Sentry Model HM-535 Power Supply
Installation and Service Manual
430-535 0104 © 2004 Heritage MedCall, Inc.
10
7.1
VOLTAGE REQUIREMENTS
All Sentry apartment devices have been specifically designed to minimize current
requirements. Devices such as host panels and smoke detectors will operate below 9
volts, however Sentry specifies that the panels and smoke detectors MUST have at
least 9.0 Volts to perform properly.
7.2
VOLTAGE DROP
Voltage drops are voltage losses in the wiring. As current increases, the loss increases,
and the voltage available to the devices is decreased. To reduce voltage drops, the
number of apartments connected to a single cable and cable length is limited. See the
Sentry Wiring Design Guide (390-108) for more information.
Increasing wire gauge will decrease voltage drops. At buildings with a long distance
between the power supply, terminal block, and the closest room panel, it is
recommended to install a 14 gauge wire pair for the DC power, to the first panel on the
cable length. The number of apartments that can be connected to a common power and
data cable is significantly lower when the system is connected to a fire alarm interface.
The fire alarm interface can activate all the smoke detector horns simultaneously. The
higher current from all the smoke detectors sounding at one time creates higher voltage
drops.
