How to Replace a 15 Amp Circuit Breaker?

As a diligent homeowner, changing a 15 A circuit breaker is one of the few electrical jobs that can be done legally and easily. The process is simple and quick to carry out, but there are many chances of making mistakes that can be difficult to bear if one does not hire an expert electrical contractor in the process.

The article describes the entire process in considerable detail. It includes the set of toolset necessary for the job, the steps involved in the manipulation of that toolset, and the torque settings required for the job to be done.

To summarise: Shut down the main circuit breaker, check the panel for voltage presence, make a record of the wire configuration, remove the load wire, uninstall the existing equipment from the bus bar and instal an identical 15 A breaker of the same manufacturer and in the same series, make the connections and restore power to the house. Replacing a 15 A breaker for a 20 A is not a valid idea because you will have violated the purpose of the breaker it protects the wire rated for 14 AWG gauge.

Before You Open the Panel

Three checks in this sequence.

• First of all, check whether it’s the breaker. If a breaker trips one time, then it means that it is doing its job. If it trips frequently, it may also indicate a real fault but in this case replacing the breaker will not solve the issue. Getting faults correctly means diagnosing the problem properly first.
• Next, find out the panel type. The label on the inside of the door specifies the type of panel as well as which devices are compatible with it. It is important to note that breakers are not interchangeable across brands. Using a breaker which does not fit the bus represents a fire hazard and does not solve the problem.
• Make sure you obtain the necessary part. 15 A, single-pole, same series, interrupting rating. A standard device is a commodity item, and the range is visible in this single-pole MCB specification. Buy one spare while you are at it; the trip to the shop costs more than the device.

Tools

Use insulated screwdrivers that have a square drive for terminal screws, torque screwdrivers, and two pole voltage testers instead of using neon screwdrivers. A phone is needed for pictures, and a head torch is needed because panels are dark and live parts are not forgiving.

The tool that many homeowners do not use and is the best for determining whether a new breaker can last for 25 years or only 5 is the torque tool. Loose terminations are the main culprit of breaker failure even though they are done manually each day.

Step by Step

• Let all house occupants know that the power is going off before anything else. Remove power from all computers.
• Switch off the main circuit breaker. Depending on the main box’s design, the main breaker may be located at either the top or the bottom of the box.
• Make sure that the breaker is dead. Take the voltage reading of the wires connected to the main breaker. If neither displays any voltage, it means that the circuit breaker is switched off or that you might have connected to the wrong panel.
• Record how the wiring is connected, take a picture of the position of the breaker, and note down the breakers specifications.
• Disconnect the wire from the load terminal.
• Remove the old device to install the new one. Push it from the bus end. In case it is still stuck, remove the retention screw if the panel uses one.
• Put the new device on the bus and wait for it to click in place. If it has a retention screw, put it in place.
• Reconnect the wire to the load terminal as shown in the instruction book and do torqueing according to the circuit breaker or the panel’s specifications.
• Make sure that the wire does not move after you pull it lightly.
• Switch on the main breaker and conduct the testing of the circuit from the farthest socket.
• Update the panel information record including the date of the installation.

The photograph in step four has saved the majority of the jobs done. People put so much effort into wiring the panel so it would be better to copy it than create a new wiring scheme.

Torque, Strip Length and the Details That Matter

Every piece of equipment will have its torque specification indicated, which will usually fall between 1.5 and 2.5 N·m for a miniature circuit breaker terminal. Insufficient torque results in the development of heat; while excessive torque will lead to damage to the conductor and terminal. In both instances the failures will occur after several months.

Strip length is an important aspect that is oftentimes underestimated. If the strip is too short, the conductor ends up resting on the insulation of the terminal, which creates a joint with high resistance. If the strip is too long, then the copper conductor sticks out the terminal, which creates clearance problems. The majority of devices have their required strip length molded into the device case positioned right next to the terminal.

If the conductor is made of aluminum, it is crucial to check whether the equipment is suitable for use with aluminum, whether or not an antioxidant compound is needed, and also if the device is rated for the task. Using a copper-type device with the aluminum branch conductor is a well-known way of causing devices failure, which is one of the reasons why aluminum branch wiring that was made in the 1960s-1970s enjoyed a very bad reputation.

Where a device needs to be identified from its markings rather than its box, the technical download library carries the dimension drawings and torque tables for the KNB and KNL ranges.

The Upgrade You Must Not Make

If the breaker prevents functioning because of circuit excess load, the first thought is to use a 20A transformer. But one should not take this approach.

A 15 A breaker was made for the 14 AWG copper wire which has a capacity of 15 A. By using a 20 A breaker, the amount of current that can go through the wires is increased until the moment of breakdown, making the wire itself act as a fuse, which realization comes when the break is not visible until the fire occurs.

There is one more limit that is less evident. 15 A circuits are usually equipped with 15 A sockets which have also a 15 A capacity. 20 A circuits may have either 20 A sockets or T devices along with 12 AWG wires. The breaker itself is the cheapest part of this upgrade but it is also the most hazardous to change.

The proper solutions to the situation with 15 A circuit tripping are: to transfer some load to the other circuit, to install a separate circuit, or to fix or change the faulty device.All three cost more than a breaker and less than a fire, and the calculation for each is set out in our branch circuit FAQ.

When the New Breaker Trips Immediately

Three things to check, in order.

• The circuit is faulty. Any short or ground fault taking place downstream will cause the good breaker to trip as soon as possible. Unplug all loads on the circuit and try again. If the circuit stays on, then it’s a load fault; if not, the fault is in the wiring.
• The device is wrong. A B-curve device on a motor load always trips the moment it starts to run. A device with the wrong rating trips too early. Compare curves and ampere ratings for the old and the new devices; that’s where the photo is of great help.
• An explanation, albeit rare. But these occurrences do happen, more often when buying cheap stuff online. Buy from a distributor who will take it back, and check that the interrupting capacity is as marked: a 10 kA single-pole device is what a modern residential board expects, and a copy with 3 kA inside the same case is a common fake.

If an alternative appliance trips in the same spot where the old appliance failed, that means the problem does not originate in the breaker. Such situations are very common when the appliance is replaced by its owner with a new one, which is why it is important to check the circuit before purchasing an appliance.

When to Stop and Call

Four circumstances are not DIY.

The panel is a Federal Pacific Stab-Lok, Zinsco, or Pushmatic since these have known failure-to-trip records, which means there’s a panel instead of a circuit breaker. The bus has corrosion, discoloration, or arc markings where the previous equipment was. The main breaker is not able to turn off, or the panel cannot be de-energized. The conductor is made of aluminum, or the insulation cracks and crumbles as soon as it is touched.

Each condition mentioned in this scenario makes a fifteen-minute work into a major task, and each can be easily observed even before starting to work on it. Where the answer is not obvious from the panel, our technical service team will identify the panel series and the correct device from photographs.

FAQ

What is the price of replacing a 15 amp breaker?

The cost of the breaker ranges between $5 and $15 and the installation cost falls between $150 and $300. A DIY installation only requires the purchase of the breaker and the use of a torque screwdriver.

How can you tell that the 15 amp breaker is faulty?

There is no resetting of the breaker, the breaker nips even after removal of load, the breaker is too hot or discolored, there’s burning smell nearby, or the switch is not firmly attached. Any of these conditions is sufficient evidence for replacement.

Is self-replacement of a circuit breaker possible?

Yes, if the circuit breaker was replaced with a similar breaker and done by someone competent; however, certain jurisdictions require users to hire a licensed electrician for installing circuit breakers. Nobody should try DIY for the electric panel components or for that of the service.

Is replacing a 15-amp breaker with a 20-amp breaker okay?

It is inadvisable because a 15-amp breaker protects conductors rated at 15 amps. A 20-amp breaker on that wire does not offer that protection, causing safety hazards, and because the receptacles for that circuit are usually rated at 15 amps.

References

• NEMA — Circuit Breaker Installation and Torque Guidance
• Cerrowire — 14 AWG Ampacity and 15 A Circuits
• This Old House — Replacing a Breaker Safely
• Bob Vila — Circuit Breaker Replacement Steps
• U.S. Department of Energy — Home Electrical Safety Basics

Conclusion

The job of properly identifying ratings according to the electric appliance series, confirming wattage, and supplying details about the malfunctioning equipment has been done. It’s that simple, one change of a 20 amp device can save you from possibly ruining something.

Should you have any doubt about which one to buy, simply take a picture of your currently used device and its label and send it to us.