How to Measure Amps

How to Measure Amps

Learning how to measure amps comes in handy when you are regularly working with electronics. If you should need to put in a new door bell ringer, you might have to do some adjustments with some wiring. You can’t know how much electric current is running through the wire just by looking at it, so you want to make sure that you’re not dealing with wires that have more electrical current than they are rated for.

You can take a trial and error approach, but that could lead to a huge number of setbacks. So, the best way to know which wires are appropriate to mess with is to use a multimeter.

It is the easiest way to measure amps. Don’t worry, these devices are not expensive. They usually cost anywhere between $25-$100. It is also very likely that if you were to look on sites like e-bay or Craigslist, you find them for a little as $10. Get a multimeter and you can test the electric current of all your AC/DC devices.

Before we start, lets cover the basics and terminology

In scientific terms, amperage measures the number of electrons passing through a given point at a given time. In laymen’s terms, amperage is the amount of electrical current running through an electrical component, such as a wire.

Here are the steps to measuring amps

1. You’ll want to make sure there’s no power running through by switching off the breaker. There should be no wetness of any kind near the area you’re working on—not even humidity as it is known to be a cause of electrical shocking incidents. Don’t do this alone. Have the person with you ready with a cell phone in case there’s an emergency. And lastly wear thick rubber gloves.

Before you do any real measuring, you’re going to want to find out what the amperage rating of your multimeter is. If you try to measure electric current with a multimeter that doesn’t have a high enough rating, you could end up damaging your device.

Look for the rating that’s labeled on your device. If it’s not suited for the number of amps that the electrical system you’re measuring is known to have, then you should probably get multimeter with a higher amp rating.

2. Be sure to have your multimeter set at the appropriate function. When you’re measuring amperage, make sure it’s set for AC amperage (for appliances) or DC (for batteries).

3. Remember when we talked about your device having the proper rating? This next step is part of the reason. Set the maximum amperage sensitivity to well above your expected reading. If your device doesn’t show anything when plugged in, then the rating isn’t high. Adjust the sensitivity downward, but not too drastically.

4. Plug the two cords into the terminals. Make sure they’re the right ones. Usually they’re color coded with black plugs and red plugs. If you don’t see any labels, then consult your manual as they should indicate which is which.

5. With this next step, make sure that all your circuit breakers are off and that the device is absolutely turned off. Use an AC current sense probe. Basically, double check that you’re following Step 1. After you’re absolutely sure that everything is off, you will snip the wire. When you do so, make sure that it’s just for your device. Strip back the insulation and attach the wires to the multimeter. Do not touch the stripped wires.

6. Turn the breaker back on. Allow the electrical current to flow for about a minute. If you can’t get a reading, try it again but with the sensitivity adjusted. Do the adjustments somewhat incrementally so you don’t overcharge your device. Whatever your device reads is your measurement for amperage, or amps.

7. To start undoing everything, determine whether the electrical system will be a hazard by double checking that the breaker is back off. Use an AC current sense probe. Give it a moment to make sure there isn’t any electrical current lingering. Undo the wiring to your multimeter device. Switch it off and store it away. Complete the circuit again to get your electrical system back to where it was.

When you do the rewiring, it is better to get new wiring rather than patch it up. Consult a manual if you can. After you’re sure that the wiring is complete, then you can switch the breaker back on.


When taking amp measurements for appliances, it is best to apply the same kind of caution as you would for an electrical circuit. Knowing the amp amounts of your devices and electrical systems can help you make better decisions when it comes time to cutting down on energy use.

Similar Posts

Leave a Reply

Your email address will not be published. Required fields are marked *