AT&T Bell System Plant Series Installation And Maintenance Manual

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BELL SYSTEM PRACTICES
Plant Series
SECTION 512-515-200
Issue 5, December 1967
AT&TCo Standard
INTERPHONE SYSTEM- 2A FARM
INSTALLATION AND MAINTENANCE
CO AND INTERPHONE LINES
54-TYPE CONTROL UNIT
(LOCATE NEAR MONITOR STATION)
INDOOR REMOTE STATIONS
CO AND INTERPHONE LINES
CENTRAL OFFICE
~- ... LINE
INTERPHONE LINE ONLY
MONITOR STATION
OUTDOOR
REMOTE LOUDSPEAKER
fig. 1 -Typical 2A Farm lnterphone Arrangement
1. GENERAL
1.01
This section is reissued to:
• Include schematic diagrams of control
unit formerly found in Section 512-515-400.
• Include information on 54B control unit
and E1D ringer.
• Show that the 54A control unit and E1B
ringer are rated MD.
Since this reissue covers a general rev1s10n, ar-
rows ordinarily used to indicate changes have
been omitted.
2. INSTALLATION
(a) Planning
(1) When planning the 2A farm interphone
installation, consider the following:
• Avoid placing apparatus with plastic
covers or parts in locations where the
ambient temperature may exceed 140
degrees F.
• Any combination up to a total of six
loudspeakers may be used, provided, no
more than three are outdoor speakers
©American Telephone and Telegraph Company, 1967
Printed in U.S.A.
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