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Document 15342 Rev D1 07/24/97 P/N 15342:D1
Fire Alarm Control Panel
Section Two
Design Considerations
ACM-8R
Limits
The ACM-8R is a member of the Notifier ACS class of annunciators. Up to 32
annunciators may be installed on an EIA-485 circuit. The actual number of annunciator
modules may be larger depending on the number of expander modules employed.
Wire Runs
Communication between the Control Panel and the ACM-8R is accomplished over a
power-limited two-wire EIA-485 serial interface. This communication, to include the
wiring, is supervised by the fire alarm control panel. Power for the annunciators must be
power-limited and is provided via a separate power loop from the control panel which is
inherently supervised (loss of power also results in a communication failure at the control
panel).
*Note for AM2020 installations only: SIB-2048 can support two EIA-485 circuits,
each capable of spanning 6,000 feet @ 16 AWG. For more details, refer to
Appendix B: ACS and the AM2020.
Wiring Specifications
The EIA-485 circuit cannot be T-Tapped; it must be wired in a continuous fashion from
the control panel to the annunciator. The maximum wiring distance between the
panel and the last annunciator is 6,000 feet @ 16 AWG.
The wiring size must be a 12 AWG to 18 AWG twisted
shielded pair cable having a Characteristic Impedance of
120 ohms, +/- 20%. Limit the total wire resistance to 100 ohms on the EIA-
485 circuit, and 10 ohms on the annunciator power circuit. Do not run cable adjacent to,
or in the same conduit as, 120 VAC service, noisy electrical circuits that are powering
mechanical bells or horns, audio circuits above 25 volts
RMS
, motor control circuits, or SCR
power circuits.
Two-wire EIA-485 Circuit*
(Maximum of 6,000 feet)
power-limited
ACM-8R Power
(12 to 18 AWG )
power-limited
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