Zones
3 Installation Procedure
The PDRP-1001 PN 50734:C 03/11/99 17
4-Wire Smoke Detector Connections
Refer to the Device Compatibility Document for suitable 4-wire smoke detectors.
Figure 5 Diagram of Connections for a 4-Wire Smoke Detector
Notes on Class A (Style D) and Class B (Style B) field wiring:
1) The Power Supervision Relay coil leads must be connected to the last detector
base 24V screw terminals.
2) Calculation of the maximum allowable resistance in the 24VDC detector power
wiring:
R
MAX
= (20.6 - V
OM
)
_________________________________________________________________________________________
(N x I
S
) + (N
A
x I
A
) + (I
R
)
Where:
R
MAX
is the maximum resistance of the 24V wires.
V
OM
is the minimum operating voltage of the detector or end-of-line relay, whichever is
greater, in volts.
N
is the total number of detectors on the 24V supply loop.
I
S
is the detector current standby.
N
A
is the number of detectors on the 24V power loop which must function at the same
time in alarm.
I
A
is the detector current in alarm.
I
R
is the end-of-line relay current.
A maximum of 200mA is available from the +24VDC
4-wire smoke detector power circuit on TB1 terminals 3
and 4. Any power that is drawn from the +24VDC Non-
resettable Power on TB2 terminals 1 and 2 must be
subtracted from available 4-wire detector power. (See
“Specifications” and “Power” sections.)
Initiating Device Circuits 1,2,3, or 4
can be used. Class A (Style D) wiring
can also be employed.
UL listed 24 VDC
Four-wire Smoke Detectors
UL listed
4.7K, 1/2-Watt
ELR
Listed
Power
Supervision
Relay
Red
Black
24 VDC (+)
Common (-)
IDC (+)
IDC (-)
24 VDC (+)
Common (-)
IDC (+)
IDC (-)
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