Professional electricians know circuit breaker mistakes cause electrical dangers. Circuit breaker sizing requires accurate calculations, and the right size is 125% of the circuit’s required ampacity.
Overloaded breakers happen if the circuit breaker is too big. If the circuit breaker is too small, it will trip too often, overheat, or cause an electrical fire. Your appliances and electronics could be destroyed, too.
If you need new circuit breakers, you should hire a licensed electrician. You’ll get the correct size and avoid serious electrical risks. Continue reading this guide and learn how to avoid electrical fires and damaged appliances and pass electrical inspections.
What You’ll Learn:
- You’ll discover how circuit breakers work.
- How to calculate the correct breaker size.
- How different breakers are used in an electrical panel.
- What mistakes you should avoid when buying circuit breakers.
How Circuit Breakers Work
The internal switch in circuit breakers manages the flow of electrical current. The switch trips the breaker if the current limit is reached. Circuit breakers protect your home by shutting down electricity before it overloads the circuits. The following are electrical hazards:
- Circuit overloads: An overload happens if there is too much electricity flowing from the circuit at once. For example, if you plug too many electronics into one outlet.
- Short circuits: A short circuit happens when electricity goes where it shouldn’t. For example, a loose connection lets a live wire touch a neutral wire.
- Ground faults: Ground faults happen when electricity flows in the wrong direction toward a ground. Wet or torn wiring insulation can cause a ground fault.
Each breaker supplies the electrical load according to its amperage. Electricians connect breakers to appliances and systems according to their required electrical load. NEC electrical safety standards dictate requirements for circuit breakers. Our electricians can make sure your breakers and electrical panel meets overcurrent protection requirements.
The Basics of Circuit Breaker Sizing
The basics of circuit breaker sizing is important for all homeowners. This guide helps you understand these concepts to avoid electrical risks and how your circuit breakers work. Here are a few useful terms:
- Amperage: Amperage is the electric current’s strength measured in amps. The amperage is printed on the circuit breakers.
- Voltage: Standard electrical panels offer 120 or 240 voltage. Standard household outlets are 120 volts. Major appliances and HVAC use 240 volts.
- Wire gauge: The gauge of the wiring establishes the electrical current it can carry. The amperage of the circuit breakers must be compatible with the wiring.
Circuit Breaker Sizing Steps
Step 1: Determine Your Appliance Load:
The electricians calculate the appliance load by dividing the watts by the volts. The results show the amps or appliance load. For example, for a 1,200 watt microwave divide 1,200 by 120 volts. The appliance load would be 10 amps.
Step 2: Check the Wire Gauge
Electricians follow the 80% rule when installing breakers. The breaker size and wiring match if the breaker isn’t loaded more than 80% of its capacity. According to this rule, you should never install a larger breaker on the same wire to stop tripping.
Step 3: Factor in Breaker Type
You need both single and double-pole breakers. Your lights and outlets run on single-pole breakers. Most HVAC systems are 240-volt and are connected to double-pole breakers.
The National Electrical Code’s regulations state that you must have a ground fault circuit interrupter. It is installed inside the electric panel. You may also want to install GFCI outlets in kitchens and bathrooms.
Arc fault circuit interrupters are installed on any circuit supplying power in primary living spaces. Your electrician should install AFCIs in living rooms and bedrooms.
Circuit Breaker Sizes and How They’re Used
Circuit breaker sizes establish how they are used. The following are breaker size examples:.
- Outlets and switches use 15-amp breakers.
- Kitchens and bathrooms use 20-amp breakers. They are also used for ground-fault circuit interrupters.
- A dryer uses a 30-amp breaker.
- Ranges and water heaters use 40 to 50-amp breakers.
- Subpanels use breakers that are 60-amp and higher.
Do You Need a Subpanel?
A subpanel is a separate electric panel and connects to the main breaker box. You need a subpanel when you’re setting up electricity services far away from the main panel. A subpanel is also required when you don’t have enough breakers in your electric panel.
Should You Replace Your Own Circuit Breakers?
Licensed electricians know all NEC electrical safety standards. They can make sure your circuit breakers are safe and compliant. Installation mistakes increase electrical fire risks. You shouldn’t install a circuit breaker if you aren’t a trained electrician. Contact Mister Sparky if you need electrical services.
Mister Sparky Can Calculate Circuit Breaker Sizes
Mister Sparky can calculate your circuit breaker sizes. If you need a new circuit breaker, our electricians can make this calculation and replace it. If it’s time to install a new electrical panel or upgrade from an old fuse box we can install it with new breakers.
We’ll make sure all circuit breakers are connected correctly. Our electricians test all breakers and inspect the panel for hazards. We’ll make sure the electrical panel supplies power safely. We may also recommend additional safety equipment like surge protection. Contact Miami’s on-time electrician and schedule an appointment.
Frequently Asked Questions
What breaker does my dryer need?
Standard dryers use a 30-amp breaker
What will happen if the circuit breaker is too small?
There is a greater risk of an electrical fire if your breaker is too small. It can also overheat and trip frequently.
Are all circuit breakers interchangeable?
No, you must use the circuit breakers for your electrical panel brand. You must also use circuit breakers that are the right size.