Clear-Com MS-704 - Manual (Page 23)

M S - 7 0 4 / R M - 7 0 4 F O U R - C H A N N E L M A I N / R E M O T E S T A T I O N S
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GROUND ISOLATION
The pin #1 ground connection of each XLR connector must also be isolated
from the chassis. Pin #1 should not be connected to the shell of the XLR
connector.
Figure 2-8: Interconnect Cable Detail
Note: The remote stations connected to each channel are powered from the
intercom cable for that channel. In the case above, a short on any one
line will only take that channel down.