20
The table below shows the maximum SLC wire branch length based on supervision communications.
Table 8. Maximum SLC Wire Branch Length Based on Supervision Communications
Distance in Feet (Meters) to the Last Appliance
Unit Load Range
18 AWG (0.82 mm
2
)
14 AWG (2.08 mm
2
)
12 AWG (3.31 mm
2
)
1
658 ft (201 m)
1,681 ft (512 m)
2,500 ft (762 m)
2 to 3
602 ft (183 m)
1,536 ft (468 m)
2,500 ft (762 m)
4 to 7
514 ft (157 m)
1,310 ft (399 m)
2,086 ft (636 m)
8 to 13
422 ft (129 m)
1,073 ft (327 m)
1,709 ft (521 m)
14 to 20
350 ft (107 m)
887 ft (270 m)
1,411 ft (430 m)
21 to 30
282 ft (86 m)
712 ft (217 m)
1,131 ft (345 m)
31 to 40
237 ft (72 m)
595 ft (181 m)
944 ft (288 m)
41 to 50
204 ft (62 m)
511 ft (156 m)
811 ft (247 m)
51 to 60
180 ft (55 m)
449 ft (137 m)
711 ft (217 m)
61 to 75
153 ft (47 m)
379 ft (116 m)
600 ft (183 m)
For Class B wiring with no isolators, T-Tapping is allowed. SLC wiring may be split multiple times to
form SLC wiring branches. Maximum wire distance of each of these SLC branches from the panel to
any device is the smaller of the values obtained from Table 7 and Table 8. Add the alarm loads of all
of the devices on an SLC branch and apply to Table 7. Add the unit loads (see Table 4) of all the
devices on an SLC branch and apply it to Table 8. Use of Table 7 and Table 8 requires all SLC wire
branches join within 10 feet (3 m) of the panel. T-tap wire stubs are allowed on the SLC wire
branches, but each tap must be less than 100 feet (30 m).
FigureTag FD9-336-05
TRUEALERT
APPLIANCE
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Ferrite
Bead
Figure 8. Class B Wiring, No Isolators
Continued on next page
Wiring Class B Circuits,
Continued
Class B Guidelines
Class B
Wiring Diagram
(No Isolators)
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