What resistance should be expected between the red and white wire of a 4 wire 100 ohm PT RTD checked at 32°F?

The expected resistance between the red and white wire of a 4 wire 100 ohm Platinum Resistance Temperature Detector (RTD) at 32°F (0°C) is indeed 100 ohms. This is because a 100 ohm RTD is designed to have a resistance of 100 ohms at 0°C, which is the standard reference point for measuring the resistance of PT RTDs.

RTDs operate on the principle that the resistance of a metal increases with temperature. For a 100 ohm RTD, the specified resistance at 32°F (0°C) is exactly 100 ohms. This resistance value is crucial for accurate temperature measurement because the readings derived from the RTD depend on knowing the resistance accurately at specific temperatures.

The other resistance values listed (0 ohms, 108 ohms, and 120 ohms) do not align with the standard characteristics of a 100 ohm PT RTD at the specified temperature. A reading of 0 ohms would indicate a short circuit, while values of 108 ohms and 120 ohms suggest an increase in resistance that typically corresponds to higher temperatures above the calibration point for a 100 ohm RTD.