Circuit breakers are one of the most important components in your home’s electrical system and are a vital safety mechanism used in all modern electrical systems. The primary purpose of a circuit breaker is to prevent electrical fires and damage that can occur if too much current flows through an individual circuit. A circuit breaker also helps to protect any appliances hard-wired to the circuit or plugged into an outlet on the circuit since these things can also be damaged if the circuit gets overloaded. In this article, we’ll explain how circuit breakers work, the different types of circuit breakers and why they are so important.
Why Circuit Breakers Are Important
Electrical overloads can occur for a variety of reasons such as short circuits caused by a frayed wire or a loose electrical connection. These issues can lead to the current arcing or jumping from the hot wire across to the neutral wire. When this happens, the electricity can flow unimpeded, leading to a massive spike in the current flowing through the circuit. An overload can also occur because of a sudden power surge or simply because too many things are plugged in and trying to draw more power than the circuit was designed to supply.
An overloaded circuit is a serious safety hazard. When too much current flows through a circuit’s wiring, it causes the wires to start overheating quickly. This can result in the shielding or insulation around the wires melting and possibly catching fire. If the current arcs or sparks, it can also easily start a fire.
How Circuit Breakers Work
To understand how circuit breakers work, you first need to know the basics of how an electrical circuit is set up and works. Electrical circuits are closed loops. Electricity flows out of the electrical panel into a circuit through the hot wire that supplies all of the “loads,” which are all the electrical devices plugged into or hard-wired to the circuit. All of the current then continually flows back to the electrical panel through the neutral wire.
Before flowing out into the circuit’s wiring, the current first passes through the circuit breaker. Inside a circuit breaker is a metallic bi-strip, an electromagnetic copper coil, a moving contactor and a stationary contactor. The current first flows through the bi-strip and into the copper coil before flowing through the two contactors and out into the circuit. If the circuit overheats or experiences a short circuit, a switch triggers that causes the moving contactor to drop down. This breaks the connection between it and the stationary contactor, which opens the loop and breaks the circuit so that electricity can’t continue to flow.
The metallic bi-strip provides thermal protection, which means it will trip the breaker if the current rises to the point that the circuit starts overheating. If the bi-strip gets too hot, it will bend and move the switch so that the contactors no longer touch, and the circuit instantly breaks.
The copper coil provides electromagnetic protection against short circuits. When electricity flows through a copper coil, it produces an electromagnetic force. The greater the current flowing through the copper coil, the stronger the electromagnetic force it produces. When the current flowing through the coil rises above a safe level, the electromagnetic force becomes strong enough that it moves a spool inside the coil. When the spool moves, it also triggers the switch and shifts the moving contactor away from the stationary contactor so that the circuit breaks.
When you reset a circuit breaker after it trips, the switch shifts the moving contactor back up so that it touches the stationary contactor. This reconnects the circuit or closes the loop so that electricity can again flow.
Different Types of Circuit Breakers
There are four primary types of circuit breakers: standard, GFCI, AFCI and dual GCFI/AFCI. Standard breakers only provide protection against overheating and short circuits. GFCI (Ground-Fault Circuit Interrupter) breakers protect against the risk of electrocution that can result from a ground fault. AFCI (Arc-Fault Circuit Interrupter) breakers prevent a fire outbreak that can occur when there is an arc fault, which is when the current starts arcing or sparking out of a wire.
A ground fault is when the current flows through an unintended path and into any nearby grounded surface or object. If a damaged wire, frayed power cord, or moisture comes into contact with an outlet or wire, the current can flow out of the circuit and energize anything nearby. For instance, if the cord on your toaster is damaged, the current can flow into and energize the outer metal part of the toaster. If you were to touch the toaster, your body would become the unintended path, and you would essentially become part of the circuit. This means that the current would instantly start flowing through you, and you’d get electrocuted.
GFCI circuit breakers and outlets prevent this issue by detecting if the current leaks into a grounded object. These circuit breakers and outlets work by monitoring the current flowing in through the hot wire and back out through the neutral wire. When everything is working as it should, these two currents should be balanced. If there is an imbalance, it indicates that the current is flowing out of the circuit into an unintended path, such as a person. If the GFCI detects an imbalance, it will instantly trip so that the current stops flowing.
All it takes is around 10 milliamps of electricity flowing through a person for two seconds for them to get electrocuted. GFCIs are extremely sensitive and will trip if they detect between 4 and 6 milliamps of leakage. They also trip and break the circuit in less than one-tenth of a second. These two factors combined ensure that there is almost no chance of electrocution if a ground fault occurs.
AFCI circuit breakers work by monitoring the circuit to “listen” for the telltale signs that occur when the current sparks or arcs out of the wires. Alternating current produces sound at a specific frequency, and the current also produces a specific frequency when it arcs. If the AFCI breaker detects this arcing frequency for more than a few milliseconds, it will immediately trip. Arcing usually occurs because the circuit has a damaged wire or loose connection that allows the current to jump, which can easily catch any combustible objects nearby on fire.
Although AFCI circuit breakers are designed to prevent arc faults, they will also trip if there is an overload or short circuit just like a standard circuit breaker. The same is also true for GFCI breakers. However, a GFCI breaker can’t detect arc faults, and an AFCI breaker can’t detect ground faults or leakage. This is why there’re dual GFCI/AFCI breakers that can detect both types of faults and also protect against overloads, overheating and short-circuiting.
GFCI circuit breakers or outlets are required for all circuits or outlets that could be exposed to moisture or where there may be damaged cords or wires. This includes kitchens, bathrooms, basements, laundry rooms, garages and outdoor circuits. Some local electrical codes require AFCI protection for the majority of circuits in the home, but other places only require AFCI breakers for bedroom circuits.
If you’re experiencing any issues with your electrical system, the expert electricians at Absolute Electric are ready to help. We specialize in all types of electrical repairs and installation and can also perform an inspection to ensure your electrical system is safe. For more information on the range of electrical services we offer in Sterling, give Absolute Electric a call today.