Post Indicator Valve with Fire Department Connection
A common task when installing a new fire alarm system is undergrounds. Typically when a C-16 or fire protection (fire sprinkler) contractor installs their incoming lines they will at the same time install the necessary fire alarm underground conduits for the connections to the backflow prevention switches (OS&Y Outside Screw and Yoke) or PIV (Post Indicator Valve) switches. However, sometimes this task could be a part of the fire alarm contractor's scope of work. If you find yourself installing underground conduit or direct burial cable make sure to follow all of the national codes and regulations.
Direct Burial Cable as an Alternate to Conduit
Backfloe Preventor with OS$Y Switches for Fire Alarm
Some contractor's may choose to use direct burial cable also referred to as UF Cable commonly identified by its grey coating. Direct burial fire alarm cable not protected in conduit must be installed at a depth of 24" below grade with either schedule 80 PVC or Rigid conduit stubs up to your box. When fire alarm cable is installed within plastic conduit it must be 18" deep and installed with schedule 80 PVC. This is a more durable plastic conduit (grey color) than the common household irrigation lines. The best way to install these conduits or cable is with a Ditch Witch. Simply set the depth and go.
Junction boxes that are run out into the middle of a remote area without an anchor point must have the schedule 80 PVC embedded in the concrete to support the box. Another method is to attach the box to a post that is either driven or buried in the ground 18" and connects directly to the schedule 80 PVC conduit. Junction boxes should be installed at least 12" above grade but not more than 18" for the unattached method.
Are the new Wheelock LED Series Notification Appliances all They're Cracked up to be?
Although the Wheelock LED (Light Emitting Diode) notification appliances are not so new anymore, they still seem to bring up quite the conversations. Like any new fire alarm equipment, it is wise to let them prove themselves before you actively start specifying and installing them throughout all of your sites. Well that time has come and gone as these LED strobes and horn/strobes have been flying off the shelves.
Our goal here is to make you aware of their capabilities so that you can decide when and when not to include them in your fire alarm system design criteria. For this comparison I am going to be using the new Wheelock LED Series Horn/Strobe (model LHS) and the Older Wheelock Exceder Series Horn/Strobe (model HS). Note that both models comparisons will be based off wall mounting, 24 VDC, 3 Tone Temporal Output, and set at the High Setting. This should keep everything fair for the sake of the article.
Lets take a look at differences and similarities of the two notification appliances.
As you will notice from the chart I created above, the two notification appliances have quite a few differences. One of the more noticeable differences is the candela selection available. You can see that the Exceder series covers standard candela all the way up to high candela at 185 CD. On the other hand the Wheelock LED series appliance only covers the standard candela range.
Now the biggest item that everyone is discussing around the new LED series strobes is the lower current draw. We all know the lower the current draw, the more appliances we can fit on a circuit. More appliances on circuits results in few circuits, and less remote power supplies. As you may notice in the "Current Draw" tables above, the LED series appliances have a lower current draw through the range of 15 CD - 75 CD. Once you jump up to 110 candela, the standard Exceder series with Xenon bulb actually draws less.
It all depends on you application as your facility may demand more 110 candela strobes in comparison to your lower levels (15-75). In this case you would probably want to stay with the older Exceder Xenon bulb technology. Now if you have an office building with multiple corridors, you can get away with 15 candela and the LED strobes would be your best bet.
*It is also very important that I make you aware that Cooper-Wheelock has made it clear that both the Xenon bulb and LED style visual appliances are compatible on the same circuits and will successfully SYNC if you use the proper remote power supply or sync module such as the DSM-12/24.
I hope this information assists you in your design as both models are great products with their own special characteristics.
How do you mark the devices that need a return service trip to correct?
When you are performing a fire alarm system test or fire alarm system pre test, make sure to check every fire alarm device and notification appliance. This includes audible visual, smoke detectors, heat detectors, pull stations, Ansul (hood systems), door holders, and the one everyone skips, duct smoke detectors.
When checking these devices it may become a burden to write down the exact location of a fire alarm device or appliance that did not function correctly. This really applies to non addressable devices as these devices have a location/description programmed into the fire alarm control panel. Devices such as conventional initiating devices, strobes, horns and speakers are harder to keep track of.
Here is a little trick that will help shave time off your fire alarm test. Use small bright yellow colored stickers to mark the fire alarm devices or appliances that did not function correctly. This will make it easy to come back and check or note deficiencies.
With door holders, you can mark the actual magnetic holder if it did not release, or you can mark the hardware mounted on the door if the door did not close and latch. It makes it easy to come back and accurately make notes on your fire alarm test form otherwise know as the NFPA 72 testing and inspection sheets or the Record of Completion if a new system.
You can also get creative and use different colors for different scenarios. For example, lets say you have a duct smoke detector that went into alarm but did not shut down the air. Use a green sticker for HVAC shutdown.
Try it out and let us know what you think.
Make sure to join our Fire Alarms Online Facebook Group HERE.
Elevator shunt trip is one of the most frequently misunderstood elevator and fire alarm interfaces. In simple terms, elevator shunt trip is used to remove operating power from an elevator before sprinkler water can be discharged onto elevator equipment where energized equipment and water could create an unsafe condition.
The important distinction is that elevator recall and elevator shunt trip are not the same function. Elevator recall is normally initiated by smoke detection and sends the elevator to a designated or alternate recall level. Elevator shunt trip is an elevator power shutdown function associated with sprinkler protection in specific elevator spaces.
Quick Answer:
Where elevator hoistways, machine rooms, control rooms, or control spaces containing elevator equipment are protected by automatic sprinklers and elevator power shutdown is required, the system must be arranged to disconnect elevator power before sprinkler water creates an unsafe condition. NFPA 72 Section 21.4 provides the fire alarm interface requirements for this elevator power shutdown function.
Elevator shunt trip sequence of operations showing heat detection, fire alarm control, power disconnect, elevator shutdown and sprinkler coordination.
What Is Elevator Shunt Trip?
An elevator shunt trip system automatically opens the elevator's main power disconnect when required by the applicable elevator, building, electrical, and fire alarm codes.
The purpose is not simply to turn off the elevator during a fire. The purpose is to coordinate elevator power shutdown with sprinkler operation so that water is not discharged onto certain energized elevator equipment while the elevator remains capable of movement.
A typical elevator shunt trip sequence may include:
A heat detector or other approved initiating method operates in a sprinkler-protected elevator space.
The fire alarm system processes the elevator shutdown signal.
A listed relay or control interface operates the elevator shunt-trip disconnecting means.
Main operating power to the affected elevator is disconnected.
The disconnecting means remains open until it is manually restored in accordance with elevator and electrical system requirements.
The exact sequence must be coordinated between the fire alarm contractor, electrical contractor, elevator contractor, sprinkler contractor, engineer, and Authority Having Jurisdiction (AHJ).
Elevator Recall vs. Elevator Shunt Trip
Elevator recall and elevator shunt trip work together as part of the overall elevator emergency-control strategy, but they perform completely different functions.
Function
Typical Initiating Device
Primary Purpose
Elevator Recall
Smoke detection or other permitted automatic detection
Moves the elevator to the designated or alternate recall level
Elevator Shunt Trip
Heat detection, pressure/waterflow initiation, or another approved method where applicable
Disconnects elevator operating power before sprinkler discharge creates an unsafe condition
Elevator recall sequence: smoke detection initiates Phase I recall and sends the elevator to the appropriate recall level.
Elevator shunt trip sequence: heat detection or another approved initiating method activates the elevator power shutdown function.
Shunt trip is generally associated with elevators where automatic sprinklers are installed in elevator hoistways, machine rooms, control rooms, control spaces, or similar elevator equipment locations and the application of sprinkler water could create an unsafe operating condition.
The International Building Code requires elevator power shutdown where specified elevator spaces containing elevator equipment are protected by automatic sprinklers. The shutdown arrangement is coordinated through NFPA 72 Section 21.4.
This means you should not determine whether shunt trip is required simply by asking whether the building itself is sprinklered.
Instead, determine:
Whether sprinklers are installed in the applicable elevator space.
Where the sprinkler is located.
Whether elevator equipment could be exposed to sprinkler water.
Whether the elevator is a standard passenger elevator, Fire Service Access Elevator, Occupant Evacuation Elevator, or another elevator type.
Which editions of the building, fire, elevator, electrical, sprinkler, and fire alarm codes have been adopted by the jurisdiction.
2024 IBC Requirements for Elevator Shunt Trip
IBC Section 3005.5 addresses elevator shunt trip.
Where elevator hoistways, machine rooms, control rooms, and control spaces containing elevator control equipment are protected by automatic sprinklers, the IBC requires a means arranged in accordance with NFPA 72 Section 21.4 to automatically disconnect main-line elevator power before the application of water.
The disconnecting means is also required to be non-self-resetting. In other words, power should not automatically restore when the fire alarm initiating condition clears.
Sprinkler activation elsewhere in the building is not intended to indiscriminately shut down elevator power. The shutdown function is associated with sprinkler protection affecting the elevator equipment areas addressed by the applicable code.
NFPA 72 Section 21.4: Elevator Power Shutdown
NFPA 72 Chapter 21 covers emergency control function interfaces. Section 21.4 specifically addresses Elevator Power Shutdown.
Heat Detectors Used for Shunt Trip
When heat detectors are used to initiate elevator power shutdown, they must be selected and arranged so that elevator power is removed before sprinkler operation.
The heat detection must be coordinated with the sprinkler system so that the detector operates sooner than the sprinkler under the conditions anticipated by the design.
NFPA 72 requires heat detection used for this purpose to have a lower temperature rating and greater response sensitivity than the associated sprinkler.
24-Inch Heat Detector Placement
When spot-type heat detectors are used for elevator power shutdown, NFPA 72 requires them to be located within 24 inches of each sprinkler associated with the shutdown function unless an approved engineering method is used to demonstrate that the required operating sequence will occur.
This is why elevator machine rooms and hoistways may have heat detectors positioned immediately adjacent to sprinkler heads rather than laid out using ordinary area heat-detector spacing.
Important: A heat detector used for elevator shunt trip is performing an emergency control function. Do not treat its location as ordinary area heat detection spacing. Its relationship to the sprinkler is critical.
Waterflow or Pressure Switch Initiation
Where an approved pressure switch or waterflow switch is used to initiate elevator power shutdown, NFPA 72 does not permit the use of a time-delay function in that initiating path.
This is very different from ordinary sprinkler waterflow alarm applications where retard or time-delay arrangements are commonly encountered.
Can Elevator Shunt Trip Be Delayed?
Some elevator shutdown designs using heat detection may incorporate a coordinated delay intended to provide additional opportunity for the elevator to complete recall before power is removed.
However, this is not a universal permission to program an arbitrary shunt-trip delay. The sequence must remain coordinated with the elevator safety requirements so that power is removed before sprinkler water creates the hazardous condition the shutdown function is intended to prevent.
Any proposed delay should therefore be reviewed with the elevator contractor, design engineer, and AHJ.
If a pressure or waterflow switch is being used as the elevator shutdown initiating device, the NFPA 72 restriction on time-delay capability still applies.
Shunt Trip Control Circuit Supervision
This requirement is frequently overlooked in both design and installation.
The control circuit used to operate the elevator disconnecting means must be monitored for the presence of the operating voltage needed to perform the shutdown function.
If that operating voltage is lost, the fire alarm system must indicate the required supervisory condition so building personnel know that the elevator shutdown function may no longer be available.
A typical addressable fire alarm installation may use a monitor module and appropriately listed relay or interface arrangement to supervise the availability of the shunt-trip control voltage.
Field Tip: Functional testing should include more than simply tripping the elevator breaker. Verify loss-of-voltage supervision, fire alarm annunciation, relay operation, elevator recall sequence, shutdown sequence, and proper manual restoration.
Smoke Detectors Do Not Normally Initiate Elevator Shunt Trip
One of the most common design mistakes is assuming that the smoke detector used for elevator recall should also operate the shunt-trip breaker.
These are separate functions.
Smoke detection is generally associated with elevator recall.
Heat detection or another approved sprinkler-related initiating method is generally associated with elevator power shutdown.
The final design must follow the adopted elevator, fire alarm, building, sprinkler, and electrical codes for the project.
Fire Service Access Elevators and Occupant Evacuation Elevators
Fire Service Access Elevators and Occupant Evacuation Elevators require special treatment and should not be designed using the ordinary passenger-elevator shunt-trip assumptions.
Under the 2024 IBC:
IBC Section 3007.4 prohibits installing the ordinary elevator shutdown means described by Section 3005.5 on Fire Service Access Elevators.
IBC Section 3008.4 provides the corresponding restriction for Occupant Evacuation Elevators.
The IBC also restricts automatic sprinklers in their associated elevator hoistways and specified elevator equipment spaces.
Always identify the elevator type before designing the fire alarm interfaces.
Elevator Pit Sprinklers and Shunt Trip
Elevator pits create another common area of confusion because the required shutdown arrangement depends on the sprinkler location, elevator configuration, adopted elevator code, and applicable exceptions.
A sprinkler located very low in an elevator pit can be treated differently from a sprinkler located higher in the hoistway because the potential for sprinkler discharge to affect energized elevator equipment is different.
California deserves special attention because elevator installations are regulated by the California Division of Occupational Safety and Health, commonly known as Cal/OSHA, through its Elevator Unit, in addition to the applicable California Building Standards Code.
Older guidance sometimes stated that elevator shunt-trip equipment had to be located outside the elevator machine room. That is not an accurate blanket statement under current California Elevator Unit guidance.
The California Elevator Unit issued a memorandum clarifying the location of shunt-trip equipment.
California permits shunt-trip devices that are incorporated into the design and function of the listed equipment serving as the single main-line disconnecting means to be located in elevator machine rooms, control rooms, and control spaces.
However, shunt-trip equipment that is not incorporated into that listed single disconnecting means is treated differently and is not permitted by that Elevator Unit policy to be located in those elevator equipment spaces.
See the official California Elevator Unit memorandum here:
California projects should also be reviewed against the current edition of the California Building Standards Code and any local amendments adopted by the AHJ.
Where Should the Elevator Shunt Trip Disconnect Be Located?
There is no universal rule stating that every elevator shunt-trip disconnect or breaker must always be located in one particular location.
Location depends on the electrical code, elevator code, equipment listing, elevator configuration, jurisdiction, and whether the shunt-trip components are incorporated into the elevator's listed main-line disconnecting means.
For California installations, follow the California Elevator Unit guidance described above rather than relying on the older assumption that every shunt-trip device must automatically be located outside the machine room.
Resetting an Elevator Shunt Trip Disconnect
Elevator power shutdown is intended to be a non-self-resetting function.
After the initiating condition has been investigated and the fire alarm and elevator systems are ready to be restored, the elevator disconnect must be manually restored using the proper procedure for the specific listed equipment.
Do not assume that resetting the fire alarm control unit should automatically restore elevator power.
Restoration should be performed by qualified personnel in accordance with the elevator equipment manufacturer's instructions, electrical safety requirements, elevator contractor procedures, and AHJ requirements.
Who Is Responsible for the Elevator Shunt Trip Wiring?
Responsibilities vary by project, but the interface normally involves several trades.
Trade
Typical Responsibility
Fire Alarm Contractor
Initiating devices, monitor modules, control modules, relay interfaces, programming, annunciation, and fire alarm testing
Electrical Contractor
Elevator disconnect and shunt-trip power wiring and associated electrical distribution work
Elevator Contractor
Elevator controller interface, recall operation, elevator safety functions, and elevator-side testing
Sprinkler Contractor
Sprinkler locations, temperature ratings, waterflow or pressure interfaces where applicable, and sprinkler system coordination
The construction documents should clearly identify responsibility rather than leaving the trades to determine the interface during final testing.
Typical Elevator Shunt Trip Sequence of Operations
A common sequence for a sprinkler-protected elevator equipment space may look like this:
Smoke detection initiates elevator Phase I recall when required.
The elevator begins traveling toward the applicable recall level.
A heat detector associated with the sprinkler operates.
The fire alarm system initiates the approved elevator power-shutdown sequence.
The shunt-trip disconnect removes the required elevator operating power before sprinkler discharge creates an unsafe condition.
The fire alarm system supervises the availability of the shutdown control circuit.
Elevator power remains disconnected until manually restored by qualified personnel.
This is only a general example. The project-specific sequence must match the elevator type, sprinkler configuration, adopted codes, equipment listings, engineering documents, and AHJ requirements.
Common Elevator Shunt Trip Design Mistakes
Using the elevator recall smoke detector to initiate shunt trip.
Installing the shunt-trip heat detector using ordinary room spacing instead of coordinating it with the sprinkler.
Failing to supervise shunt-trip control voltage.
Using an improper delay on a waterflow or pressure-switch shutdown circuit.
Allowing sprinkler operation elsewhere in the building to shut down elevator power.
Assuming every sprinklered building automatically requires elevator shunt trip.
Failing to distinguish standard elevators from Fire Service Access Elevators or Occupant Evacuation Elevators.
Failing to coordinate sprinkler temperature ratings and heat detector response characteristics.
Failing to coordinate fire alarm, electrical, sprinkler, and elevator contractor responsibilities.
Using outdated California guidance regarding shunt-trip equipment location.
Elevator Shunt Trip Wiring
This article focuses on the code requirements and operating principles behind elevator shunt trip.
For the actual fire alarm control wiring and relay arrangement, see:
Codes and Standards Commonly Used for Elevator Shunt Trip
Elevator power shutdown is a coordinated function involving several different codes and standards rather than a single fire alarm section.
Common references include:
NFPA 72 – Section 21.4, Elevator Power Shutdown
International Building Code – Section 3005.5, Shunt Trip
ASME A17.1/CSA B44 – Safety Code for Elevators and Escalators
NFPA 70 / NEC Article 620 – Elevators and associated disconnecting means
NFPA 13 – Sprinkler protection and sprinkler installation requirements
California Title 24 and California Elevator Safety Orders for California projects
Always verify the exact code editions adopted by the project jurisdiction. A project designed under an older adopted code cycle may not use the same edition referenced by a newly permitted project.
Final Elevator Shunt Trip Checklist
Before approving an elevator shunt-trip design, confirm:
☐ Is sprinkler protection installed in the applicable elevator space?
☐ Is elevator power shutdown actually required for that location?
☐ Is the elevator type clearly identified?
☐ Are recall and shunt trip being treated as separate functions?
☐ Is heat detection properly coordinated with each applicable sprinkler?
☐ Are heat detector temperature and response characteristics coordinated with the sprinkler?
☐ Is the shutdown control circuit supervised for operating voltage?
☐ Are prohibited time delays avoided?
☐ Is the disconnecting means non-self-resetting?
☐ Have the fire alarm, electrical, elevator, and sprinkler contractors coordinated responsibilities?
☐ Have the applicable adopted codes and local amendments been confirmed?
More Elevator Fire Alarm Resources
Continue learning with these Fire Alarms Online resources:
Important: Fire alarm, elevator, sprinkler, building, and electrical requirements vary by adopted code edition and jurisdiction. Always verify the applicable project documents, equipment listings, local amendments, elevator authority requirements, and AHJ interpretation before construction or modification.
Depending on your fire alarm installation, you may need to install a magnetic door holder at the location of each fire door. A magnetic door holder is a relatively simple device that when powered, typically by 24VDC or 120VAC, will create a magnetic pull. The magnetic portion of this device is installed on the wall that meets the open fire door. Now to tie this whole concept together, you will need to install the necessary hardware on the fire door itself. It is very important that you line the door hardware up with the magnetic door holder as close as possible. If the two do not meet precisely, you may not acquire the necessary contact to hold open a heavy fire door with the extra tension caused by the closure mechanism.
Now with all of that said, you need to make sure that the magnetic door holder is mounted securely within the wall. Be sure to not use cut in boxes, screw in type anchors or even toggle bolts. This device needs to be mounted to the structure. The best way to go about this is quite simple.
Step #1 Open the fire door all the way against the wall where the magnetic door holder is to be mounted. With this done, mark the wall lightly where you will need to roughly install the door holder. Door holders are typically installed towards the upper/outer edge of the fire door.
Step #2
Use a stud finder to locate a stud near your mark. Make sure to use the stud that will give you sufficient room to mount your box and still stay within the necessary area of the fire door. Cut out a section of drywall that runs between two studs. Make sure the hole is also tall enough to mount a 4S electrical box with brackets.
Step #3
Take some steel stud and cut a piece that matches the width between the two studs. Now mount your 4S electrical box to a stud of the existing frame via the brackets. This will secure one side of the box. Use the piece of steel stud you cut and place it behind your box and between the two studs. This will give your box the support it requires. Make sure to fasten the box to your steel stud and then fasten the steel stud at both ends to the existing building studs.
Step #4
Install a single gang mud ring (depth depends on your drywall application). Once installed, replace the drywall around magnetic door holder back box. Once the drywall is finished install your magnetic door holder and power it up.
Step #5
With power on the fire alarm door holder, stick the door hardware to the magnetic portion of the device and open the fire door until they meet. Here we are using the power of the door holder to hold the door hardware while we mark the fire door with the mounting holes. Most door holders come with a simple to use sticker for purposes of marking the fire door.
Step #6
Now for the magnetic door holder pictured here, we drilled two 1/8" pilot holes then followed them up with 5/8" holes. Once we completed the drilling, we screwed the door holder hardware tightly to provided bracket on the back side of the fire door.
Below is a picture of what happens to a magnetic door holder after repeated use if it is not mounted to the structure properly.
It is always fun to compare your work to others. Especially when you have a habit of doing things to current codes and applicable standards. Today we came across a problem seen all to often on constructions sites both old and new.
Fire Caulk.
It always seems that contractors become very lazy at this stage of the installation. 9 out of 10 times it appears that the installer just slaps some fire caulk around a penetration and calls it a day. Not realizing how important the fire caulk stage is, most people just leave it.
To install fire caulk the correct way, follow these simple steps:
1. Cut a piece of EMT conduit long enough to penetrate the entire wall (both sides) and have the pipe stick out approximately 6 inches on each side.
2. Pull your wires trough the EMT and then place the EMT through a hole in the fire rated wall.
3. Use mineral wool to pack the ends of the EMT. Make sure to wrap the mineral wool around the wires and center the wires within the EMT as much as possible. Now shove the mineral wool inside the conduit.
4. Fire caulk the ends of the EMT (over the mineral wool) 1" deep and have the fire caulk stick out of the conduit approximately 1/2" to 3/4".
5. Now use the fire caulk around the EMT and the actual fire rated wall. Make sure to get the fire caulk in 1" and at least 3/4" all around.
6. Make sure to do this on both sides.
You may have seen your local hardware store trying to push you on Carbon Monoxide detectors stating its the law. Read below to know for yourself!
The new requirements in the 2012 edition of the International Fire Code (IFC) and the International Building Code (IBC) require the installation of CO detection in new and existing Group-R and Group-I occupancies, such as hotels, dormitories, apartment buildings, hospitals and nursing homes.
Section 908.7 of the 2012 IFC and IBC requires CO detection to be installed in “newly” constructed Group-R and Group-I occupancies if the building contains a fuel-burning appliance or an attached garage. Also CO alarms shall be installed and maintained in accordance with NFPA 720, Standard for the Installation of Carbon Monoxide (CO) Detection and Warning Equipment, and the manufacturer’s instructions.
Section 1103.9 of the IFC covers the requirements for existing Group-R and Group-I occupancies, these requirements are the same as those in 908.7 for newly constructed occupancies.
If sleeping units or dwelling units do not contain a fuel-burning appliance or have an attached garage, however are located within a building with a fuel burning appliance or an attached garage, CO detection is not required if any of the following conditions are present:
• The sleeping unit or dwelling unit is located more than one story above or below any story that contains a fuel-burning appliance or an attached garage
• The sleeping unit or dwelling unit is not connected by duct work or ventilation shafts to an attached garage or any room containing a fuel-burning appliance
• The building is provided with a common area CO alarm system. Also, Section 908.7.1 of the 2012 IBC and IFC clearly permits system connected CO detectors to be installed as a primary form of protection if they are installed and maintained in accordance with NFPA 720 and listed as complying
with ANSI/UL 2075.
Designers and plan reviewers ask this constantly:
“Are you required to install a heat detector in the bottom of the elevator shaft (the elevator pit)?”
The short answer is: sometimes, and only when specific code-driven conditions exist.
This topic sits at the intersection of multiple standards. For most U.S. jurisdictions using the latest model codes, the governing framework is:
2024 IBC (Chapter 30: Elevators and Conveying Systems)
2024 IFC (elevator-related fire code provisions and operational coordination)
NFPA 72 (2022) Chapter 21 (Elevator Recall and Elevator Power Shutdown)
NFPA 13 (2019/2022 as adopted) hoistway/pit sprinkler rules and exemptions
ASME A17.1 / CSA B44 (Safety Code for Elevators and Escalators) Firefighter’s Emergency Operation and sprinkler-related provisions
Important: The fire alarm heat detector is only tied to elevator shutdown when a sprinkler is present and shutdown is required.
A pit heat detector is not a universal requirement.
A sprinkler head in an elevator pit is typically intended to control a fire caused by accumulated debris (trash, packaging, lint, etc.)
that can fall through door gaps over time. Whether that sprinkler is required (or exempt) is primarily a sprinkler-code question
governed by NFPA 13 and referenced by the adopted building/fire code.
1) First Condition: Is There a Sprinkler in the Pit?
Under NFPA 13 (2019/2022 as adopted), sprinklers in hoistways and pits are required unless the installation meets specific exemption criteria.
In modern designs, exemptions are common depending on construction type, elevator type, and whether combustibles are present.
Code References:
NFPA 13 (2019/2022 as adopted): Hoistway and pit sprinkler criteria and exemptions (section numbering varies by edition).
2024 IBC / 2024 IFC: reference adopted sprinkler standards for system design and installation.
If there is no sprinkler in the pit, then there is generally no pit heat detector requirement for elevator power shutdown,
because there is no sprinkler discharge to coordinate with.
2) Second Condition: Sprinkler Elevation Above Pit Floor (The 24-Inch Rule)
If a sprinkler exists in the pit, the next key question is:
Is the sprinkler located within 24 inches (2 feet) of the pit floor?
Under ASME A17.1 / CSA B44, sprinklers installed in certain elevator locations can trigger special arrangements
related to elevator power shutdown. However, when a sprinkler is installed very low (within 24 inches of the pit floor),
shutdown coordination is often not required because energized elevator equipment is not typically located in that zone.
Code References:
ASME A17.1 / CSA B44: Provisions addressing sprinkler interactions and elevator emergency operations (edition and section numbering vary by adoption).
2024 IBC Chapter 30: Elevators governed by ASME A17.1 (referenced standard) and emergency operation requirements.
3) NFPA 72 (2022): When a Pit Heat Detector Is Required for Shutdown
Elevator power shutdown (often called “shunt trip”) is governed by NFPA 72 (2022) Section 21.4.
When shutdown is required to occur prior to sprinkler discharge, NFPA 72 establishes the rules for the initiating means.
NFPA 72 (2022) 21.4.1 – Elevator power shutdown intent and coordination (power removed prior to sprinkler discharge where required)
NFPA 72 (2022) 21.4.2 – Heat detection used for shutdown initiation installed within 24 inches of each sprinkler head
NFPA 72 (2022) 21.4.3 – If waterflow/pressure switches are used for shutdown initiation, time delay is not permitted
Key distinction: Smoke detectors are used for elevator recall under NFPA 72 (2022) Section 21.3.
Heat detection (or an approved equivalent initiating means) is used for elevator power shutdown under Section 21.4.
Industry practice: Use heat for shutdown, smoke for recall. Mixing these functions is a common plan-review failure.
4) Mini Sequence of Operations (SOO): Elevator Pit Shutdown Only
Below is a compact, plan-review-friendly SOO focused only on pit shutdown coordination.
Adapt point names to your panel programming standards.
Input
Device / Condition
FA System Action
Output / Result
Notes
HD-PIT
Pit Heat Detector (within 24" of pit sprinkler where shutdown is required)
Alarm; initiate elevator power shutdown sequence
OUT-SHUNT (shunt trip control to disconnect/breaker)
NFPA 72 (2022) 21.4.2 proximity; coordinate rating vs sprinkler temperature
LHD-PIT (optional)
Linear Heat Detection Cable (listed, where used/approved)
Alarm; initiate elevator power shutdown sequence
OUT-SHUNT
Allowed as listed initiating means when installed/tested per manufacturer and accepted by AHJ
WF-PIT (optional)
Waterflow / Pressure Switch (dedicated elevator branch where used)
Alarm; initiate immediate shutdown
OUT-SHUNT
No time delay permitted per NFPA 72 (2022) 21.4.3
TRB-PIT
Device / Module Trouble (open, ground, loss of supervision)
Trouble only (no shutdown)
None
Document supervision and response policy in record drawings
5) Three Common Shutdown Methods (Modern Practice)
#1 – Waterflow / Pressure Switch Method
This method uses a waterflow/pressure switch on the elevator sprinkler branch to initiate shutdown.
If used, ensure compliance with NFPA 72 (2022) 21.4.3, including the “no delay” requirement.
#2 – Fixed Temperature Heat Detector (Most Common)
A heat detector is installed within 24 inches of the sprinkler head used for shutdown initiation (NFPA 72 (2022) 21.4.2).
It must be selected/arranged to activate before sprinkler discharge temperature.
#3 – Pre-Action System with Supplemental Detection
Pre-Action systems can be used in certain elevator spaces. Supplemental detection (typically heat) releases the pre-action valve.
The same initiating condition can also be used to trigger elevator shutdown where required, with AHJ/elevator coordination.
6) Compliance Comparison: 2016 vs 2022 vs 2024 Framework
Topic
NFPA 72 (2016 Era)
NFPA 72 (2022)
2024 IBC / 2024 IFC
Elevator Shutdown Rules
Chapter 21.4 structure used widely (older projects often cite 21.4.x)
Chapter 21.4 remains, with clearer coordination expectations and modern adoption
Model codes reference NFPA 72 for interface and NFPA 13 for sprinklers
Heat vs Smoke Function
Frequently mixed up in design
Clear separation: recall (21.3) vs shutdown (21.4)
Adopts NFPA 72 concepts through referenced standards
24" Proximity Requirement
Commonly cited as 2 ft from sprinkler for shutdown detection
Still required for shutdown initiation (21.4.2)
Drives coordination when sprinklers exist under NFPA 13 and ASME A17.1
Waterflow Method Timing
No time delay permitted
No time delay permitted (21.4.3)
Enforced via NFPA 72 referenced requirements
Final Code-Based Answer
A heat detector in the elevator pit is required only when:
A sprinkler head is installed in the pit (NFPA 13 as adopted), and
The sprinkler is located above the “low zone” where ASME A17.1 would not exempt shutdown coordination (commonly referenced as within 24 inches of the pit floor), and
Elevator power shutdown prior to sprinkler discharge is required (NFPA 72 (2022) 21.4).
If there is no pit sprinkler, a pit heat detector for shunt trip is generally not required.
If the pit sprinkler is within 24 inches of the pit floor, shutdown coordination may not be required per ASME A17.1 practice.
Always verify local adoption, amendments, and AHJ interpretation.
Interface wiring responsibilities (typical):FA Vendor furnishes/terminates FA monitor/control modules and provides dry-contact outputs/inputs;
Electrical Contractor installs/terminates shunt-trip disconnect/breaker control wiring;
Elevator Contractor terminates at the elevator controller and validates recall/shutdown operation during testing with the AHJ.
Notifier offers a great arrangement of fire alarm and life safety products. Be sure to check out this
video courtesy of www.notifier.com. At www.notifier.com you will also be able to locate cutsheets, data sheets, calculations, specifications and other documentation for their product line.
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Sometimes in our industry, there is a need to convert volts AC (alternating current) to volts DC (direct current).
You may run into this scenario when using a CCTV power supply with an AC (alternating current) output but yet you have DC (direct current) cameras. Instead of replacing the power supply you can make a diode rectifier.
Please note that you can purchase these pre-made from stores like ADI or Frys.
A diode rectifier is a simple contraption made up of 4 diodes placed in a specific order. This will allow you to connect an AC source on one end yet get a DC source out of the opposite. In the picture below you will see how to place the diodes in order to achieve this.
Another simple way to think of it is the transformer that comes with your typical fire alarm control panel is rectified. You connect 120 volts AC (alternating current) to the input and get 24 volts DC (direct current) out of the output. The transformer is stepping the voltage down from 120 to 24 and the rectifier is converting the AC voltage to DC voltage.
Pretty slick right?
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What does it mean to pre-wire for future ADA adaptability?
The 2021 International Fire Code or IFC is where we look to find out what fire alarm requirements to follow when designing systems. Specifically Chapter 9 "Fire Protection Systems". If we dive deeper into section 907, we are informed as to what is required for each occupancy group.
For this article, we will be reviewing the requirements for an "R-2" occupancy. As defined in the International Building Code or IBC, an R-2 group occupancy consists of: "occupancies containing sleeping units or more than 2 dwelling units where the occupants are primarily permanent in nature, including: Apartments Houses, Boarding House with more than 16 occupants, Convents, Dormitories, Fraternities and Sororities, Hotels (non-transient), Live/Work units, Monitories, Motels (non-transient), Vacation timeshare properties."
Since this article revolves around the requirements to pre-wire for future visual alarms, we will stay away from discussing the initiating side of the code. Full requirements for an R-2 occupancy.
International Fire Code Section 907.5.2.3.3 Pre-Wire for Group R-2
Section 907.5.2.3.3 states "In group R-2 occupancies required by section 907 to have a fire alarm systems, all dwelling units and sleeping units shall be provided with the capability to support visible alarm notification appliances in accordance with Chapter 10 of ICC A117.1. Such capability shall be permitted to include the potential for future interconnection of the building fire alarm systems with the unit smoke alarms, replacement of audible appliances with combination audible/visible appliances. or future extension of the existing wiring from the unit smoke alarm locations to required locations for visible appliances."
This is a major upgrade in comparison to a group R-1 occupancy such as Hotels and Motels. In these facilities, the code gives us parameters as to how many rooms with visible alarms are needed based on the total quantity of sleeping units.
"So what does all this mean?"
In basic terms all living spaces within a group R-2 occupancy must contain the necessary wires, raceways and boxes to support the ability to upgrade to audible and visual notification throughout. ADA aside, our design must provide at least 75 dB in all areas of the quest room. On top of this, your jurisdiction may now be requiring the fire alarm occupant notification to produce a 520Hz low frequency tone in all sleeping areas. Find out more about 520Hz requirements.
A lot of fire alarm designers are confused to the actual requirements of this code section. To be clear, it is the intent of the code to have a fully functional low frequency audible occupant notification system that can be upgraded with visual alarms without cutting walls, adding boxes or running new conduit. All of the necessary wire or a conduit raceway must be in place to all living spaces, sleeping rooms and bathrooms within each living space. As stated in the paragraph above, we need a minimum of 75 dB throughout the space. To achieve this, it's typical to have a low frequency audible appliance in each sleeping room as well as the living space. This design makes it easy to just swap out the low frequency sounder appliance for a combination low frequency and visual appliance. Don't forget that you will need a box and wire to each restroom within the guestroom.
ADA section 4.28 "Alarms" gives us the requirements for visual appliances within ADA compliant areas. Pay close attention to section 4.28.4 "Auxiliary Alarms" Units and sleeping accommodations shall have visual alarms connected to the building emergency alarm system or shall have a standard 110-volt electrical receptacle into which such an alarm can be connected and a means by which a signal from the building emergency alarm system can trigger such an auxiliary alarm. When visual alarms are in place the signal shall be visible in all areas of the unit or room. Once a group R-2 living unit is upgraded to meet ADA requirements for visual alarms, you will need a low frequency audible tone of at least 75 dB throughout as well as visual alarms in all areas of the living unit. This includes restrooms.
Side note: NFPA 72 2022 Table 18.5.5.10.3 informs us of the candela rating required visual appliances installed in sleeping areas.
Distance from the ceiling to the top of the visual appliance lens:
> or = to 24 inches = 110 Candela
< 24 inches = 177 Candela
This standard was put in place as smoke migrates to the ceiling in the event of a fire. It is common sense that a more intense strobe flash would be required to shine thorough the thicker smoke found closer to the ceiling and still have the ability to awake a sleeping occupant. This is why we are required to install a 177 candela strobe when located less than 24" from the ceiling.
Best installation method to accomplish ADA adaptability for Group R-2 occupancies.
Run a trunk run down the corridor with Notification Appliance Circuit (NAC) loops as well as a Signaling Line Circuit (SLC) pulled into a J-Box within the closet of each living unit. It is best to pick the closet that contains the unit's breaker panel. From this J-Box pull your notification circuit loop through all appliance locations. In the event the room needed to become adaptable, simply splice your incoming/outgoing NAC loop through in the J-Box. This way the notification field wiring loop within the living unit is separate from the rest of the existing building NAC circuits. Install a single output remote power supply listed for fire within the closet and power up with a dedicated 120 AC circuit. Use the SLC in the closet to install an addressable smoke detector and control module to protect and activate the power supply. See the example layout below:
Now keep in mind that these audible / visual notification appliances will need to activate via general alarm, floor alarm or an alarm from within the unit itself. To activate the notification appliances from within the living unit, you could either install addressable system smoke detectors or connect addressable mini modules to the 120 VAC UBC smoke alarms. The detectors or modules would activate the control module connected to the power supply as well as indicate a supervisory condition on the fire alarm control unit (FACU).
"Effective January 1st 2014, audible appliances provided for the sleeping areas to awaken occupants shall provide a low frequency alarm signal that complies with the following: (1) The alarm signal shall be square wave or provide equivalent awakening ability. (2) The wave shall have a fundamental frequency of 520 Hz +/- 10 percent."
We got a glimpse of the future requirement in the 2010 Version of NFPA 72 section 18.4.5.3 page 102. Here we could see that come January 1st 2014, there would be a requirement for fire alarm designers to use a 520Hz square wave low frequency sounder within all sleeping areas. There have been multiple studies performed that validate the belief that a 520 Hz low frequency audible tone will have a greater chance at awakening a sleeping occupant. The lower frequency also has greater chances of awakening people whom are intoxicated or hard of hearing.
Lets fast forward to the 2016 edition of the standard. NFPA 72 version 2016 notes the same requirement in section 18.4.5.3 page 112.
Now, here we are in the year 2016 and yet not everyone is following this standard. You may ask yourselves why is our AHJ or authority having jurisdiction not requiring our fire alarm installation company to install the new 520Hz low frequency sounders for sleeping areas. Keep in mind that the particular state you install fire alarms in may have an older code adopted. Click to learn the difference between fire alarm codes and standards.
How do you know if your state or region is requiring 520Hz low frequency sounders?
The International Fire Code or IFC 2018 edition chapter 80 as well as the International Building Code or IBC 2018 edition chapter 35 both reference NFPA 72 2019. With this said, you will need to find out if your jurisdiction has adopted the 2012 or newer version of the IBC or IFC code. Better yet, System Sensor has provided a detailed map of the States and Regions currently adopting this code. See below:
Fire fighters are there to help you. When a fire breaks out they are rushing out to the fire to stop it before it can cause too much damage. Help them out by getting a dry riser. The dry riser is something that can be fitted into your building to help fight fires as soon as they break out. The outlet that exists outside the building can aid fire fighters further by making sure that they have a source of water they can use.
Dry Sprinkler Pipe System - How It All Works
The dry riser works on the principle of compressed air. Compressed air is what differentiates it from the dry riser’s counterpart; the wet riser, which utilises water-filled pipes. The compressed air works by pressing the valve shut that prevents the water from entering the pipe. Once the air is released the valve opens up and the water can shoot through the pipes.
At the end of the pipe is a sprinkler system. Sprinklers open up when a fire has been detected. Naturally, once the sprinkler opens the compressed air disappears and the water can then attack the flames. They may not necessarily be able to eliminate the fire, but what they can do is to make sure that it’s limited. Think of it as giving fire fighters some additional time to get to the scene of the incident.
Dry Pipe Sprinkler Systems - Help Your Local Fire Fighters!
Your local fire fighters are not always going to be in the best position when confronted with a fire. Due to rapid urbanisation, it’s now harder than ever to find a suitable water outlet that can provide the supply that’s needed to combat the most serious fires. Dry risers have to get their water from somewhere, and that comes in the form of an inlet valve. Fire fighters are able to attach their tools to this valve and draft the water from there.
So you don’t have one of those things and they are forced to look elsewhere. Those extra minutes spent looking for a suitable supply of water could mean the difference between your property burning down and the structure being saved. Surely the desired outcome is going to be obvious here?
If you suspect the valve in your high rise has been tampered with ring the dryriser theft hotline.
Dry Pipe Sprinkler System - Where are they Fitted?
From a glance, it seems as if the dry riser system is quite vulnerable. Once the fire takes hold it can attack the pipes and cut off the supply. This is not the case at all. All of these systems are required by law to have their main pipes in a place that’s resistant to fire. Escape stairways are the number one places where these can be found. Note, these fire-resistant areas are not necessarily going to protect it forever. On the contrary, sooner or later the fire will burn through.
Primarily, it’s to combat minor fires before they spread. If a major fire breaks out, or even worse an explosion, then nothing can be done until the fire fighters arrive.
Dry Pipe Sprinkler System - How Expensive Are They?
If you are looking to install one of these systems then one of the things you will be looking at is the price. Of course, the price is very important because nobody wants to invest a great deal of money in anything. Small businesses may also have trouble meeting large costs, so affordability is perhaps the most important factor. The good news is that companies are offering these systems at a cost-effective price. Regular deals are constantly being employed to encourage people to invest in these systems.
Before you read on please be advised that this tactic is only to be used in training FACU / FACP applications. It is not the intention of Fire Alarms Online to provide this information to eliminate the need for battery backup on a FACU Fire Alarm Control unit, MNS Mass Notification System, RPS Remote Power Supply, etc.
FACP is Normal without Batteries WOW!
There is a way to connect an FACU Fire Alarm Control Unit without backup batteries and have it remain in the normal condition. Now like I mentioned above, this is typically only used if you have a training and or demonstration FACU that you travel with. You can also use this trick if you have a redundant FACU in your shop used for training (only if the system is not an approved life safety system for the site).
The backup battery charger on an FACP, FACU, MNS, RPS, etc. is always looking for 24VDC. This is how it supervises the backup batteries. In other words, this is how the fire alarm control unit knows that backup batteries are present. The same terminals on the charger, also put out 24VDC in order to constantly charge the backup batteries so that they are always ready in the event of primary power loss.
FACU Backup Battery Requirements
Most jurisdictions require 24 hours of standby and 5 minutes of alarm for a horn/strobe system and 24 hours of standby and 15 minutes of alarm for a voice system. See here for battery backup calculations.
With the use of one simple diode, you can accomplish this feat. Simply place the Anode (+ Solid Black) side of the diode into the non-resetable positive 24VDC power output on the FACU / FACP. Now place the Cathode (- Stripe) side of the diode into the positive terminal of the backup battery charger.
How this works: Think of a diode as a one way gate. Electrical current can flow through it in only one direction. So this trick is actually quite simple. The diode is providing a positive current path from the +24VDC output on the panel FACU / FACP and into the + terminal of the battery charger thus tricking it into believing there are backup batteries in place. The reason for the diode is very important. You need to remember that the battery charger puts out 24VDC as well. With that said, we need to block that power from coming back into the +24VDC output on the FACP / FACU. Here is a picture to help explain this trick on how to keep an FACP / FACU in the normal condition without backup batteries.
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All electrical conductors include a small amount of resistance. This resistance increases if the length of the conductor increases or or the conductor size decreases. Think of blowing air through a hose. If the hose diameter decreases and or the length increases it would be harder to blow through. You can also think of freeway traffic as resistance. The freeway is the conductor. The wider the freeway, the faster and smoother you travel.
As electrical current flows through the conductor it will experience a decrease in voltage between the source (starting point) and at various points along the conductor path. Another example to look at is the voltage drop in a 1000 foot run of 16 AWG wire would be greater than that of a 1000 foot run of 12 AWG. This is simply because a 16 AWG conductor is smaller in diameter than a 12 AWG conductor.
Fire alarm equipment LISTED to the standards of the National Fire Protection Association and Underwriters Laboratories (U.L.) is tested to determine if can operate properly at 85% of the rated nameplate voltage. This limit was set in place to make sure the circuit can deal with a "brownout" condition or a possible voltage drop which might result from excessive resistance in the system wiring.
As required in the CFC (California Fire Code), fire alarm designers are required to prepare voltage drop calculations for the notification appliance circuits (NAC) as part of the design. These voltage drop calculations must be included in the submittal plans and specifications. This is to assure that the devices on the system are supplied with electrical power within the operating voltage range.
You as a designer can use several different methods to calculate voltage drop on a fire alarm circuit. One method calculates the actual voltage drop for each length of cable and device within the circuit and the other calculates the overall voltage drop. Either method will have slightly different results but should be acceptable by your local AHJ (authority having jurisdiction)
The suggested maximum allowable voltage drop on a fire alarm circuit is 10% or the voltage drop included in the fire alarm control panel installation guide, whichever is less.
"Lump Sum Method"
Step #1) Take the total current of the circuit. You can achieve this figure by adding up the current draw of each device on the circuit. This will represent "A"
Step #2) Measure out the length of the circuit in feet. Do not double the distance of the circuit for 2 wire loops unless you want to use a multiplying factor of 10.8 versus 21.6 (see step #3). This will represent "L"
Step #3) Use a multiplying factor of 21.6. This number represents the resistivity of copper conductors. This is a constant used in the formula.
Step #4) Find the Circular Mils for the particular gauge wire you are using. This can be found in the National Electrical Code (NEC) chapter 9 table 8. #14 AWG is 4110 and #12 AWG is 6530. This will represent "C.M".
A x L x 21.6
------------- = VD
C.M.
Example .356 x 450' x 21.6
------------------- = 0.530 Volts Dropped
6530
To find the percentage of voltage dropped do the following:
0.530 / 24 = 0.022
0.022 x 100 = 2.2
= 2.2% Voltage Drop
Now remember you can also perform this calculation for each individual length of wire and device on the circuit. This is known as the "point-to-point" method. This is a better way to perform the calculation as it gives you a chance to really break down the circuit and pin point exactly where a circuit must end do to voltage drop. Simply use the above formula for each wire run and add the voltage drop totals for each circuit section together for the total voltage drop. Then divide by the source voltage (in this example we will use 24VDC) and then multiply by 100 to come to a total voltage drop percentage.
I will be adding info in the near future on the calculations for the "point-to-point" method using Ohm's Law
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