Fire Alarm & BMS Wiring for FPS Generator Dry Contacts – South-Tek Systems

Applies to: South-Tek Systems N2-BLAST® FPS-series fire protection nitrogen generators — FPS-500, FPS-900, FPS-1650, FPS-3250, FPS-5000, FPS-10000, FPS-16500 and FPS-22500. The alarm relays share one terminal mapping across the whole line. What contacts a given unit provides does not — see the table below.

This article explains how to wire the dry contact alarm outputs on an FPS generator to a fire alarm panel, a BMS, or a monitoring panel, and how to prove the wiring before turnover. It is the reference the model articles point at for contact behaviour.

FPS generator dry contact wiring to a fire alarm panel or BMS

⚠ Warning — land by terminal number and state, then prove it by tripping the condition Land these contacts by terminal number and state, not by N.O./N.C. name. The same alarm relay is used across the FPS line, and its contact terminals are labelled 11, 12, and 14 on every model. Terminal 11 is the common. With the alarm active, 11-12 is held closed and 11-14 is open. That is the same on every contact and every family. The one exception is the purity contact on the FPS-1650, FPS-3250 and FPS-5000, whose terminals are not marked — identify and prove that one at the unit. Do not translate any of it into “normally open” or “normally closed” first; the naming varies with how the relay is driven, and a contact landed from the wrong assumption gives you supervision that reads backwards — healthy when the unit is in alarm, and in alarm when it is healthy. Then prove it: trip the condition and confirm what arrives at the panel before turnover — and note that tripping any of these conditions is a fire protection impairment, handled as set out under Proving the wiring before turnover.

What a dry contact is on this equipment

These are voltage-free relay contacts. They supply no voltage of their own — the receiving system provides its own control voltage, and the contact simply makes or breaks that circuit. Never apply external voltage directly to the generator's alarm terminals.

Each alarm relay gives you a common terminal and two switched terminals: one that is open in normal operation and closes on alarm, and one that is closed in normal operation and opens on alarm. On every FPS model, terminal 11 is the common, terminal 12 closes on alarm, and terminal 14 opens on alarm On the FPS-500 and FPS-900 the customer connection presents as three flying leads, so the lead colours give you the same mapping: 11 is the common (black lead), 12 is the contact that closes on alarm (red), and 14 is the contact that opens on alarm (blue). Prove it by tripping the condition before you rely on it.

What contacts your unit actually has

This is not the same across the line, and it changes how many points a contractor needs to pull.

Model family	Contacts provided
FPS-500 FPS-900	One common alarm contact, on both models — the terminals are provided on the unit and the customer connection to them is what is optional, so look for the CUST. CONN 11 / 12 / 14 leads before you assume a point is missing. It pools bypass, BlastOff®, filter, and power loss — there is no separate contact per alarm on this family, so the panel sees “an alarm” without knowing which. The controller display is what identifies it. These are the only FPS models that report loss of supply on a generator contact — power loss is one of the four pooled conditions, so a dead generator raises the panel here and nowhere else in the line. Alarm active: 11-12 closed, 11-14 open.
FPS-1650 FPS-3250 FPS-5000	A common alarm contact, a separate automatic bypass alarm relay, and a purity contact where the oxygen sensor is fitted. The common alarm pools everything except bypass — nitrogen pressure, purity, BlastOff®, and equipment status all drive it. Bypass reports on its own relay only, so a unit monitored on the common contact alone will never tell the panel it has gone to bypass air — pull that point. Alarm active on both: 11-12 closed, 11-14 open, but they land on different terminals, so identify each pair at the unit. There is no power loss contact on this family, and power loss is not pooled onto the common alarm — read the warning below before you price the points. The purity contact's terminals are not marked: identify it on the unit and prove it from Maintenance → Alarm Contacts, which is an impairment like any other forced contact.
FPS-10000 FPS-16500 FPS-22500	Two relays, labelled COMMON ALARM and BYPASS ALARM in the cabinet. Both present the same 11 / 12 / 14 terminals, so do not rely on the label alone: toggle each contact one at a time and have someone at the panel tell you which point moved. Two relays swapped for each other annunciate perfectly and report the wrong condition for the life of the installation. Four conditions drive the common alarm — nitrogen pressure, purity, BlastOff®, and equipment status, which here covers the external feed compressor and the internal dryer. A filter alarm is not one of them — the unit keeps running and filter status shows at the controller only. Bypass reports on its own relay only — pull that point. It is also automatic: it engages and clears on its own, so land it on a latching input or a real episode of air in the riser will come and go unseen. No separate purity contact: purity drives the common alarm where the oxygen sensor is fitted. No power loss contact either, and power loss is not pooled onto the common alarm — read the warning below before you price the points. Alarm active: 11-12 closed, 11-14 open.
Other FPS models	The terminal states and procedures in this article are written for the FPS-500, FPS-900, FPS-1650, FPS-3250, FPS-5000, FPS-10000, FPS-16500 and FPS-22500. On any other model, confirm the available points against the schematic supplied with the unit, or ask South-Tek with the serial number, before pulling wire.

⚠ Warning — only the FPS-500 and FPS-900 report loss of supply On the FPS-500 and FPS-900, loss of supply is one of the conditions pooled onto the single common alarm contact, so a dead generator raises the panel. On every other family — FPS-1650, FPS-3250, FPS-5000, FPS-10000, FPS-16500 and FPS-22500 — there is no power loss contact. Those families carry a common alarm and a separate automatic bypass alarm instead, and a generator that has lost supply will not annunciate through either: the panel keeps reading healthy while nitrogen makeup to the riser has stopped. Where loss-of-power detection is required on those families, the fire alarm or BMS contractor must supervise the generator's branch circuit as a separate panel point. Raise it at design stage — it is a point on the panel and a run in the conduit schedule, and it cannot be added off the generator afterwards.

Terminal states — what closes when

This is the table to wire from, and it governs. Do not re-derive it from an N.O./N.C. marking or from your own reading of a relay's rest position. Prove every point by tripping the condition and watching what arrives at the panel before turnover.

Contact	Healthy / normal	Alarm active
Common alarm every model covered by this article	11-14 closed 11-12 open	11-12 closed 11-14 open
Automatic bypass every family except FPS-500 / FPS-900	11-14 closed 11-12 open	11-12 closed 11-14 open
Purity FPS-1650 / 3250 / 5000 only, where the oxygen sensor is fitted	Terminals not marked. Identify it on the unit and prove it from Maintenance → Alarm Contacts before relying on it — an impairment, handled like any other forced contact. No separate purity contact exists on the other families; there, purity drives the common alarm.
Loss of supply every family except FPS-500 / FPS-900	No contact, and not pooled onto the common alarm. A generator that has lost supply reads healthy at the panel on every relay it has. Supervise the generator's branch circuit as a separate panel point where loss-of-power detection is required. On the FPS-500 and FPS-900 it is pooled onto the common alarm instead.

Land 11-14 if you want the conductor supervised — it is closed while healthy, so a cut or disconnected conductor reads as an alarm at the panel rather than as silence. That is conductor supervision, not fail-safe operation. On every family except the FPS-500 and FPS-900 the relay coils sit de-energized while healthy, so a generator with no power presents the same 11-14 closed state as a healthy one. No choice of pair changes that — only a separately supervised branch circuit does.

Choosing which side to land on

Which pair you use is a design decision that belongs to the fire alarm or BMS contractor, not to this article:

On every family except the FPS-500 and FPS-900, budget a branch-circuit supervision point. There is no loss-of-power contact on the generator and power loss does not reach the common alarm, so loss of supply is invisible to the panel unless the branch circuit is supervised separately. Decide at design stage whether the site requires it, and allow the point and the run for it.
Fire alarm panel. The panel and module type determine it. Most supervised inputs use an end-of-line resistor with the contact arranged to change the loop state on alarm, so the required contact form depends on the module. Ask the fire alarm contractor which form their module needs before you land anything, and confirm with the authority having jurisdiction where the annunciation matters.
BMS / BAS. Usually a non-supervised input where a closure on alarm is all that is wanted — but confirm against the input card rather than assuming.
Either way, record it. Write down which terminals you landed, which contact form was chosen and why, and the result of the function test. The next technician has no way to work any of that out from the outside.

Analog outputs

Beyond the dry contacts, FPS generators can also export live readings for trending. Receiving equipment is installed by others.

Model family	Analog output
FPS-500 / FPS-900	An optional user-configurable 4–20 mA output — ambient temperature as standard, or oxygen percent, trace O₂ in PPM, or supply pressure where those sensors are fitted. Get the engineering-unit range for the signal you selected — what value corresponds to 4 mA and to 20 mA — from South-Tek Service against the serial number before you trend it.
FPS-1650 / 3250 / 5000	Two outputs — tank pressure, and tank trace O₂ in PPM (the second reads only where the oxygen sensor is fitted). Both are 0–10 V, the same across all three models. The engineering-unit range is not printed on the schematic. Get it from South-Tek Service against the serial number — what value corresponds to 0 V and to 10 V on each output — and scale the receiving equipment to that range before you trend anything. It follows the sensor calibration, so it is one of the few figures here that is specific to your machine. Do not carry a range over from another job. Note the optional dew point monitor is 4–20 mA, a different signal type on the same machine.
FPS-10000 / 16500 / 22500	No analog output is assigned on this family. The controller has analog output terminals, but no signal and no engineering-unit range is published against them. Do not design an analog trend for these models without confirming the available outputs and their ranges with South-Tek Service first — have the serial number to hand when you call. The route for live readings on this family is Modbus TCP/IP, covered under Digital integration below. The controller also graphs and logs tank pressure and the optional sensors on its own screens.

▲ Attention — check the signal type before wiring A 0–10 V output landed on a 4–20 mA input reads zero, and the customer's trend graph is a flat line nobody notices for months. The two signal types sit on the same machine: on the FPS-1650, FPS-3250, and FPS-5000 the tank pressure and trace O₂ outputs are 0–10 V while the optional dew point monitor is 4–20 mA. On the FPS-500 and FPS-900 the single configurable output is 4–20 mA. Match each input card to the output it is actually reading. This applies to the FPS-500, FPS-900, FPS-1650, FPS-3250 and FPS-5000 only — the FPS-10000, FPS-16500 and FPS-22500 have no published analog output to match an input card to.

Proving the wiring before turnover

Wiring that has never been tripped end to end is wiring nobody has checked. Test every point you landed, and have someone at the receiving panel confirm it arrived.

⚠ Warning — testing these contacts is a fire protection impairment For the length of the test the generator's supervisory signals are not trustworthy. Stopping the unit or closing the nitrogen outlet valve stops nitrogen makeup to the riser, and putting the riser on compressed air suspends corrosion protection. Losing makeup is the more urgent of the two: if the riser leaks while makeup is stopped, the storage tank may not be able to hold supervisory pressure, and on a dry-pipe system a sufficient loss trips the dry-pipe valve and puts water in the pipe. Before you start: notify the building owner or their impairment coordinator and the alarm monitoring company, have the affected points put on test, tag the system under the site's impairment program, and record the riser's supervisory pressure — it is the only figure that lets you prove at the end that you put the riser back where you found it. Ask the impairment coordinator whether the site's program sets a duration limit or requires a fire watch. Keep the window to the length of the work, and stop and restore makeup immediately if riser pressure falls. Every test below ends with the restore-and-verify list after the table.

Controller	How to trip the contact
Touchscreen FPS-1650, FPS-3250, FPS-5000	Maintenance → Alarm Contacts toggles the purity and common alarm contacts and the local buzzer individually, which proves point mapping rather than just continuity. It does not cover bypass: that is exercised from Maintenance → Valve Controls (Automatic BYPASS) with the unit Stopped and the nitrogen outlet valve closed first, every valve returned to Off before restart. Closing that valve stops nitrogen makeup, and bypass puts compressed air in the riser — each an impairment on its own. That is a fire protection impairment: notify the building owner or their impairment coordinator and the alarm monitoring company, put the affected points on test, and tag the system before you start. There is no power loss point on this family. Before you leave: every toggle and valve back to normal, the nitrogen outlet valve reopened slowly, the unit off bypass and back on nitrogen in Run or Standby, the panel clear, the riser back at the pressure you recorded, points off test, tag cleared.
Black rectangular controller FPS-500, FPS-900	The BlastOff® simulation below does not apply to legacy units with the square green-display controller — see Resetting the Filter Alarm — Legacy Panasonic Controllers. There is no Alarm Contacts screen on this controller. Use the BlastOff® simulation instead: hold SET for about 7 seconds until the passcode screen appears, press SET once to begin entry, enter 6557 with the plus and minus keys, and confirm with ENT. On the HOLD SET screen, hold SET for about 5 seconds. The unit simulates a BlastOff® alarm: the dry contact trips for roughly 2 seconds, and the audible buzzer sounds with it. That puts a real alarm on the customer's monitoring account. That is a fire protection impairment: notify the building owner or their impairment coordinator and the alarm monitoring company, put the affected points on test, and tag the system before you start. Warn anyone in earshot first — a technician on a ladder at the riser will not be expecting the buzzer. Afterwards confirm the contact has released, the controller is not still showing BlastOff®, and the panel has cleared; then take the point off test and clear the tag. If it is still showing BlastOff®, treat it as a genuine alarm: find the cause first, then power cycle to reset. To prove the bypass condition instead, turn the 3-way outlet / bypass valve on the lower left of the cabinet to Bypass Mode and confirm what arrives at the panel; the alarm clears when the handle is back in the Nitrogen Out position. That puts compressed air into the riser. That is a fire protection impairment: notify the building owner or their impairment coordinator and the alarm monitoring company, put the affected points on test, and tag the system before you start. Before you leave: handle back in the Nitrogen Out position, the Air n2 bypass alarm cleared, the panel clear, and the riser back at the pressure you recorded.
Touchscreen FPS-10000, FPS-16500, FPS-22500	First, confirm on the Alarm Settings screens that every condition you are relying on is switched On — nitrogen pressure, BlastOff®, and the compressor and dryer contacts can each be turned off there, and a condition turned off reads healthy at the panel for as long as it stays off. Confirm the Automatic Bypass System is On as well: that screen can disable bypass outright, not just its annunciation. Record what was enabled at turnover. Maintenance → Alarm Contacts toggles each contact and the audible individually. Both contacts — common alarm and bypass — are proved from this screen, so no valve has to be closed and no air enters the riser. Toggle one at a time and have someone at the panel tell you which point moved. Warn everyone at the unit and the riser before you toggle the audible. That is a fire protection impairment: notify the building owner or their impairment coordinator and the alarm monitoring company, put the affected points on test, and tag the system before you start. Only exercise the bypass valve if the changeover itself must be demonstrated — from Maintenance → Valve Controls, unit Stopped, the ½" N2 OUT ball valve closed first, every valve back to Off before restart. There are two ½" ball valves on the interior right-hand wall, reached through the front doors, one above the other about 6" apart: N2 OUT is the lower one, AIR INPUT is above it. Closed is handle perpendicular to the stem. Read the label — never work it out by position. Closing it stops nitrogen makeup and is an impairment on its own. There is no power loss point on this family; where the branch circuit is supervised separately, test it at the panel end, on test, not by killing the generator. Do not use a BlastOff® alarm as a test — clearing one needs the leak resolved and a power cycle. Before you leave: every toggle and valve back to normal, the N2 OUT valve reopened slowly, the unit restarted to Run or Standby, every alarm condition switched back on, the panel clear, the riser back at the pressure you recorded, points off test, tag cleared.

⚠ Warning — restore and verify before you leave Do not leave the site until every one of these is confirmed: every forced contact and buzzer toggle back to normal; every valve on the Valve Controls screen returned to Off and the nitrogen outlet valve reopened slowly, or on the FPS-500 and FPS-900 the 3-way outlet / bypass valve back in the Nitrogen Out position with the Air n2 bypass alarm cleared; every conductor landed and secured and nothing loose in the panel; the cabinet doors closed and latched; supply power restored and the generator running or in Standby; every alarm condition you switched off or muted switched back on; the receiving panel showing no active alarm or trouble from the generator; the riser back at the supervisory pressure you recorded, read at the riser's own gauge or at the panel — not from the generator's tank pressure, which sits upstream of the outlet valve and proves nothing about the riser; the points off test with the alarm monitoring company; and the tag cleared with everyone you notified. Record the terminals, the contact form chosen, and the test result on the commissioning paperwork.

⚠ Warning — ordinary service disturbs these contacts too The same impairment handling applies outside commissioning. Opening the disconnect stops nitrogen makeup to the riser. On the FPS-500 and FPS-900 it raises the common alarm; on every other family it raises nothing at all, so the impairment notification is the only thing telling anyone the supervision is degraded. Declare it, notify the building owner or their impairment coordinator and the alarm monitoring company, tag the system, and before you leave restore power, confirm the unit returns to Run or Standby, confirm the panel has cleared, confirm the riser is back at the pressure you recorded, and clear the tag. On the FPS-500 and FPS-900 the filter timer reset pulses the common alarm contact for about a second — that is an impairment too: notify both parties before you press it, tag the system, and confirm the panel is back to normal and the tag cleared afterwards. On the FPS-10000, FPS-16500 and FPS-22500 the impairment notification is the only thing telling anyone the supervision is degraded — the generator simply stops making nitrogen while the riser keeps reading healthy. Confirm the unit is back in Run or Standby and the riser back at the supervisory pressure you recorded before you clear the tag.

⚠ Warning — landing these contacts is electrical work inside a live control panel Disconnect the generator from its supply power, lock it out, and prove the terminals dead before you land a conductor. The alarm terminals share a control panel with line-voltage field wiring on every family, and a breaker or power entry module on the cabinet is over-current protection, not a disconnecting means — opening it leaves the line side and the customer terminals energized. Identify the disconnecting means for the unit in front of you and prove the terminals dead; do not assume a switch on the cabinet has isolated anything. Opening the disconnect stops nitrogen makeup to the riser, so it is itself an impairment: notify the building owner or their impairment coordinator and the alarm monitoring company, tag the system, then restore power, confirm Run or Standby, confirm the panel is clear, and clear the tag before you leave. If any of the work has to be done with the unit running, wear safety glasses while the cabinet door is open and ear protection while it runs.

What to pull, and what to land on

Three conductors per contact if you want both sides available at the panel, or two if the contact form is already settled. Decide before rough-in — adding the third conductor later means pulling the run again.
Do not switch a load on these contacts. They are alarm-signalling contacts for a supervised panel input or a BMS point — no contactor coils, no sounders, no lamps. If the design needs to switch anything beyond a panel input, get the contact rating from South-Tek Service with the serial number before you land it. No contact rating is published for these relays on any family, so this is a call rather than a lookup.
16–22 AWG for the signal run on the FPS-1650, FPS-3250 and FPS-5000. Follow normal low-voltage practice otherwise — separation from power conductors, and end-of-line resistor placement per the fire alarm contractor's design. On the FPS-10000, FPS-16500 and FPS-22500 no signal-run gauge is published: size it to the panel manufacturer's requirement for the input, and note that the terminal blocks accept 26–12 AWG, so any normal low-voltage signal conductor will land — that is a clamping range, not a sizing recommendation, so size to the panel manufacturer's requirement. Keep the run clear of the 110/220 VAC conductors inside the cabinet. Hold at least 3" between the signal run and any 110/220 VAC conductor inside this cabinet, and cross them at right angles where they must meet. Confirm where the signal run enters the cabinet before the walls close. The only entry designated on this family is the ½" conduit hole for the customer's main power connection, so agree a separate signal entry with South-Tek rather than sharing it — have the serial number to hand.
On every family except the FPS-500 and FPS-900, one extra run and one extra panel point for branch-circuit supervision, where the site requires loss-of-power detection. Nothing on the generator reports loss of supply and it cannot be added off the generator later, so pull it at rough-in.
Where a remote stop switch was ordered, it is wired by others and needs its own run. Allow for it at the same time.
Where a ferrite core is called for on a field run, install it within 2" of the terminal with the conductor wrapped at least twice. It is an approval condition, not a suggestion.
Signal conduit is a rough-in item. Confirm the terminal location and cable entry on the unit — or on the schematic in the installation package — before the walls close.

Digital integration

Dry contacts are not the only route to a BMS. FPS-500 and FPS-900: Modbus RTU over RS-485 is the integration route on this family, available as an option. Design the head end for RTU at the unit. If a project cannot work without Ethernet or Modbus TCP, raise it with South-Tek before you commit to the architecture. FPS-1650, FPS-3250 and FPS-5000: the touchscreen controller supports Ethernet and Modbus TCP/IP where the Ethernet card is fitted — the controller's Ethernet status screen reports Ethernet Card Exists, so confirm it there and set the network parameters before you commission the integration. FPS-10000, FPS-16500 and FPS-22500: the touchscreen controller supports Ethernet and Modbus TCP/IP where the Ethernet card is fitted, alongside remote access and SD card access on the same connection. It needs a static IP assigned to the controller and entered at the controller; a connection inside the organisation's own network does not need a subnet or gateway. Confirm the card is present and check traffic on the controller's Network Communications Status screen, then press the connect button to establish the connection. Prefer the connect button. A power cycle stops the generator and makes its supervisory signals untrustworthy while it restarts, so if one is needed, treat it as an impairment — declare it, notify the building owner or their impairment coordinator and the alarm monitoring company, tag the system, and before you leave confirm the controller has restarted with its static IP retained, the unit is back in Run or Standby, the panel shows no active alarm or trouble from the generator, and the riser is back at the supervisory pressure you recorded. This is the route to use for live readings on this family, since it has no published analog output. Detail: Modbus Communication – FPS Nitrogen Generator.

Important notes

Do not apply external voltage directly to the generator's alarm terminals. The receiving system supplies the control voltage.
All wiring must comply with local electrical and fire codes, and the choice of contact form must be coordinated with the fire alarm or BMS contractor and the authority having jurisdiction.
Generator alarms are supervisory signals. They report the condition of the nitrogen system — they are not life-safety trip signals, and must never be wired in a way that interferes with the operation of the fire alarm or sprinkler system.
Record the terminals used, the contact form chosen — which of the 11-12 / 11-14 pairs you landed — and the result of the function test on the commissioning paperwork.

Need help? South-Tek Systems Service — Phone: (910) 415-1880 · Open a support ticket at support@southteksystems911.zendesk.com or through the Help Center. For confirmation of alarm point assignments or a wiring diagram for a specific unit, have the serial number to hand.

Related to