TATTLETALE® annunciators and Magnetic Switches are the nerve centres that translate Switchgauge contact operations into decisions and operate the alarm or shut down device. They are electrical load carrying devices for the alarm or shut down device. TATTLETALE® annunciators indicate which monitored function failed leading to the alarm or shutdown whereas magnetic switches do not. Magnetic switches operate basically as a latching relay. 518APH allows for Switchgauge and/or N.C. contacts to be wired “Closed Loop” (in series). Any contact open or Switchgauge contact close in the circuit shunt trips the 518APH. Specify 12 or 24 VDC. Contacts 10 amps 24V. 14 amp fuse.