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GAI-Tronics Clean Phone 295F マニュアル
Model 295F and 295W Clean Phone™ Telephone
Power and Wiring Information (Level C Power)
The Model 295F and 295W Clean Phones are powered from a 48 V dc @ 250 mA power supply. The
power supply should be Nationally-Recognized Testing Laboratory (NRTL) listed per UL specification
UL 1012 or equivalent.
If these clean telephones are powered through the black and yellow "spare pair" in the telephone cable,
the power to these wires must be limited to UL Level C power. To meet the requirements for Level C
power, the current to the telephone must be limited to 1 ampere maximum at 48 V dc.
The GAI-Tronics Model 237 Power Supply is a 48 V dc @ 250 mA UL listed power supply that can be
used to power a single Model 295 Clean Phone. See Figure 4 for wiring details for the Model 237 Power
Supply.
The distance between a telephone and the 48 V dc power source is limited only by the maximum
allowable wire resistance, (32 ohms). See the table for calculated distances for standard wire sizes.
AWG
24
22
20
19
18
16
14
Refer to the table provided above. When using 24 AWG wire, the 48 V dc power source can be located
up to 620 feet, 190 meters, or 0.11 miles away from the phone. Paralleling pairs of the same gauge wire
will increase operating distance by a factor of two.
d:\standard ioms - current release\42004 instr. manuals\42004-146h.doc
11/05
Calculated Distance for Standard Wire Sizes
Feet
620
985
1585
1985
2500
3980
6350
Figure 4. Model 237 Power Supply Wiring
Meters
Miles
190
0.11
300
0.18
480
0.30
605
0.37
760
0.47
1210
0.75
1935
1.2
Pub. 42004-146H
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