36
en | Installation wiring
PRAESENSA
2021.12.21 | V0.15b | F.01U.402.882
Underwriters Laboratories Listing Document (ULLD)
Bosch Security Systems B.V.
Parts check and identification
x8
x2
x1
x2
x1
B
x4
D
C
H
x12
E
F
G
A
Amplifier
B
2-pole screw plug (x2)
C
6-pole screw plug (small)
D
6-pole screw plug (large, x4)
E
Wire‑end ferrules (small, x12)
F
2-conductor cable (x2)
G
6-conductor cable
H
Wire‑end ferrules (large, x8)
3.4.4
Safety ground
Connecting the chassis ground screw to safety ground is mandatory for the PRAESENSA
power amplifiers:
–
The safety ground connection is needed for safety because of high internal voltages. All
PRAESENSA 19”‑devices have a chassis ground screw on the rear panel, which can be
used for a wire connection to the rack frame. The rack frame must be grounded to safety
ground. This is a conductive path to ground or earth that is designed to protect persons
from electrical shock by shunting away any dangerous currents that might occur due to
malfunction or accident. Use a thick, multi strand wire (>2.5 mm
2
) with wire eyelets and
washers for a solid connection.
–
The safety ground connection is needed as reference for the ground short detection
circuit. Without this connection, the amplifier could be electrically floating and no ground
shorts or leakage currents would be detected for loudspeaker lines that touch ground
somewhere. The safety ground connection via the mains connection of the multifunction
power supply cannot be relied on for this, because the mains cable of this supply could
be unplugged and then the amplifier continues to work on the backup battery.
