Using multimeter to measure resistance

Discussion in 'General Electronics Chat' started by ghall426, Jul 22, 2009.

  1. ghall426

    Thread Starter Member

    Jul 22, 2009
    11
    0
    I understand that there should be no voltage across a component while measuring its resistance with a multimeter. In fact, my user manual specifically states "NEVER connect the meter leads across a voltage source while the function switch is in the resistance or diode mode."

    Why, then, does both the user manual and back of the packaging of the multimeter box show the following on an "input limits" chart?

    Function: Resistance
    Maximum input: 250V DC/AC
     
  2. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    Because the manual and box was printed in a country where English is not the primary language.
     
  3. someonesdad

    Senior Member

    Jul 7, 2009
    1,585
    141
    Because meter manufacturers know that people will make mistakes and connect a meter in resistance mode across an AC line, the meter needs to be protected against such mistakes. Why? Because other manufacturers do so and if one didn't, the user would toss the broken one away and buy one from the competition. Besides, idiots like me would measure the resistance of the AC line, blow the meter, and then declare the meter to be no good.

    This spec is typically what the instrument is designed to take without damage.

    Note there are multimeters designed to take resistance measurements in the presence of small DC voltages; the feature is usually called "offset compensation". An example is measuring the resistance of a relay contact where thermoelectric voltages are present.
     
  4. mdv1982

    New Member

    Jun 22, 2009
    7
    0
    the 250V DC/AC maybe not considered with the measuring specifications for resistance,it is for the safe voltage for the multimeter.
     
Loading...