DPDT relay contacts provide two independently switched circuits, with each circuit offering a common, normally open, and normally closed connection for routing or changing signal paths. Dry-contact outputs describe how the output behaves electrically, supplying no voltage of their own, so they can switch an external circuit when paired with the appropriate power source and load.

Compare the relay’s contact rating at the actual load voltage and current, noting that AC and DC ratings can differ, and that a relay rated for 5 A at 28 VDC may not support the same current at a higher voltage or with an inductive load. For access control devices, AV equipment, and other low-voltage loads, account for startup or inrush current, check whether the application needs normally open, normally closed, or dry-contact operation, and select a DC relay module with ratings above the expected steady-state and switching load.

DC relay modules are available as Snap Track-mountable boards, standalone relay boards, and access power controllers supplied in an enclosure. Some four-relay control modules support surface mounting or free-standing placement, while removable terminal blocks on select controllers can help simplify wiring during installation.

DC relay modules use a DC-controlled coil and changeover contacts to switch a circuit between normally open and normally closed states, with some models providing configurable contact operation. For latching applications, select a module designed for latching dry-contact control, while access power controllers can provide independently controlled outputs with fail-safe or fail-secure operation.