A relay contact is a “dry” contact; This means that no voltage is coming out!
The contact is completely separated from the circuit and can be used in your application without risk.
Usually contact has two positions, using one common contact:
NO: Normal open (Closed when the relay is activated)
NC: Normal closed (Open when the relay is activetad)
Hereby a link to a diagram that shows how to connect a relay contact to turn on/off your circuit:
http://www.velleman.be/images/tmp/relais.JPG
