If you live in an older home, you may not have enough outlets to power your 21st-century lifestyle with all its electronic devices and designer appliances. If your solution is to equip the outlets you do have with power strips so you can plug in more devices, you're risking a blown outlet or worse. An overloaded outlet, which is one with more current running through it than it can handle, can get hot enough to melt and expose wires, which can short together and start a fire.
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One solution is to add more outlets, but you can't do that if the circuit is overloaded. If you pass enough current through the brand-new outlets to overload the circuit breaker, you'll be constantly running to the breaker box to reset it. If you want to add more outlets, which is a great idea, you may have to install a new circuit controlled by a brand-new breaker.
Electrical Overload Definition
An electrical overload isn't a matter of exceeding the voltage in the circuit, which is actually impossible. All residential outlets run on 120- or 240-volt power and those numbers are determined by transformers on the power line. You overload a circuit breaker when you pass too much current through the circuit, whether it's through a single outlet or several.
Most residential circuits are rated for 15 amps, but heavy-duty ones, such as the ones in the laundry room or garage, are rated for 20 amps. If you exceed an outlet's current rating, you've overloaded it, but how do you know? You can tell by reading the current draw from the label of each of the appliances you're using and adding those numbers together.
When the Breaker Trips
The breaker controlling the circuit for an array of 15-amp outlets is also rated for 15 amps, so if you overload a particular outlet, the effect is the same as overloading the circuit in general: the breaker trips. The outlet stops working, but it's because the breaker has tripped, not necessarily because the outlet isn't working anymore. You can restore power to the outlet by resetting the breaker.
A small lag occurs between an overload and the breaker response, however, and if the overload is extreme, as in the case of a power surge, the current can generate enough heat to melt the outlet. If an overloaded outlet is damaged in any way, don't restore power until you replace the outlet. You can't repair a melted outlet, and if you try to use it, it could cause arcing, which can injure you and start a fire.
What If the Overloaded Outlet is a GFCI?
Most homes have at least one GFCI outlet because the electrical code now requires them in certain areas of the house. The acronym stands for Ground Fault Circuit Interrupter, and the purpose of the outlet is to shut off power when a circuit anomaly known as a ground fault occurs. A ground fault isn't the same thing as circuit overload, but a GFCI does also offer electrical overload protection.
A GFCI outlet has a reset button, and when the outlet trips, you restore power by pressing it. If the outlet trips again, something in the circuit is triggering it, so unplug everything from the outlets on the circuit and try again. If it stays on, plug in all the appliances one by one until you come to a faulty one.
A GFCI outlet responds to faults in all outlets wired in the circuit after it, so if a particular conventional outlet isn't working, and the breaker hasn't tripped, look for a tripped GFCI somewhere in the circuit. It can be in another room or even outside, depending on how your house is wired.
Chris Deziel is a contractor, builder and general fix-it pro who has been active in the construction trades for 40 years. He has degrees in science and humanities and years of teaching experience. An avid craftsman and musician, Deziel began writing on home improvement topics in 2010. He worked as an expert consultant with eHow Now and Pro Referral -- a Home Depot site. A DIYer by nature, Deziel regularly shares tips and tricks for a better home and garden at Hunker and Family Handyman.