Wiring Considerations - Honeywell CM4 Technical Handbook

CM4 Four-Point Continuous Monitor

10.2.2 Wiring Considerations

WARNING
Removal of the cover over the Input/Output Module may expose
hazardous voltages that are still present with power removed from the
CM4 monitor. Ensure all wiring installation is performed by qualified
personnel following all national and local electrical codes.
NOTE:
Units equipped with L
module.
A major consideration in any remote application is the reduction of
electrical interferences such as RFI or other electrical noise. Follow
the guidelines below when choosing the wire and routing path for your
remote reset switch location.
1. External wires should be either shielded twisted pair or
individually shielded wires and should be rated at 600V for
isolation. The remote alarm reset contacts draw approximately
25 mA/pt (100 mA for all four points). The loop resistance (wire
and switch contact resistance) should be 2000 ohms per point
maximum.
2. Do not run the alarm circuit wiring in the same conduit with
wiring for inductive loads such as motor controls or AC loads
and lines.
3. Use switches designed for low current applications, with
normally open, momentary close contacts.
4. The back panel of the CM4 has been designed to allow low
voltage wiring to exit from the unit from the right side (as you
view the back panel) while higher voltage and AC wiring exits
on the left. Keeping this wiring protocol reduces the risk of
electrical noise causing interference to your alarm circuit. The
remote inputs are located at the lower right of the relay panel
as shown below.
CM4 Technical Manual
W do not require an Input/Output
on orks
10.2.3 Using an External Power Supply
The recommended method of wiring the remote alarm reset circuit
is using an external (user-supplied) 24 VDC power supply. Using the
external power supply provides a very efficient method of powering
the alarm reset circuit, and reduces the risk of electrical interference
within the CM4 monitor. A schematic of the circuit is shown in Figure
10-1.
PT. 1
T.B.
15
Figure 10-1: CM4 Circuit Schematic
10.2.4 Using the CM4 Monitor's Internal Power Supply
Another method of installing the remote alarm reset circuit utilizes the
24 VDC supply available from the CM4 monitor. While this method is
usable for many applications, there are limitations to consider.
CAUTION
To ensure the CM4 monitor operates correctly, avoid EMI and RFI
coupling circuits to the unit. Follow these guidelines when wiring
external circuits:
• Do not connect the negative side of the remote reset terminal to
building ground.
• Do not install wiring in the same conduit with any other circuitry.
• If properly grounded conduit is not used, a twisted pair shielded cable
with the proper shield grounding techniques utilized must be used.
10-3
24 VDC
+/– 10%
@ 100 mA
PT. 2 PT. 3 PT. 4
T.B. T.B.
16 17
T.B.
18