When measuring resistors designed for temperature measurements or other resistive devices that vary with temperature, be aware that the meter will dissipate some power in the device-under-test. The effects of this power dissipation can affect the measurement accuracy.

If power dissipation is a problem, you can select a higher measurement range, one which uses a lower current source thus reducing the self-heating. Some multimeters, such as the 34420A offer a low power setting. Using the low power setting or a higher resistance range requires a multimeter with good resolution. Below is a table showing the power dissipated by a resister by range and how a low-power setting can reduce the power.

  Normal Normal Low Power Low Power
Range Test Current DUT Power at Full Scale Test Current DUT Power at Full Scale
1Ω 10 mA 100 µW 10 mA 100 µW
10Ω 10 mA 1 mW 10 mA 1 mW
100Ω 10 mA 10 mW 1 mA 100 µW
1kΩ 1 mA 1 mW 100 µA 10 µW
10kΩ 100 µA 100 µW 10 µA 1 µW
100kΩ 10 µA 10 µW 5 µA 2.5 µW
1MΩ 5 µA 25 µW 5 µA 25 µW

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