What would cause a voltage reading across a closed contact in a 24V control circuit?

The correct answer highlights that pitted or dirty contacts can lead to an unintended voltage reading across closed contacts in a 24V control circuit. When contacts are dirty or damaged, the electrical connection may be compromised, resulting in a resistance in the circuit. This condition can create a situation where voltage appears to rise across the contacts even when they are closed. Ideally, closed contacts should offer very little resistance, allowing current to flow freely and maintaining a consistent voltage reading. However, the presence of contaminants or physical wear can interfere with this ideal scenario, leading to misleading voltage readings.

In the context of the other options, while a true RMS meter is designed to measure voltage accurately under varying waveforms, it does not correlate to why voltage would appear across closed contacts specifically. The suggestion that 24V is "sneaking" from another part of the circuit typically implies a leakage issue, which does not directly connect to the presence of legitimate voltage across a closed contact due to dirt or wear. Lastly, asserting that voltage across closed contacts is normal operation overlooks the impact that contact quality has on readings, as healthy, clean contacts should not show significant voltage when measured directly. Therefore, the state of the contacts—being pitted or dirty—directly contributes to