How to Use a Clamp Ammeter

What You'll Need
Clamp Ammeter
What You'll Need
Clamp Ammeter

When you are having problems within your alternating current, a clamp on ammeter is a great tool to help you troubleshoot and pinpoint the problem. There are many types of different devices on the market today that can help you with troubleshooting different types of electrical problems. The clamp on ammeter is one that has a specific job so there is less of a learning curve than the more involved multimeters. 

Step 1: Determine Current Draw

Before you can read the current on the AC device you will need to know what the current draw is of the item. This is usually found on the tag that accompanies the device. It will be located on either the power cord or where the basic power information of the AC device is listed. 

Step 2: Find Power Wire

Every AC device is going to have a wire that is feeding a current to the working part of the item. This wire is going to be found in either the circuitry of the item or within the main electrical wiring makeup. It is usually going to be red in color. For some items, this will mean taking off the back panel to access the wiring components. On some larger items, like appliances, there will be a small access panel.

Step 3: Set Ammeter

Turn on your ammeter and dial in the item's amperage draw that you are going to check. For example, if the item is going to draw 10 amps, you will want to dial this into the ammeter. Once this number is set you will be able to determine if the item is drawing the amount of current that it needs.

Step 4: Place Clamp on Wire

Using your thumb to open the jaws of the clamp you will need to place it on the power wire. Once the clamp in on the wire that you are going to be testing, it must be closed fully and locked into position. Make sure that the jaws of the clamp have a good purchase of the wire and is properly seated. If not, the ammeter will not be able to receive a good reading of the current that the item is drawing. 

Step 5: Wait

Once the jaws of the ammeter are clamped into position, and they are seated properly, the ammeter will begin to register the current. This may take a few seconds so you will need to wait for the device. If it is an analog ammeter, you will notice the needle rise. If you are using a digital ammeter, the numbers will show up in the LED display. 

Step 6: Check Rating

Once the ammeter has finished taking the reading, make sure that the number displayed is the same that is on the rating tag of the item you are testing. If this is not within that range, you will know that there is a problem with the device. 

Step 7: Test Other Wires

If the AC item you are testing has multiple power wires coming into it (220 Volt, three power wire circuit, etc.), you will need to test each wire to find which one is not drawing the current that it should be.