1.8 INTERCOM MODE WIRING – MULTIPLE UNITS
Use this wire diagram when multiple 1812 units will be connected together in an intercom mode and
connected directly to another telephone or to an open C.O. port on a PBX or KSU system. Pay
particular attention to the notes below.
Phone In - 1
Phone In - 2
Case Ground - 3
Phone Out - 4
Phone Out - 5
1812
Main
Terminal
1 - Phone In
2 - Phone In
3 - Case Ground
4 - Phone Out
5 - Phone Out
1812
Main
Terminal
Programmed for
TELEPHONE MODE
Programmed for
INTERCOM MODE
1. Up to five (5) 1812 units can be wired in series using this method. Additional units are
connected PHONE OUT to PHONE IN; PHONE OUT to PHONE IN, etc.
2. Each 1812 must be programmed for MULTIPLE SYSTEMS and each must have a
unique ATTENTION NUMBER. Each unit should also be programmed with its own
MASTER CODE.
3. The 1812 that is furthest away from the phone (phone system) must be programmed in
the intercom mode. All other 1812 units in the loop must be programmed in the telephone
mode.
4. Use only twisted pair telephone wire that has proper insulation for direct underground
burial. Do not use thinly insulated wire, even if the phone lines will be run in a conduit. Do
not make any splices to the phone lines. If splices are made, they must be soldered and
insulated in a watertight enclosure.
5. Each 1812 must be powered by its own power transformer.
6. Surge protection (DoorKing p/n 1877-010 or equivalent) is recommended for both the
phone in and phone out wires on all units in the system.
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