Wiring a Fan to Expansion Board using the Relay
When connecting to the controlled Outputs (that are using mosfet's) make sure that these loads do not have large inrush currents. The typically DC-DC or other components have capacitors can draw large inrush currents when first switched on compared to their continuous running consumption. Watchmon supervisor and expansion boards outputs are rated to 3A (default), they will fail when the inrush currents exceed their rating (x2 even for micro/milliseconds).
For large (or unknown) loads make sure you use a external relay/SSR (solid state relays) that is appropriate for the rated purpose.
Connecting a 12v or 24v Fan to the Relays on Expansion Board
Locating Relay connector on the Expansion Board