14
Normally Closed Circuit
This is a 2-wire non-supervisory circuit and is
supported by the MR-2928 module. This circuit is
listed by UL for connection to other control
equipment through less than 20 feet of conduit.
Devices are connected as illustrated in Figure 11.
Maximum wire lengths are shown in Table 2.
Normally Open Circuit
This is a 2-wire supervisory circuit. It is supported by
the MR-2928 module. This circuit is listed by UL for
connection to other control equipment through less
than 20 feet of conduit. Devices are connected as
illustrated in Figure 12. Maximum wire lengths are
shown in Table 2.
Table 2: Maximum Wire Lengths for Conventional Input Circuits
Addressable Style 4 (Class B) Circuit
This is a 2-wire power-limited and supervised Style 4
(Class B) communications circuit using addressable
devices. It requires the use of the MR-2929 or MR-2909
module. Wire capacitance and resistance affects the
allowable wire length. The recommended wiring is
twisted unshielded pair. Consult Secutron's
Applications Department for specific requirements.
Maximum wire lengths are up to 10,000 ft (see Table
3). Devices are connected as illustrated in Figure 13.
Use only approved devices
.
Notes:
• This circuit shall not be used to monitor fire alarm or supervisory initiating devices. This circuit
may be wired on any of the 24 input circuits on the MR-2900 terminal boards.
• All distances refer to total wire length.
Note:
No fire alarm initiating devices can be connected to this class of circuit. This circuit may be wired
on any of the 24 input circuits on the MR-2900 terminal boards.
AWG
Length
14
7 620m (25 000 ft)
16
4 846m (15 900 ft)
18
3048m (10 000 ft)
22
1524m (5 000 ft)
Figure 11: Normally Closed Wiring
Figure 12: Normally Open Wiring
Figure 13: Addressable Style 4(Class B)
Wiring
