Bosch MB-FJ Installation Manual

MB-FJ

Fire Phone Wall Jack

The MB-FJ is a fireman’s phone jack station to be located at strategic places in a building for two-way
communication to the master station. In operation, a fireman plugs in a MB-FH handset, which rings in at
the master station. The operator can then pick up the master handset, select the switch, and talk with the
fireman at the remote station. Construction is simply a single-gang stainless steel plate with a 1/4” phone
jack, intended to be mounted to a standard single-gang electrical box.

Fig.1
Front Plate

FIREMAN

PHONE

Fig.2
Wiring

red

P/N B-5038 REV. C
Page 1 of 2

black

130 Perinton Parkway, Fairport, NY 11450
Customer Service: [phone]
Technical Support: [phone]

Fig 3
Sample Connection Details

red

black

To insure proper supervision, break wire run
from input to output. Do not wire nut input
and output wires together

Max. wire resistance

50 Ohms

Supervised, Power Limited
Ground faults are indicated
at 10K impedance or less.

1 2 3 4

1 2 3 4

1 2 3 4

MBR

To next device:
10K EOLR at last
device only. Use
Listed EOL device.

1 2

1 2 3 4

1 2 3 4

P/N B-5038 REV. C
Page 2 of 2

Field wiring connections:

#6-32 wire clamp screw 14-18 AWG
#8-32 wire clamp screw 12-18 AWG

Horizontal wire entry terminal 18-26 AWG

Wire gauge determined by circuit load

130 Perinton Parkway, Fairport, NY 11450
Customer Service: [phone]
Technical Support: [phone]