"Dry contacts'' usually means that it has no voltage applied to the contacts at all from its initiating equipment. This allows a remote piece of equipment or instrumentation to use its own control loop and "loop through" the "dry contacts". So two or more pieces of control equipment are not electricaly common, but only mechanicaly common.
in addition, you can always create your own "dry contacts'' by adding a relay with the coil voltage being the same as your control voltage. Let the control voltage energize the coil, then use one of the relays contacts to supply a contact closure to a remote location or piece of equipment....
Thats a crude explanation but hope it helps....
Yes, Im stubborn as a mule..that's why,
I'm a "Has Been" that "Never Was"