Introduction: CLAMP THOSE AMPS

Picture of CLAMP THOSE AMPS

Make an corded adapter for a clamp amp meter to measure the current draw of household devices. Can be used as a troubleshooting tool and to measure the load of multiple devices connected to an outlet. You can insert the cord before power strips, your computer, monitor etc to get the total current draw of those devices. It can also be used for checking power draw on motors , air conditioner, etc. You can use this setup to read any 120VAC device. A simple calculation of the amperage reading multiplied by the voltage will give you an approximate wattage figure.
This meter also has a HOLD button that will capture the highest reading such as inrush current.
Also one of these could be constructed for 220 VAC devices using the proper connectors to measure the current on both sides of the circuit.

Step 1: Needed Items

A clamp type ammeter, this one was on sale for $7.99 (Harbor Freight).
A short extension cord OR:
1male 3 prong cord end,
1female 3 prong cord end,
1 length of 3 conductor cord.

Step 2: Separate One Conductor of the Cord

Picture of Separate One Conductor of the Cord

using a knife etc. carefully cut apart and separate ONE of the conductors of the cord for a short length.
According to the instructions with the meter it should be the hot side. Tape up and tie off the split make sure there is no bare wire showing . It should be long enough for your clamp amp clamp to fit through.

Step 3: Connect the Cord Ends

Picture of Connect the Cord Ends

If you are using an extension cord this step isn't necessary.
Attach the cord plug and receptacle ends to the cord.
I used heavy duty ones as shown here .
Follow the wiring straight through , white to white, black to black, ground to ground.The separated single wire from the previous step should be on the hot side or black.
These connectors were marked white, black and ground. Double check your connections.

Step 4: Clamp the Meter Through the Single Wire

Picture of Clamp the Meter Through the Single Wire

Step 5:

Picture of

Connect your device inline through the cord. In this example a toaster oven.

Step 6: Read the Amperage.

Picture of Read the Amperage.

Set the meter to amps, activate the device and read the current.
You can insert the cord before power strips, your computer, monitor etc to get the total current draw of those devices. It can also be used for checking power draw on motors , air conditioner, etc. You can use this setup to read any 120VAC device. A simple calculation of the amperage reading multiplied by the voltage will give you an approximate wattage figure.
This meter also has a HOLD button that will capture the highest reading such as inrush current.
Also one of these could be constructed for 220 VAC devices using the proper connectors to measure the current on both sides of the circuit.

Comments

Phil B (author)2008-12-15

I purchased a clamp amperage meter similar to the one you show, except that it was analog with a needle rather than digital. It also cost a bunch more, but I really needed it at the time. It did come with an accessory that eliminates the need to separate a conductor on the power cord. It has a female receptacle for the power cord. It also has a male end for the wall socket. And, there is an open square loop through which I can clamp the ammeter jaws. The current reading appears on the dial. You could also make up an accessory that consists of a male plug, a female plug, and individual strands of insulated wire. Just plug it into the wall and plug the appliance into it. Clamp the ammeter jaws around one of the wires. There would be no need to cut into the cord. Further, some cords do not lend themselves to cutting because their conductors are gently twisted around one another and the plastic tube surrounds them.

pmetro (author)Phil B2008-12-15

Yep, your right, you could use a lenght of stripped romex to get 3 separate wires. The cord I used is more flexible than romex and easier to store than solid wires. It was a spare cord not being used. Thanks for your comments Phil

Phil B (author)Phil B2008-12-15

Oops! The cord you cut into is an accessory cord, not the actual appliance cord. I did not catch that. Sorry.

rimar2000 (author)2008-12-15

Very useful device, very useful instructable. Thanks.

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