 volts is 1440 watts (80% of 1,800).
Compare Allowed Wattage with All Plugged-In Devices
Compare the amount of power your circuits can handle with the wattage or amperage rating of each device and fixture (check rating plates, tags, and packaging).
For a guide, here are some common electrical devices along with their required wattage (actual wattage should be verified per device):
- Blender (500-1,000 watts)
- Hair dryer (600-1,200 watts)
- Radio (5-50 watts)
- Television (200-500 watts)
- Vacuum Cleaner (250-1,200 watts)
- Light Bulb (20-250 watts)
Once you have added up all of the light bulbs and plugged-in devices, you can see if they are cumulatively overloading the circuit.
Is One Appliance to Blame?
Sometimes, when a large energy-consuming appliances switches on, the breaker trips. If one particular appliance is to blame, contact an electrician or appliance repair person.
During the winter months, a common culprit is an electric space heater. Many space heaters use over 1500 watts, nearly maximizing your circuit’s allowed wattage. Space heaters are much more expensive than central heating. If you do use a space heater, turn the thermostat down and make safety your number one priority. For instance, always plug the space heater directly into an outlet (not an extension cord)!
Replacing Fuses (Warning!)
If you have a fuse box, make sure you have an electrician check their capacity. All of your fuses should match the capacity of the circuit. Either on purpose or by mistake, many people replace their fuses with one with a higher rating. This can cause too much current to pass through the fires, possibly leading to overheating and an electrical fire.
Overloading Extension Cords (Warning!)
If you are trying to bypass tripping a circuit, you may think an extension cord would provide an easy fix. Extension cords, however, should only be used as a temporary solution. Extension cords can provide temporary circuit relief, but do not use them for the long-term. Follow the extension cord’s manufacturer information and these extension cord safety tips.
If your circuits continue to blow and you need more power, contact an electrician to install new circuits, outlets, and electrical panels.
Learn more electrical safety tips for your home.
It’s important to take care of electrical panel problems before they turn into electrical hazards. If you notice any melting plastic, burning, corrosion, or any other damage to your panel, contact a qualified electrician right away.
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