how to check amp draw on a motor

How to Check Amp Draw on a Motor? [AC Motor]


Sometimes you need to check the amperage when working on an electrical project. Checking amps can help you figure out whether something is sapping extra power. So, taking an amperage reading can be helpful.

But how to check amp draw on a motor?

First, check the amperage draw that your motor needs. Then prepare your multimeter to get amps. Then run the motor and find the positive and negative terminals. Next, connect the metal sensor on the red and black wires from your multimeter to the positive and negative terminals. Lastly, check the display of the multimeter and remove the sensors.

This isn’t enough. That’s why we have brought together a step-by-step process.

So, let’s get started!

What Kind of Tools Do You Need to Conduct the Test?

Almost all have an electrical multimeter in our toolbox. We need it for checking electrical properties. For example, you can check your brushless motor with a multimeter

The AC Amperage setting on these meters permits testing of a wide range. From $60 to $500, you can get an electrical meter. 

You can purchase from one of these. So check down below-


One end of the meter has what seems to be two fingers. That wraps around the wire to be tested. This feature is found on some meters.

Most small systems use a wire clamped in the blower compartment to measure ampacity. Then you need to close the compartment door while the test is running.

A tiny amp clamp on the end of a 3- to 4-foot line is a requirement. It’ll access the chamber. Resemble a clothespin with two insulated wires attached to the meter. 

This clamp attaches to the motor’s power cable. That measures the current being drawn by the motor.

For knowing the full process you need to go for step-by-step procedures. Here it is below-

How to Check Amp Draw on Your AC Motor? [Step-by-Step]

Now, let’s come to the important part. We hope you have your multimeter with you. Also, the steps might not be exactly similar to that of DC motors. Because both AC and DC motors have significant differences

If you’re ready, let’s check out the easy steps for checking the draw on the AC motor-

Step 1: Read the Amps Draw the Motor Needs 

Before you start anything, you need to know the amps draw your AC motor requires. You also need to see if the motor is operating properly. 

You can check the label on your AC motor to know the accurate amps number. It should be there. 

Step 2: Prepare the Multimeter

Now, set your multimeter to the proper amps range for the AC motor you’re checking. For instance, if your motor draws about 20 amps, set your multimeter to the amps range of 10-30. 

Step 3: Find the Motor Terminals 

Now, run the motor to check the amps draw. Then figure out where the terminals of your AC motor are. 

Well, it’s quite simple to locate them. Because the terminal that’s positive is marked as a plus (+) and the negative one is labeled as minus (-). 

Step 4: Connect the Multimeter to the Motor

Make sure you’re wearing protective gloves before performing this task. Otherwise, you can get an electric shock. You can use the same gloves used for soldering xt60 connectors

Now, there are two wires coming from the multimeter. Both wires have metal sensors in the end of them. 

These should be placed on the motor terminals. The metal sensor on the red wire has to be placed on your motor’s positive terminal. Then place  the black wire’s metal sensor on to the negative terminal. 

Note, you should be super careful while performing this step. Make sure to not touch any moving parts while connecting the sensors with the terminals. 

Step 5: Read the Display of the Multimeter

It’s time to check the multimeter’s display. The reading should be within your set range on the multimeter. Only then you can be sure that the correct amps are being drawn from the motor. 

But if it’s below the proper range, you have to get your motor checked by a professional. Because this indicates that your motor has problems. 

For example, you might have to get new brushes. While you’re at it, get the best ones. Just you’d get the top-performing NIMH batteries for your rc car

Also, don’t worry, the motor won’t draw more amps than the set range. Because that’s just impossible. 


Question: What should I check with the multimeter if electricity is flowing to the circuit breaker?

Answer: To do so, you would have to remove the breaker panel cover. That is something you should only undertake if you have prior experience with it. If other parts of the house have power, assume the breaker does too.

Question: How can I determine a battery’s amp draw?

Answer: To begin, remove the positive battery cable from the battery. After that, attach the meter probes to the wire. Also, attach the battery post to complete the circuit. To learn more, return to the article and read it from beginning to end.

Question: When using a multimeter to measure amperage, should I use “AC” or “DC”?

Answer: Most home equipment is presumably powered by AC electricity. If the electricity is converted to DC via a transformer, use the DC option. Thus, verify the voltage label to be sure.


That’s was everything on how to check amp draw on a motor. Hopefully, you don’t have to stress about drawing amps from AC motors anymore. Just do it by following the steps mentioned above.

Good Luck!

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