By Purkeys | Sep 21, 2016

Purkeys Electrical Tool Kit comes with a variety of useful tools to help technicians test and diagnose heavy-duty vehicle electrical systems. This week, we will be spotlighting one of the tools in this kit—the clip-on ammeter.

Unlike the ammeter function of a standard multimeter, which we discussed previously here, the clip-on ammeter measures current through the magnetic field generated by the current flowing through the conductor. By simply clipping the interlocking jaws of the ammeter around the wire, you can get an accurate measurement without breaking the circuit to take the reading.

In this video, Larry Rambeaux demonstrates how easy it is to use the clip-on ammeter. Larry notes two important things before he begins: 1) the ammeter has both 40 amp and 400 amp settings, and 2) the arrow inside the jaws indicates which direction the current should be flowing. If you clip the ammeter on with the arrow facing the wrong way it will still work, but will show a negative value.

In past videos, we have talked about the importance of checking for parasitic loads. The ammeter is perfect for that; it can check a cable for a high load without disconnecting anything. It can also be used to check alternator or liftgate cables; simply clip it on and see how much current is flowing.

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