Notifier LCD-80, Installation Manual

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PN 15037:D2 9/9/02 45
APPENDIX A EIA-485 Shield
Terminations
The EIA-485 circuit must be wired using a twisted-shielded pair cable
having a Characteristic Impedance of 120 ohms, +/- 20%. Do not run
cable adjacent to, or in the same conduit as, 120-volt AC service,
noisy electrical circuits that are powering mechanical bells or horns,
audio circuits above 25 Vrms, motor control circuits, or SCR power
circuits.
All enclosures, including the FACP backbox, must be
connected to earth ground! Never use the shield for grounding
purposes.
When employing the LCD-80 in ACS Mode:
Terminate the EIA-485 shield at the Fire Alarm Control Panel only.
When the EIA-485 shield is in conduit: Connect it to system reference
(system common). The shield can enter the cabinet, but must be
insulated from the cabinet (not electrical contact). Between LCD-80s,
wire-nut multiple shields together (which can be inside of the
respective enclosure).
When the EIA-485 shield is not in conduit: Terminate the shield at the
outside of the FACP backbox (ground). Do not allow the shield to
enter or even touch the cabinet. Between LCD-80s, wire-nut multiple
shields together outside of the respective enclosures.
Note on remote power supplies:
When the LCD-80 is powered from a separate power supply, use a
separate conductor to connect the main power supply common
terminal to the remote power supply common terminal. Disable earth
fault detection on the remote power supply. AM2020/AFP1010 and
System 5000s with an AIM-200 installed would require an MPS-24A
(or an MPS-24B with an EFB-1 installed) in its main cabinet.
When employing the LCD-80 in Terminal Mode:
Terminate the EIA-485 shields at either the cabinet (when not in
conduit) or at system common (when in conduit) as outlined below.
AM2020/AFP-1010 Note: Terminate EIA-485 shields at both the Out
and Return ends of the CCM-1, DIA-1010 or DIA-2020.
When the EIA-485 shield is not in conduit: At each respective LCD-
80 enclosure (except the first on the loop), terminate the shield
coming in from the previous LCD-80 at the outside of the cabinet
backbox (earth ground). Let the outgoing (to next LCD-80) shield
float (no connection). Shield termination between LCD-80s can only
occur at the receiving end - the end connected to P1 Terminals 2