Current measurement requires an entirely different technique than was
used in voltage measurement. To perform a current measurement
ammeter must be placed in series with the component in which the
current is being measured. This involves breaking the circuit
placing the meter across the break, completing the circuit again.
1. Always check the fuses and the current
ranges on the meter, using the test fixture, before beginning!
2. Connect the leads to the appropriate
Simpson 270: Red lead
>> +, Black lead >> COM (Except
Fluke DMM: Red lead
>> 300mA , Black lead >> COM
(Except 10A measurement)
3. Set the meter to the appropriate range.
If uncertain, set the
meter to the highest current range and work down when measurement is
Typical setups are shown below.
4. Find the resistor through which the
current is to be measured.
5. Create a break in the circuit by
moving one lead of the resistor.
6. Use the meter to jumper across the
break. This puts the meter in series with the component.
7. Read the current flowing through the
Simpson 270 – Find the appropriate scale and
determine the reading
Fluke DMM – Read the LCD panel to determine the
current in mA.
8. Process repeated for a second
the meter across the break