521LX and 521LXT Addressable Smoke Detectors

Installation Sheet
521LX and 521LXT Addressable Smoke Detectors
The Model 521LX and 521LXT Smoke Detectors are the industry’s finest smoke detectors, with analog features
such as remote maintenance reporting (CleanMe™), drift compensation, and multi-criteria detection. These smoke
detectors incorporate an addressable single-point module for connection to the Keypad bus or LX-Bus™ of
XR100/XR500, and XR150/XR350/XR550 Series panels. The 521LXT also includes multi-criteria fast response heat
sensor algorithms for a broad range of fire detection.
Single Point Addressable
Incorporated is a factory mounted, addressable single-point zone expander on the back of the smoke detector. The
included 4-wire harness allows a direct connection to the Keypad bus or LX-Bus of XR100/XR500, and XR150/XR350/
XR550 Series panels. The integrated zone expander reports smoke detector alarm and service conditions to the panel
as a single zone. A TXD LED is also included, which flashes to confirm device polling.
CleanMe™ Remote Maintenance/Trouble Reporting Feature
These detectors have a unique feature that allows a service signal to be sent to the panel when the smoke detector
has drifted outside UL sensitivity ranges or a hardware fault exists. In most cases, the signal is the result of the
detector becoming dirty over time and, as a result, has become oversensitive. This condition could result in a false
alarm. The CleanMe™ signal enables the panel to receive a service signal allowing an installer time to clean the
detector by replacing the inexpensive optical chamber with a new DMP Model 525. This service information can be
transmitted to the central station.
Self-Diagnostics with Automatic Sensitivity Testing
Each photoelectric smoke detector monitors its own sen­sitivity and operational status. Once a day, and immediately
upon first power up, the detector performs a full diagnostic test that includes a sensing chamber and internal
electronics dy­namic test. If the detector drifts out of its sensitivity range or fails internal diagnostics, the alarm LED
flashes once every second to indicate trouble. This meets NFPA 72 field sensitivity testing requirements without the
need for external meters.
Built-In Drift Compensation
The detector is the industry’s first addressable smoke detector with built-in drift compensation. Automatically
adjusts sensitivity, up to a maximum of 1.0%/ft., as it becomes dirty. This feature increases immunity to dust and
dirt by 30 to 50%.
Consult the Local Authority Having Jurisdiction (AHJ) and NFPA 72 for specific installation information regarding
smoke detector spacing, placement, and special applications.
The detector wires directly to the panel 4-wire Keypad bus or LX-Bus. See Compatible LX-Bus Interface Cards.
When wired to the LX-Bus, the detector uses only one of the available expansion zone numbers allowing the
assignment of additional zone expanders to the next zone number address. See Addressing the 521LX and LXT.
When the head must lock to the base, simply break away the
locking tab and the knock out for the screwdriver slot with a pair
of pliers. To remove the detector head, insert a small screw­
driver through the slot at the side of the base and press in while
simulta­neously turning the detector head counterclockwise.
See Figure 1.
To lock the 521 to the mounting
base, use pliers to break off the
locking tab on the base tab
the breakaway tab for the
screwdriver slot on the 521.
Locking the Detector
Each detector head is equipped with a breakaway locking tab slot
to prevent unauthorized detector head removal. For installations
where unauthorized removal of the detector head is not a
concern, such as high ceilings, no action is required. Remove the
head by simply turning counterclockwise.
Figure 1: Locking Mount on 521LX/521LXT
Installing the Mounting Base
The included mounting base makes the smoke detector easy to install and remove if necessary. The detector head
simply twists off of its 4.75” mounting base.
The mounting base connects directly to standard single-gang electri­cal boxes, 3-inch round, or
4-inch octagonal boxes. The base may also be mounted without electrical boxes if approved
by the AHJ or if codes allow.
Mounting the Detector Head
To install a detector head, simply line up the raised marking on the
side of the detector with the arrow on the mounting base. Insert
the head and rotate it clockwise approximately 15 degrees to snap
the locking tab into place. See Figure 2.
Locking Tab
Removing the Detector Head
To remove the detector head, simply turn counterclockwise. If
the locking tab slot is removed, insert a small screw­driver into
the locking tab slot on the side of the base and press in while
simultaneously turning the detector head counterclockwise as
shown in Figure 2.
Figure 2: Installing the
521LX/521LXT on the Base
Black (common)
Green (data)
Yellow (data)
Red (Smoke power)
0 1
7 8
5 6
Bottom View
May Require an
Interface Card
Figure 3: 521LX/LXT Wiring
0 1
7 8
5 6
7 8
0 1
5 6
Testing Each Detector
Module rotary
switches set for
zone address 569
Addressing requires setting two on-board rotary switches to match
the LX-Bus zone number address. Set the switches to match the
last two zone number digits. For example, on an XR500 panel,
to assign the detector to zone number 569 on LX-Bus 1, set the
left rotary switch (labeled TENS) to 6 and the right rotary switch
(labeled ONES) to 9, as shown in Figure 4. To assign to zone number
623 on LX-Bus 2, set the left rotary switch to 2 and the right rotary
switch to 3.
0 1
5 6
7 8
Addressing the 521LX and LXT
First, pull wire through electrical box, then through the mounting
base center opening. Connect the 4-wire harness to the J1 terminal
according to the wiring diagram in Figure 3.
All 521LX and 521LXT smoke detectors ship with a plastic dust
Figure 4: Address switches
cover for use in areas where construction is continuous. Smoke
detectors do not work with the dust cover in place. Remove the
dust cover after installation is completed and, prior to testing. Also, disconnect alarm notification appliances,
releasing service devices, and extinguish­ing systems prior to performing detector tests. Be sure to reconnect all
devices at testing conclusion.
Per NFPA 72, “all smoke detectors shall be tested in place annually, to ensure smoke entry into the sensing chamber
and alarm response. Testing with smoke or listed aerosol acceptable to the manufacturer, shall be permitted.”
Annual functional testing is best accomplished using Smoke! In a can, Model 526, available from DMP. Carefully
follow the directions on the can.
The detector performs a smoke test every nine seconds while its LED flashes. If smoke is detected, the rate of
sampling increases to every 4.5 seconds. Excessive smoke must be detected in three con­secutive tests for the alarm
to sound. Therefore, when testing the detector with smoldering punks or cotton wicks, hold the smoke source near
the opening for smoke entry and gently direct smoke into the detector for 20 seconds or until an alarm is indicated.
Snap into
Testing the detector with Smoke! In a Can or with a smoking
punk only serves as a simple go/no go test. If the test is
successful, the LED remains lit. For in-depth sensitivity testing
see Sensitivity Level Test Mode.
If testing is unsuccessful, reset the detector by performing a
panel Sensor Reset. Snap off the detector cap by prying it loose
with a screwdriver placed in the slot in the base of the cap as
shown in Figure 5. Release the tabs on each side of the optical
chamber to remove the chamber. Then, blow or brush off the
optical block base and snap a new optical block chamber in
place, replace the cap and verify sensitivity with the Sensitivity
Level Test.
Model 525
Optical Block
Figure 5: 521LX/521LXT Optical Sensing Chamber
Digital Monitoring Products
521LX/521LXT Installation Sheet
Sensitivity Level Test Mode
Each smoke detector also includes a special sensitivity level test mode
activated by holding a magnet near the integral reed switch for more than
one second. See Figure 6. Once the routine starts, the alarm LED flashes
one to nine times, indicating actual sensitivity and whether or not service is
required. See the 521 Sensitivity Table.
After the sequence of blinks, if the sensitivity is found to be within limits and
if all other tests pass, the detector goes into alarm until reset by the panel.
If the sensitivity is not within limits, or an unser­viceable hardware fault is
detected, the alarm LED con­tinues to flash once per second until the detector
is reset by the panel. If the sensitivity test is not within guidelines, take
action as recommended in the 521 Sensitivity Table.
Obscuration (% ft.)
Figure 6: Sensitivity
Testing the 521LX/521LXT
Reset unit and re-run sensitivity test, if
indication remains the same, replace unit.
Detector is not sensitive enough.
Clean per instructions. Reset unit and re-run
sensitivity test, if indication remains the same,
replace unit.
Detector is within sensitivity
Detector is too sensitive.
Check to be sure optical block cover is snapped
down completely. Clean per instructions.
Table 1: 521 Sensitivity Table
Smoke Detector Dip Switches
If there are dip switches to the left of the screw terminals, they are factory preset and must not be changed.
Maintenance, Cleaning, and Sensitivity
The smoke detectors are designed for easy field service and maintenance. If a smoke detector drifts beyond its
approved sensitivity range for more than 24 hours or fails internal diagnostic tests during power-up, the unit
automatically indicates trouble by flashing its LED every second. Under normal conditions the LED flashes every nine
seconds. Therefore, a simple visual check of the LED status meets NFPA 72 field sensitivity testing requirements
without the need for external meters or ladders. In accordance with NFPA 72-7-3.2.1, smoke detector sensitivity
should be checked within one year after installation and every alternate year thereafter, in commercial installations,
or every three years in residential sites.
The photoelectric detector sensing chamber un­snaps for easy field cleaning and service. Whenever the status LED
indicates cleaning is necessary, remove the photoelectric detector cap, snap off and throw away the optical block.
Then blow or brush off the optical block base and snap a new optical block chamber back in place (see Figure 5),
replace the cap and verify sensitivity with the Sensitivity Level Test.
521LX/521LXT Installation Sheet
Digital Monitoring Products
Wiring Specifications
When planning an LX-Bus™ and keypad bus installation, keep in mind the following specifications:
1. DMP recommends using 18 or 22-gauge unshielded wire for all keypad and LX-Bus circuits. Do Not use
twisted pair or shielded wire for LX-Bus and keypad bus data circuits. To maintain auxiliary power integrity
when using 22-gauge wire do not exceed 500 feet. When using 18-gauge wire do not exceed 1,000 feet.
Install an additional power supply to increase the wire length or add devices.
2. Maximum distance for any one circuit (length of wire) is 2,500 feet regardless of the wire gauge. This
distance can be in the form of one long wire run or multiple branches with all wiring totaling no more than
2,500 feet. As wire distance from the panel increases, DC voltage on the wire decreases.
3. Maximum number of devices per 2,500 feet circuit is 40.
Note: Each panel allows a specific number of supervised keypads. Add additional keypads in the unsupervised
mode. Refer to the panel installation guide for the specific number of supervised keypads allowed.
4. Maximum voltage drop between the panel (or auxiliary power supply) and any device is 2.0 VDC. If the
voltage at any device is less than the required level, add an auxiliary power supply at the end of the circuit.
When voltage is too low, the devices cannot operate properly.
For additional information refer to the 710 Installation Sheet (LT-0310) and or the LX-Bus/Keypad Bus Wiring
Application Note (LT-2031).
521LXTPCB Replacement Smoke Detector
525 Replacement Optical Chamber
526 Smoke! in a Can™
CleanMe™ is a trademark of Sentrol, Inc.
Operating Range
Standby Current
Alarm Current
Maximum Ripple
Sensitivity Photoelectric
Operating Temperature
Operating Humidity Range
RFI Immunity
Heat Sensor (LXT Only)
Rate of Rise
Power Up Time
Drift Compensation
Detector Head Dimensions
Mounting Dimensions
8.8 to 15.0 VDC
10% (Vp-p) peak to peak
3.1% + 0.50 to 1.00%
32°F to 100°F
0 to 95% non-condensing
20V/m minimum; 0 to 1000MHz
15°F/min and > 105°F
15 seconds
1.0%/ft. max.
5” Diameter, 2” Height
4.75” Diameter, .3” Height
White Head and Base
2500 North Partnership Boulevard
Designed, Engineered and
Assembled in USA
Springfield, Missouri 65803-8877
California State Fire Marshal (CSFM)
FDNY COA #6167
UL 268 Smoke-Automatic Fire Detectors
LT-0403 1.01 © 2015 Digital Monitoring Products, Inc.
Download PDF