All Locally Powered Intercom Stations (Dry Lines)
If intercom stations are widely distributed, you can dispense with a system power supply (PS2001L, SPS-2001, etc.) and use local power for each station. When no power is delivered on the intercom channels, this is known as dry-line operation. Since a system power supply is not used, a line termination must be inserted in each intercom channel for proper operation. Again, not that only the U box has provisions for local power, the 3-pin connectors on the S, P, and RM version do not permit this type of connection. Figure illustrates an intercom system using all locally powered U boxes.
FIGURE 6. Intercom system using all locally powered U box stations.
An example (as shown in Figure 6) of an Audiocom intercom system using all locally powered U box stations, with no power being distributed on the intercom channels (dry lines). Since an Audiocom power supply is not used, the installer must connect a line termination somewhere in each channel for proper operation.
FIGURE 7. Audiocom mode line termination for dry-line operation. (One required for each channel). The termination is available via P/N 9020-7550-000.
