Replacing a Circuit Breaker – What Size Should Be Used
How to Replace a Circuit Breaker: Common Mistakes When Replacing Circuit Breakers and How to Avoid Them
Guide to Replacing a Circuit Breaker
Electrical Question: My house was built in 1977 and I have a 14 gauge wire to a bathroom with modern appliances such as hair dryers.
- The circuit is tripping a 15 amp circuit breaker.
- I hired an Electrician who said he “remedied” the problem by replacing the 15 amp circuit breaker with a 20 amp circuit breaker.
- Is this compatible with NEC code?
This electrical wiring question came from: Stephen, a Homeowner from Nantucket, MA.
Additional Comments: Excellent service for the homeowner with limited electrical knowledge.
Thanks for your electrical wiring question Stephen.
Preparations for Replacing a Circuit Breaker
- Skill Level: Advanced – Not recommended for homeowners or non experienced electricians, Best performed by a Licensed Electrical Contractor or Certified Electrician.
- Tools Required: Electricians pouch of hand tools, voltage tester and protective safety gear and arc flash protection.
- Estimated Time: Depends on the make and model of the panel and the condition of the existing electrical circuit breakers and wiring methods.
- Precaution: For safety the main circuit breaker or power source should be turned off and disconnected before replacing a circuit breaker.
- IMPORTANT: Depending on the electrical panel internal components may still be energized when the main breaker is in the off position.
- NOTE: Making changes to electrical panel or electric circuits should with local and national electrical codes, with a permit and be inspected.
Common Mistakes When Replacing Circuit Breakers and How to Avoid Them
- Replacing any circuit breaker with a larger one is extremely dangerous and in violation of the NEC Code.
- Circuit breakers protect the circuit from overloading, therefore replacing any circuit breaker with a larger one can cause the circuit wiring to overheat which can lead to a fire.
- As mentioned in this electrical question, the original 15 amp circuit breaker size was correct. The correct way to remedy the problem of overloading the existing 15 amp circuit is to install a new 20 amp circuit and place the required GFCI protection on the new circuit or install a GFCI outlet in the bathroom.
Selecting the Circuit Breaker Size
- Circuit breakers are sized according to the following electrical circuit factors:
- The type of insulation of the wire or cable that has been installed.
- The gauge of the electrical wire circuit conductor.
- The wire conductor type, which is either copper or aluminum.
- The specifications of electrical equipment that will be powered.
- Once these factors have been determined then the NEC Wire Size Table is used to find the circuit amperage rating which will determine the circuit breaker size.
How to Replace a Circuit Breaker
- Schedule and prepare the occupants and the home to be without electrical power.
- If the project will not be done during daylight then make sure to provide battery powered light sources for home occupants and for yourself.
- When the home and occupants are ready, turn off the main breaker power source to the panel.
- Remove the panel covering from the circuit breakers.
- Turn off the circuit breaker that will be replaced.
- Test the terminal where the circuit wire is attached to the circuit breaker to make sure power the power is off.
- Unfasten and remove the wire that is attached to the circuit breaker wire terminal.
- Circuit breakers are removed by first releasing the opposite end of the wire terminal while hinging it out, and then releasing the wire terminal end and pulling the breaker outward.
- Install the new replacement circuit breaker using the reverse method used for removing the old circuit breaker.
- Make sure the circuit breaker is fully installed.
- Firmly attach the circuit wire to the circuit breaker terminal.
- Prepare to install the panel cover by making sure to clear any interior wiring that may interfere with the panel cover installation.
- Install the cover over the circuit breakers.
- Turn on the main breaker or power source.
- Turn on the new circuit breaker and test the circuit power.
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