For general purpose switching applications like process control, warning devices, simple building automation and even control of door locks, etc., the 8 Relay Expander Board adds 8 relays which can switch high-current, low-voltage loads. One versatile 8-Way relay board can be fitted to a Concept 3000/4000 Control Module and Mini Expander whereas up to 4 may be attached to a single Universal Expander by means of a Relay Extension Cable (IR-995019).