How would you verify proper polarity of a two-wire control cable?

How would you verify proper polarity of a two-wire control cable?

• A. Check color coding of insulation only.
• B. Visual inspection of connectors only.
• C. Assume correct if device responds.
• D. Check continuity and polarity against the schematic and device terminals.

Answer: (D)

Verifying proper polarity means confirming that each conductor in the two-wire control cable goes to the correct terminal as shown on the schematic and on the device. To do this, trace the wires with a continuity tester or multimeter from the control cable back to the device terminals and map them to the schematic designations. The wire connected to the device’s designated positive terminal must be the same conductor tied to the positive supply, and the other conductor must go to the negative or return terminal. Relying on color alone is risky because insulation colors can be mislabeled or changed, and simply inspecting connectors won’t reveal a swapped pair. A device might respond even if polarity is wrong, but that isn’t a guarantee of correct or safe wiring. Checking continuity and ensuring the conductors match the schematic and device terminals provides accurate polarity verification.

Verifying proper polarity means confirming that each conductor in the two-wire control cable goes to the correct terminal as shown on the schematic and on the device. To do this, trace the wires with a continuity tester or multimeter from the control cable back to the device terminals and map them to the schematic designations. The wire connected to the device’s designated positive terminal must be the same conductor tied to the positive supply, and the other conductor must go to the negative or return terminal. Relying on color alone is risky because insulation colors can be mislabeled or changed, and simply inspecting connectors won’t reveal a swapped pair. A device might respond even if polarity is wrong, but that isn’t a guarantee of correct or safe wiring. Checking continuity and ensuring the conductors match the schematic and device terminals provides accurate polarity verification.