E. Electrical Connections (see Fig. 1, 4, 5)
SHOCK HAZARD
To avoid electrical shock, do not connect wires when power is applied.
The enclosure has a motherboard that provides designated screw terminal blocks for easy and
trouble free connections of system cable. It allows sufficient space for the system cable to be
looped in and out. The wires should be properly dressed and terminated inside the enclosure. The
SelectFone stations are electrically paralleled. This allows system expansion by simply extending
the system cable from the nearest SelectFone station.
Wire the station carefully by following the wire colors and using the spade lugs as shown in Figure
4. Perform all electrical wiring per the National Electrical Code.
a. 120 VAC Power Connection
All AC power wiring to the SelectFone station is made at the three-position terminal block
JP1 mounted on the motherboard. Connect the black (HOT) 14 AWG conductor of the in-
coming and outgoing cable to H terminal. Connect white (NEUTRAL) 14 AWG conductor
to the terminal marked N. Connect the green/yellow (earth ground) 14 AWG conductor to
the terminal marked GND.
A green 14 AWG ground conductor should be part of the system cable where no conduit or
non-metallic conduit is used. If a non-metallic enclosure is used with metallic conduit and
cable without ground conductor, there absolutely must be an electrical bond between conduit
and terminal marked GND at terminal block JP1 of the SelectFone station.
EQUIPMENT DAMAGE HAZARD
No SelectFone station should be installed or operated without having proper
ground continuity.
b. 24VDC Power Connection for 24VDC SelectFone
The 24VDC SelectFone system stations are designed for operation from a 24VDC,
rechargeable battery. A charger can be connected to maintain the batteries. Ground the
negative side of battery only at one point for the system to reduce the hum and noise in the
24VDC SelectFone system.
EQUIPMENT DAMAGE HAZARD
Do not operate 24VDC SelectFone system stations from a charger without a 24V battery
connected to it because high, no load voltage (30V to 40V) of a 24V charger can damage
the equipment. Never connect 24VDC SelectFone station to a supply
voltage greater than 28VDC.
All SelectFone system stations are connected in parallel. 24VDC stations draw 1.5Amp. Max.
current when page amplifier is driven by sine wave signal producing 12 watts in to an 8-ohm
speaker. When planning 24VDC SelectFone system layout, careful consideration should
be given to the power cable losses due to the voltage drop caused by cable resistance. To
reduce the voltage drop in the long cable length it is recommended that several branches from
24VDC-power source be used to power the system and no more then six (6) stations should
be connected to each power cable branch. An adequately rated fuse or a circuit breaker at
the 24VDC source should be used to protect each power cable branch. For a 14 AWG power
line this fuse or circuit breaker should be rated at 15 A. The rating of the protection device is
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