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.
3.2
Wire Size
The D278S and D298S can accept any wire from 12 AWG (2.0 mm) to 24 AWG (0.3 mm). The minimum wire
size required by the D278S and D298S is determined by the maximum number of bases used and the maximum
distance from the FACP to the most remote base. Refer to Table 1 for the number of D278S and D298S in a
circuit and their corresponding wire gauges.
Table 1:
Bases and Wire Gauges
Number of D278S
and D298S Bases in
22 AWG (0.8 mm)
Circuit
1 to 70
1822 ft (555 m)
71 to 80
1594 ft (486 m)
81 to 90
1417 ft (432 m)
91 to 100
1275 ft (389 m)
101 to 110
1159 ft (353 m)
111 to 120
1063 ft (324 m)
Use 16 AWG (1.5 mm) gauge wire ratings for 12 AWG (2.3 mm) and 14 AWG (1.8 mm).
3.3
Multiple D278S or D298S Bases
Figure 2:
Multiple D278S and D298S Bases
1
+
2
-
-
3
+
1 - D278S or D298S Addressable Smoke Detector Base
2 - Switched auxiliary power
3 - POPIT bus
Bosch Security Systems, Inc. | 11/10 | F01U069160-11
20 AWG (1.0 mm)
2898 ft (883 m)
2536 ft (773 m)
2254 ft (687 m)
2028 ft (618 m)
1844 ft (562 m)
1690 ft (515 m)
2
3
1
4
+
-
Z
Z
D278S/D298S | Installation Guide | 3.0
Wire Gauges
18 AWG (1.2 mm)
4608 ft (1405 m)
4032 ft (1229 m)
3584 ft (1092 m)
3225 ft (983 m)
2932 ft (894 m)
2688 ft (819 m)
2
3
1
4
-
+
Z
Z
Wiring
16 AWG (1.5 mm)
7327 ft (2233 m)
6411 ft (1954 m)
5699 ft (1737 m)
5129 ft (1563 m)
4663 ft (1421 m)
4274 ft (1303 m)
1
3
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