Which of the following is NOT listed as a common input voltage level for PLC input modules?

• A. AC 120
• B. DC 60
• C. DC 5
• D. AC 220

Answer: (B)

Understanding what input voltages PLC input modules are designed to read helps you pick compatible hardware and wiring. PLC input modules come in two main families: AC inputs and DC inputs. AC input modules are typically rated for standard line voltages you’d find in buildings, such as 120 VAC or 220–240 VAC. DC input modules use low- to mid-range DC voltages common for sensors and control circuits, like 5 VDC for simple logic or 12–24 VDC for general industrial use (and sometimes higher, such as 48 VDC, depending on the system).

A voltage like 60 VDC isn’t a standard listing you’d commonly see for PLC input modules. It isn’t a typical or widely supported option across many PLC families, so it wouldn’t be expected as a common input level. In contrast, 120 VAC, 220 VAC, and 5 VDC are among the standard, commonly listed levels you’d encounter.

So the statement that DC 60 is not listed as a common input voltage level is the best fit.