Home >> Science & Nature >> Science

How to Use a Clamp Amp Meter

Using a traditional ammeter to measure the current flowing through a wire is potentially dangerous. Unlike voltage, which can be measured across a circuit, a normal ammeter must be placed in series with the circuit, necessitating the disconnection of a wire. The circuit must then be switched on and the reading taken. Clamp ammeters dispense with this potentially dangerous step and measure the current in a non-invasive way by determining the strength of the magnetic field surrounding the wire.

Instructions

- 1
  Switch on the clamp ammeter. If the meter is fitted with a battery test facility, use it. Heavily discharged batteries may result in inaccurate readings. Read the manufacturer's instructions, from start to finish, if you are unfamiliar with the meter's functions.
- 2
  Adjust the rotary switch to select an appropriate range. If you are uncertain of the current, select the highest range available. If the meter is auto ranging, the meter will calibrate itself automatically.
- 3
  Open the clamp-meter jaws by squeezing the trigger. Identify the wire in which you wish to measure the current, usually the black wire -- the one carrying the power -- then guide the jaws around it. If the wire is within a cord containing several wires, separate them by using a break-out cord, a special length of cord from which the outer insulation has been removed.
- 4
  Close the jaws by releasing the trigger. Observe the meter display. This shows the current flowing through the wire.

Science