When installing electrical controls for HVAC, how should a digital multimeter set to voltage be connected?

Connecting a digital multimeter set to measure voltage should be done in parallel with the circuit or component being tested. This method allows the multimeter to measure the voltage across two points without interrupting the current flow through the circuit. When the multimeter is connected in parallel, it takes advantage of its high internal impedance, ensuring that it does not significantly affect the circuit's operation or alter the voltage being measured.

Using a series connection would lead to an inaccurate voltage reading because the meter would become part of the circuit, affecting the current and resulting in a drop in voltage across the component being tested. Similarly, a sequence or loop connection could also interfere with the circuit logic and does not apply to standard voltage measurement.

In summary, connecting the multimeter in parallel is the proper method for accurately measuring voltage in an HVAC system, ensuring the integrity and performance of the electrical circuit remain intact.