In control and instrumentation systems the terms dry and wetted contacts describe where the power (voltage) source is electrically located.
In a dry contact the source is in a different area than the contact. In fact the load voltage may even be from a different electrical system than the contact control voltage, such as in relay circuits. Stand alone (isolated) contacts are always "dry".
In a wetted circuit the source is located in the same electrical area as the contact. This is similar to a time clock where the contacts share the same hot conductor as the motor. Solid state (transistor) devices are additional examples. Grouped contacts that share a common hot connection point are always "wetted".
