Volt free contacts or volt free switching does not operate a
system without any voltage as the description of it may imply.
Volt free contacts or volt free switches are invariably
mechanical contacts with no electrical connection to any other part
of the equipment the contacts being open and closed mechanically by
a solenoid or other device. A relay is an example of a volt free
contact device as the operating coil is not connected to the
contact(s) and will usually have a Common and a Normally open and a
Normally closed set of contacts.
Volt free contacts or switching allow the user to switch a range
of voltages from 24 up to 230 volts, by applying their particular
voltage to the Common terminal and connecting their appliance to
either the Normally open or Normally closed contacts, depending on