Figure 11: Class "B" Single Direction Loop (Star Configuration); Figure 12: Class B Single Direction Loop With Tee Offs - Interlogix FP 2000 Series Installation And Commissioning Manual

Figure 11:
Figure 12:
A maximum of 126 detectors (900 Series) or 128 detectors (2000 Series) can be
connected to a loop. For combinations of fire sensing devices, monitoring controllers and
input/output devices, the maximum number of addressable units must be calculated.
Please refer to the Installation Manual of the 900 Series and 2000 Series detectors.
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Class "B" Single direction loop (Star configuration)
Class B single direction loop with tee offs
EN54 specifies that a short circuit or an interruption in a detection circuit
cannot prevent the indication of a fire alarm from more than 32 fire detectors
and/or manual call points.
Therefore, when more than 32 detectors are connected to one loop, an
isolator should be placed at least at every 32 devices. In that case, a class A
configuration (no Tee Offs) should always be used.
EN54 specifies that in case of a system fault, not more than 512 fire
detectors and/or manual call points and their associated mandatory functions
shall be affected. Taking this into consideration, the amount of detectors per
panel should be limited to 512.
FP/FR1100/1200/2000 V6: Installation and Commissioning Manual