Why Does My Miter Saw Keeps Tripping The Breaker?

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My house is 130 years old, and the “cellar” is a dirt floor with original stone walls.  I’m 6’1″, and have to stay low as there is only about 5 feet of space height.

After tripping a breaker as I added appliances in the kitchen and laundry room too many times, I had the electrical panel replaced.

Key Points:

  • The cause could be a faulty standard breaker, a faulty electrical panel, or a faulty motor on the saw.  It can get technical, but one of those three is likely a contributing factor.
  • If your saw has a brushed motor, the brushes might be worn and in need of replacement to cure the problem.
  • A soft start adapter will help your saw start up with a gradually increasing power flow that can keep the breaker from tripping.

I got tired of having to go down those steps and hunch over to get to the panel.  Since the new panel was installed, there have been no further breaker incidents.  Had I not done that, my miter saw and/or table saw could have been added to the list of appliances and power tools that tripped the old panel breakers.

But, if your panel isn’t that old, is up to code, and your miter saw is tripping your breaker, something else is at play.  What might it be?

What Are Some Of The Potential Causes of a Tripped Circuit Breaker?

You turn on your miter saw, and it immediately trips the circuit breaker.  How frustrating that can be, of course.

There are a few reasons why your saw might be tripping the breaker. Here are some of the most common causes:

  • The miter saw is drawing too much current. Miter saws can draw a lot of current, especially when they are first turned on. If the circuit breaker is not rated for the miter saw’s full load current, it will trip.
  • There is a short circuit in the saw. A short circuit is a condition where electricity flows through a path that it is not supposed to flow through. This can cause the breaker to trip to protect the circuit from damage.
  • The breaker is faulty. It is possible that the breaker itself is faulty and is tripping even though there is no problem with the miter saw.
  • The saw is plugged into a shared circuit with other appliances. If the miter saw is plugged into a circuit that is also powering other appliances, the total current draw on the circuit could be too high, which could cause the breaker to trip.

To troubleshoot the problem, you can try the following:

  • Check the saw’s power cord and plug for any damage. If the power cord or plug is damaged, it could be causing a short circuit.
  • Plug the saw into a different receptacle outlet on a different circuit. If the miter saw does not trip the breaker on a different circuit, then the problem is likely with the original circuit.
  • Have an electrician inspect the saw. If you have checked all of the above, and the saw is still tripping the breaker, it is possible that there is a problem with the saw itself. An electrician can inspect the saw and determine if it is safe to use.

Here are some tips to prevent the breaker from tripping in the future:

  • Make sure that the saw is plugged into a circuit that is rated for its full load current. The current rating is usually listed on the saw and is certainly in the documentation that came with the saw.
  • Do not overload the circuit. If you are using other appliances on the same circuit, make sure that the total current draw is not too high.
  • Inspect the power cord and plug regularly for any damage. If the power cord or plug is damaged, replace it immediately.
  • Have an electrician inspect the miter saw periodically. An electrician can inspect the miter saw for any signs of wear or damage and make sure that it is safe to use.

Miter Saw Tripping Breaker on Startup

Electrical Panel

If your miter saw keeps tripping a breaker on startup, it could very well be the saw more so than the breaker.  Let us explain.

Worn brushers in your miter saw may be contributing to the problem.  If your miter saw is a brushed motor, not a brushless motor, you should suspect worn brushers as contributing to the problem.

Worn Brushes Causing Breaker Tripping

Brushed and brushless motors are both types of DC motors. They both convert electric current into rotational motion. The main difference between the two is that brushed motors are mechanically driven while brushless motors are electronically driven.

Brushless motors are more energy efficient and can run for up to 50% longer on battery power than brushed motors. They also have less friction, which means they can reach higher speeds and have more power and torque. However, brushless motors are more expensive and require specialized knowledge and equipment for repair and maintenance.

Because brushed electric motors are mechanically driven, driven by the brushes, when they become worn, they cause more friction, and the motor will require added “juice” to get started.

Worn brushes in a miter saw can increase startup amps. The brushes are responsible for transferring electricity from the motor to the spinning saw blade. As the brushes wear down, they become less effective at transferring electricity, which can cause the motor to draw more current.

This can lead to the breaker tripping, especially when the saw is first turned on, more so than the continuous load once the saw is up and running.

In addition to increasing startup amps, worn brushes can also cause other problems with the miter saw, such as:

  • Reduced power
  • Intermittent operation
  • Stalling
  • Burning smells

If you notice any of these problems with your miter saw, it is a good idea to replace the brushes. This is a relatively easy and inexpensive repair that can save you a lot of trouble in the long run.

Here are some very general tips for replacing the brushes in your miter saw:

  • Make sure to purchase the correct replacement brushes for your saw.
  • Turn off the saw and disconnect it from the power source before you begin.
  • Use a small screwdriver to remove the old brushes.
  • Clean the brush holders before installing the new brushes.
  • Apply a small amount of grease to the new brushes.
  • Install the new brushes and secure them with the screws.
  • Reconnect the saw to the power source and turn it on.

If you are not comfortable replacing the brushes yourself, you can take the saw to a qualified technician.

What Is A Soft Start Adapter And Can It Help Prevent Tripping Breaker?

A soft start adapter is a device that is used to reduce the inrush current of an electrical appliance, such as a power tool. Inrush current is the large surge of current that a power tool draws when it is first turned on. This surge of current can be harmful to the tool and can also overload the circuit breaker.

A soft start adapter works by gradually increasing the voltage to the appliance over a period of time. This allows the tool to start up without drawing a large surge of current. Soft start adapters are typically used with appliances that have a large motor, such as air conditioners, refrigerators, and power tools.

Soft start adapters have a number of benefits, including:

  • They can help to protect power tools from damage caused by inrush current.
  • They can help to prevent circuit breakers from tripping.
  • They can help to extend the lifespan of power tools.

Soft start adapters are relatively inexpensive and easy to install. They can be purchased from most electrical retailers.

Here are some of the benefits of using a soft start adapter:

  • Reduces inrush current: A soft start adapter gradually increases the voltage to a power tool (miter saw, table saw, etc.), which reduces the inrush current. This can help to protect the tool from damage and prevent circuit breakers from tripping.
  • Extends the lifespan of power tools: Inrush current can cause wear and tear on appliances, so reducing inrush current can help to extend the lifespan of appliances.
  • Makes it easier to start power tools: Some appliances can be difficult to start. A soft start adapter can make it easier to start them by reducing the inrush current.

If you are considering using a soft start adapter, there are a few things you should keep in mind:

  • Make sure the adapter is compatible with your tool: Not all soft start adapters are compatible with all tools. Make sure to check the compatibility before you purchase an adapter.
  • Size the adapter correctly: The size of the soft start adapter is important. If the adapter is too small, it will not be effective in reducing inrush current. If the adapter is too large, it could overload the circuit.
  • Install the adapter correctly: It is important to install the soft start adapter correctly. If the adapter is not installed correctly, it could be ineffective or even dangerous.

Overall, soft start adapters can be a helpful way to reduce inrush current and protect tools from damage. If you are considering using a soft start adapter, be sure to do your research and choose an adapter that is compatible with your power tool and is sized correctly.

Inductive Loads Causing Breakers To Be Tripped

Inductive loads are electrical loads that create a magnetic field when current flows through them. This magnetic field opposes the change in current, which creates a delay between the voltage and current waveforms. This delay is called inductive reactance.

Inductive loads are common in many electrical devices, including induction motors, transformers, and chokes. They are also found in some lighting fixtures, such as fluorescent lights.

Inductive loads have a number of characteristics that distinguish them from other types of loads. These characteristics include:

  • Current lags voltage: The current waveform in an inductive load lags behind the voltage waveform. This is because the magnetic field needs time to build up before it can oppose the change in current.
  • Reactive power: Inductive loads consume reactive power. Reactive power is the power that is used to create the magnetic field. It does not do any work, but it does contribute to the overall power consumption of the load.
  • Power factor: The power factor of an inductive load is typically less than 1. Power factor is a measure of how efficiently a load converts electrical energy into useful work. A power factor of 1 indicates that the load is converting all of the electrical energy into useful work. A power factor of less than 1 indicates that the load is consuming some of the electrical energy as reactive power.

Inductive loads can have a number of effects on electrical systems. These effects include:

  • Increased current draw: Inductive loads can increase the current draw on an electrical system. This can overload the system and cause problems such as circuit breakers tripping.
  • Reduced power factor: Inductive loads can reduce the power factor of an electrical system. This can lead to increased losses in the system and higher electricity bills.
  • Harmonics: Inductive loads can generate harmonics, which are unwanted frequencies that can interfere with other electrical devices.

There are a number of ways to mitigate the effects of inductive loads on electrical systems. These methods include:

  • Using capacitors: Capacitors can be used to compensate for the reactive power consumed by inductive loads. This can improve the power factor of the system and reduce the current draw.
  • Using soft start: Soft start devices can be used to reduce the inrush current of inductive loads. This can help to protect the system from overloads.
  • Using power factor correction: Power factor correction devices can be used to improve the power factor of a system. This can reduce losses in the system and lower electricity bills.

Inductive loads are an important part of many electrical systems. By understanding the characteristics of inductive loads and the effects they can have on electrical systems, you can help to ensure that your systems operate efficiently and safely and breakers are not tripped.

This ties back into the startup of your power tool as tripping a breaker.  The startup can call for more power, as we have said, and a soft start adapter for your saw can mitigate inductive load effects on the electrical loop between your saw, the wall receptacle outlet, the circuit breaker, and the electrical panel.

A bit technical, yes, but it does lead to a basic understanding of what is in play when your saw keeps tripping the breaker.

Let’s keep the cause and solutions simple:

  • Check the outlet and saw cord. Perhaps a dedicated circuit just for your shop’s power tools should be considered rather than sharing a circuit with your refrigerator, stove, washer, dryer, etc;
  • Make sure the breaker is rated for saw’s electrical power needs;
  • Check the brushes in your saw’s motor if it is a brushed motor;
  • Replace worn brushes;
  • Use a soft start adapter.

Something(s) on this list can cure the problem.  My power tools have their own circuit, so I don’t have to go down those steps anymore.  Thank goodness.

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