1. Lecture 3: FDAS Dr. Lory Liza D. Bulay-og SYSTEM DESIGN
Professional Electronic Engineer
Associate Prof, USTP, CDOC Philippines
Former Research Fellow , University of Surrey, England

2. SCOPE
Fire Alarm Plan shall depict the following major details:
Location of Central Fire Alarm Control Panel, MIMIC / HMI display.
Location of Local Fire Alarm Panel.
Location of Smoke Detectors, Heat Detectors (including below false floor & above false ceiling), Linear Beam Detectors, Manual call points inside every building.
Location of Horn, Strobe inside every building.
Location of Manual Call Points and Horn, Strobe, Siren in plant and Utility areas.
Location of Linear Heat Sensing Cable.
Cable type details and routing in each building, plant & utility areas.
Location of Junction boxes.

3. SCOPE
Loop diagram for each loop.
Typical installation details of detectors, manual call points, horn, strobe, linear heat sensing cable, junction box etc.
Relevant Notes & Legends shall be included.
Note:
In case, Clean Agent System Panel is combined with local Fire Alarm Panel as per ITB / project requirement, all clean agent system panel devices e.g. pre-discharge lamp, discharge lamp, manual release station, abort switch, solenoid valve etc. shall also be shown in Fire Alarm Plan.

4. INSTRUCTIONS
1 Requirement for preparing Fire Alarm Plan
Fire Alarm Plan shall be prepared based on latest Plot Plan drawings only.
Fire Alarm Plan for buildings shall be as per latest Civil / Architectural drawings.
HVAC air change data required to calculate indoor detectors quantity.
Fire Fighting Block Diagram
Fire & Gas Block Diagram
Fire Alarm Detection System calculation based on NFPA/ local regulation.
2 Key Activities
Detectors and MCPs shall be located based on guidelines of NFPA / Local regulation requirement.
Block Diagram for Fire Alarm System shall be prepared based on Fire Fighting Block Diagram / Fire & Gas Block Diagram / Fire Alarm Calculation / NFPA / Local regulation / ITB requirement.

5. Fire Alarm Plan shall be prepared in co-ordination / interface with other systems such as
F&G (Instrumentation)
HVAC (Piping)
Fire Fighting e.g. Clean Agent System (Piping)
PAGA (Electrical)
Lighting (Electrical)
d) Fire Alarm detector shall be located keeping in view the spacing between detectors/ clearance from wall & HVAC duct etc.
Fire Alarm cable route for outdoor shall follow Electrical/ Instrument cable routes as far as possible or as specified in ITB.
Connection of Fire Alarm devices shall be as per Star / Ring topology and necessary JBs etc. shall be properly located.
Field equipment to be installed in classified hazardous area shall have appropriate ’Ex’ protection as per Hazardous Area Classification.

6. The fire detection system in process, storage and utilities area consists of the following:
Alarm Push Buttons (Manual Call Points / Break Glass Units)
Linear Heat Sensing Cable for Floating Roof (where ever applicable as per ITB).
i) Fire Alarm in the Plant consists of visual alarm (red flashing light) and audible alarm located near Alarm Push Buttons.
j) Fire detection system in the buildings consists of the following:
Smoke Detectors.
Heat Detectors.
Alarm Push Buttons (Manual Call Points / Break Glass Units).
Heat Sensitive Cable.
Linear Beam Detectors.
k) Fire Alarm Plan in the buildings shall cover optical/ acoustical alarm (horn / beacon) located outside the building near the main entrance and inside the building in the corridor/ main entrance or in appropriate location as per relevant standard.

7. INSTALLATION DETAILS
The FACP or network display shall be located in the fire command center of the building or complex. In the absence of fire command center, it should be located ideally in a position clearly visible from the main entrance lobby.
The FACP, the network display and all panels of the network shall be located in a position where the temperature shall not exceed 30°C.
The FACP shall be secured with lock and key to allow only authorized personnel to access and operate it.

8. INSTALLATION DETAILS NFPA-72 (2013) Clause Explanation
5 ft (1.5 m)
Manual Fire Alarm Boxes (Stations)
Alarm Notification Devices
NFPA-72
(2013) Clause
Explanation
Manually actuated alarm-initiating devices for initiating signals other than for fire alarm shall be permitted if the devices are differentiated from manual for fire alarm boxes by a color other than red and labeling.
The operable part of a manually actuated alarm initiating device shall be not less than 42 in. (1.07 m) and not more than 48 in. (1.22 m) from the finished floor.
Manually actuated alarm-initiating devices shall be permitted to be single action or double action.

9. NFPA-72 (2013) Clause Explanation Manual Fire Alarm Boxes (Stations)
Manual fire alarm boxes shall be used only for fire alarm initiating purposes.
Manual fire alarm boxes shall be installed so that they are conspicuous, unobstructed, and accessible.
Unless installed in an environment that precludes the use of red paint or red plastic, manual fire alarm boxes shall be red in color.
Manual fire alarm boxes shall be located within 5 ft (1.5 m) of each exit doorway on each floor.
Additional manual fire alarm boxes shall be provided so that the travel distance to the nearest manual fire alarm box will not exceed 200 ft (61 m), measured horizontally on the same floor.
Manual fire alarm boxes shall be mounted on both sides of grouped openings over 40 ft (12.2
m) in width, and within 5 ft (1.5 m) of each side of the grouped opening.

10. NFPA-72 (2013) Clause Explanation 17.4.7
Installation Details (Initiating Devices)
NFPA-72
(2013) Clause
Explanation
17.4.7
Where smoke detectors are installed in concealed locations more than 10 ft (3.0 m) above the finished floor or in arrangements where the detector’s alarm or supervisory indicator is not visible to responding personnel, the detectors shall be provided with remote alarm or supervisory indication in a location acceptable to the authority having jurisdiction.
17.4.8
If a remote alarm indicator is provided for an automatic fire detector in a concealed location, the location of the detector and the area protected by the detector shall be prominently indicated at the remote alarm indicator by a permanently attached placard or by other approved means.
17.4.9
Where required by and unless the specific detector alarm or supervisory signal is indicated at the control unit (and on the drawings with its specific location and functions), remote alarm or supervisory indicators shall be installed in an accessible location and shall be clearly labeled to indicate both their function and any device or equipment associated with each detector.

11. Installation Details (Initiating Devices)
For areas where people are sleeping, sounder devices should produce a minimum 75dB(A) at the bed-head with all doors shut. In buildings likely to provide sleeping accommodation for the hearing impaired, consideration should be given to the incorporation of both audio and visual devices.

12. FIRE ALARMS
Voltage Drop Calculations

13. Fire Alarms - Voltage Drop Calculations
Table of Contents
Page
- Subject 3
The Code Requirement & Qualifier 4
The Purpose of Voltage Drop Calculations 5
Calculation Considerations 6
Fire Alarm & NAC Panels 8
The End-of-Line (EOL) Voltage Drop Calculation 9
NAC Voltage Drop Calculation Example
The EOL Voltage Drop Calculation Formula
The Point-to-Point Voltage Drop Calculation Formula
Regulated of FWR?
Info Needed with Any Voltage Drop Calculation Submittal
Estimating Wire Lengths for Voltage Drop Calculations
1313

14. The Code Requirement:
NFPA72, 2002 Edition, excerpt from , “…At the authority having jurisdiction’s request, complete information regarding the system or system alterations, including specifications, shop drawings, battery calculations, and notification appliance circuit voltage drop calculations shall be submitted for approval.”
Qualifier: Most listed fire alarm systems sold in the USA are 24 volt systems. A few (mostly combination burg/fire panels) operate on 12 volts. For the purpose of this course, all discussion and examples presented assume that the control panels are 24 volt systems. In any event, the same theories and math apply to 12 volt systems too, though the panel cut-off voltage will be half that of 24 volt systems.

15. The Purpose of Voltage Drop Calculations
To confirm system will function in a worst case situation.
At end of secondary power standby period.
With all notification appliance circuit (NAC) zones in alarm.
Submitting voltage drop calcs meets NFPA 72 minimum installation requirements for AHJ submittals.
– It’s important that those calcs are based on reality to ensure the system will work.
Reasons why accuracy is important:
– Confirms notification circuits will work at all times (if installed right).
Confirms quantity of power
supplies needed Supports
equipment wall space planning
Supports 120 VAC primary supply Circuit coordination planning
Supports development of future circuit design changes (like tenant improvements) where practical
Additional voltage drop calculations for auxiliary power supply output circuits (like power for beam or flame detectors) makes good sense to ensure the design will work as planned.
Not required, but should be someday. 4That’s another story for another day.

16. Calculation Considerations
There are several ways (methods) to perform voltage drop calculations:
End-of-line (EOL), point-to-point (PTP), load-centering.
Load centering isn’t often used, though conservative.
EOL method is most simple, most conservative, and thus least accurate.
Fewer math steps makes it easy to do by hand with a calculator.
Results can provide lots of “head room” for future.
PTP method is also always somewhat conservative; has much more math involved; and, provides more accurate results.
Generally used with a spreadsheet program because of the many math steps.
Is often used in calc programs provided by panel manufacturers.
Is less conservative than EOL method, allowing more devices on a circuit.
The difference in results from the EOL method can be as much as 30% or more.
Either method is valid and “safe” to use.

17. Fire Alarm & NAC Panels
Per the new U.L.-864, 9TH Edition Standards for fire alarm control panels:
All panels must have a demonstrated 20.4 VDC “panel cut-off ”
That is 85% of the 24 volt battery capacity, i.e. the end of “standby”.
The panel must stop working then to not destroy the batteries.
All fire alarm control panels (and power supplies, which are included) have an internal voltage drop.
The voltage at the NAC output terminals is always less than 20.4 volts at cut-off.
The amount of that drop varies with every panel (from about .5 volts to 2.5 volts).

18. Therefore:
It is the terminal voltage at cut-off that must be used for a meaningful voltage drop calculation.
Note: You won’t typically find this voltage figure on engineering data sheets.
Usually, one has to get it from the panel manufacturers’ engineering department.
Some manufacturer’s calc programs use that terminal voltage (if current).
This aspect needs to be confirmed with the manufacturer and can’t be assumed.
Get it in writing…or at least by from the manufacturer’s rep.
Important: System designers, using their own spreadsheet programs, should supply the values they used (with factory confirmation of validity) to the design reviewer.
It is easy to set up the spreadsheet program to list all values used.

19. The End-of-Line (EOL) Voltage Drop Calculation
To create a basic EOL voltage drop calculation:
Add up current draw for all devices on the circuit using U.L. Max. figures.
Those figures are typically on all CURRENT data sheets for notification devices listed for use in public mode systems (see handout).
Add up total wire length for entire circuit, i.e. run lengths times two (if class B)
Multiply total wire length times the wire resistance value per foot for total circuit wire resistance.
Multiply the total circuit wire resistance times the total current draw for all devices to get the voltage drop.
Subtract the voltage drop from the panel cut-off terminal voltage to get the voltage delivered to the last device on the circuit, which must exceed 16 volts.
This method assumes voltage drop at each device will be the same – it’s not really.
Can have a 20% to 40% margin of error (in extra “headroom”).
Note comparison in sample calculation results for margin of error.

20. NAC Voltage Drop Calculation Example
#12 conductors 1..98▲ per 1000 feet
200’ run 50’ run
BPS1 DA NAC POWER BOOSTER
150’ run
100’ run
EOL
NAC 1-1
(75 mA)
NAC 1-2
(125 mA)
NAC 1-3
(200 mA)
NAC 1-4
(100 mA)
Notes for Example:
Run lengths are shown above.
Wire length = two times the run length.
Current draw shown is VDC (i.e. U.L. Max.)
In this example, panel cut-off terminal voltage assumed to be 19.1 VDC

21. The EOL Voltage Drop Calculation Formula
STEP 1: D (wire run distance) X 2 (two conductors) X R/ft. (wire resistance per ft.)
= Rt (total circuit resistance)
Note: Wire resistance figures used should either be from Chapter 9, Table 8 in the NEC, or, from the wire manufacturer IF the wire part number appears on the plans. Reviewer should have this info confirmed.
STEP 2: Rt X I (total circuit load using U.L. Max.) = Total circuit voltage drop at EOL.
STEP 3: Subtract voltage drop from terminal voltage to confirm voltage at last device, which must exceed 16 volts.
That’s all there is to it!
A sample calc using the example on previous page:
500’ x 2 x ohms (NEC listed value for 12 AWG stranded) = 1.98 ohms
1.98 ohms x .5 amps = .99 volts total voltage drop
19.1 VDC (cut-off terminal voltage) – .99 VDC = last device
I know…12 AWG isn’t a good choice for use with notification devices! 21

22. The Point-to-Point Voltage Drop Calculation (continued)
In the PTP calculation method there is a computation for each wiring segment.
– Uses revised (updated) voltage at each device due to drops for each segment.
Relies on a fixed current draw value (hopefully using U.L. Max values), making it conservative.
In reality, the higher the voltage (closer to the panel), the lower the current draw of that device, making the calc somewhat conservative too.
– Can be very time consuming to do by hand due to the many steps. Thus, most designers need to use a spreadsheet program to employ this method.

23. Regulated or FWR?
Fire alarm system power supplies are typically either “regulated” or “full wave rectified” (FWR).
FWR power outputs are much less “linear” than regulated outputs, and therefore less efficient.
Thus, devices powered by FWR power draw more current than with regulated outputs.
HOWEVER, Power supply type has nothing to do with battery or voltage drop calculations (sigh of relief by plan reviewers since they can ignore that).
THEREFORE, the only reason to use FWR current draw figures is to confirm max. power supply loading on primary power when the power supply is FWR.
Batteries are one of the most pure forms of regulated power supplies Output is very linear and efficient for connected fire alarm devices.
- Battery and voltage drop calculations should only be done with the assumption that system is on secondary (battery) power.
- Once on secondary battery power, all power supplies become regulated.
NOTE: We don’t need to get any more technical than that!

24. Info Needed with Any Voltage Drop Calculation Submittal1.
The NAC terminal voltage for each panel type used in the calculations, supported by manufacturer’s confirmation. 2.
The U.L. Max current draw figures used in calculations, supported by data sheets for each model used with system, which should match the parts list on drawings. 3.
The resistance per foot for each wire gauge (AWG) used in NAC circuits, either using the NEC tables or manufacturer’s figures IF supported by a data sheet and specified by part number(s) on the drawings. 4.
The basis of the math used within the calculation program, i.e. point-to- point, end-of- line, or “something else”, spelling out all math steps used.
Note: “Something else” is probably a baseless figment of someone’s imagination or wishful thinking. There’s a lot of that out there.
Also note: If the calc program came from the manufacturer of the panels being used; and, is current enough to take the panel cut-off voltage into account; then, it is probably valid since their name is on it (i.e. manufacturer’s instructions). The manufacturers typically don’t volunteer to provide the details on the math in programs they supply to their distributors for several reasons. A manufacturers’ (or anyone’s) calc program should be capable of printing out quantities and current draw figures used for all devices in the calculations, which should be included in
any submittals to the local AHJ. 24 15

25. Estimating Wire Lengths for Voltage Drop Calculations
Estimating wire lengths for each circuit is not difficult.
It must be conservative to ensure it will work.
Being short on wire length estimates can result in system failures.
When estimating wire run lengths:
- Allow worst case for power supply locations in fire alarm panel rooms.
Allow worst case for wire run elevation (i.e. run at beam height) and length of vert. drop into devices.
Wire runs are always (code) required to follow building lines.
The wire run length for all NAC circuits should be estimated and provided, regardless of length, both for current review and future reference.
These values, along with calculated resistances, are what the installers should use to compare their required circuit measurements when confirming there are no shorts or opens. Hopefully, all jurisdictions are enforcing that part.
This info can also be useful when doing tenant improvements.

26. Those Non-UL 1971 (Higher Voltage Demand) Devices
Non-UL 1971 NAC devices can only be used in “private mode” fire alarm systems.
How to provide meaningful calculations can be the $64,000 question.
No requirement to operate from 16 VDC to 33 VDC, making voltage drop calculations
“difficult” and sometimes baseless.
Operating voltage can be higher than the power supply cut-off voltage.
Sometimes, pressing the manufacturer to provide the listed operating range is difficult though called for. It’s often not on their data sheets.
Frequently, the only way to allow for voltage drops and the panel cut-off is to “throw in” a 50% to 200% additional battery capacity as a “best guess” allowance.
When non-UL 1971 devices are used, it’s best to call for a functional battery standby test to confirm it will work.

27. Calcs for “Worst Case” Circuits Only?
What is a “worst case” NAC circuit?
Only the one with the longest wire run?
Only the one with the most devices connected?
Answer: You probably won’t know until you run (or see) the calcs.
The “worst case” could be (for instance) the third longest circuit with the third greatest device load connected.
There frequently won’t be a simple “worst case” of having both the longest wire run plus the largest load connected.
So, providing multiple circuit calculations, for all but the obviously smallest combined loads and wire lengths, are justified.
The people who try to cut corners on this are typically the ones who also leave important stuff out that can result in catastrophic system failures.
A Note to Plan Reviewers and Final Inspecting Local AHJ’s:
If you consistently review the integrity of the calculations (i.e. the validity of the values being used); and, confirm that the wiring integrity testing is done in conjunction with those calculation values; you will probably end up with far fewer

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