NFPA 72 worksheet
Fire Alarm Battery and NAC Worksheet
A fire alarm worksheet for NFPA 72 style standby battery capacity, notification appliance circuit load, wire resistance, voltage drop, and end-of-line voltage review.
fire alarm battery NAC worksheet3 workflow phases4 linked tools6 required inputs
Workflow phases
3
Ordered job steps
Linked calculators
4
Tools used by the worksheet
QA gates
3
Review checkpoints
Page role
Use this page for a defined task before moving to the next project record.
- Audience
- Fire alarm designers, Fire alarm technicians, Electrical engineers, Plan reviewers
- Job
- Device current data, standby duration, alarm duration, circuit length, and conductor size are available.
- Evidence
- Battery load basis: Standby current, Alarm current, Standby and alarm duration; Circuit basis: Appliance count, Wire size, One-way circuit length
- Output
- Battery capacity worksheet; NAC load and spare capacity summary; Voltage drop and EOL voltage record
- Next
- Run workflow phases in order, pass QA gates, then open related authority records before project reliance.
Worksheet record summary
Input status, phase records, QA review, and filing notes for the project record.
| Record area | Count | Engineering use |
|---|---|---|
| Inputs | 6 required / 0 conditional | Trace each value to an accepted source before tool use. |
| Workflow phases | 3 | Run phases in order and preserve each record. |
| Linked calculators | 4 | Open linked calculators from the worksheet phase where they belong. |
| QA gates | 3 | Retain review evidence before saving the worksheet record. |
Filing notes
- 16 required inputs and 0 conditional inputs recorded with source basis.
- 23 workflow phases connected to 4 calculator handoffs and 1 reference handoffs.
- 33 QA gates retained before final engineering or AHJ review.
- 44 project records retained for the calculation package.
Worksheet fit check
Confirm the worksheet matches the project record before opening every phase.
| Decision | Use boundary | Record to keep |
|---|---|---|
| Use when | Battery sizing, NAC loading, conductor resistance, and voltage drop need to be reviewed as one fire alarm circuit record. | Device currents, durations, circuit length, wire size, NAC load, and end-of-line voltage. |
| Do not use when | The task is only a quick single-circuit voltage drop or a standalone battery amp-hour estimate. | Use the matching calculator and keep its source device data. |
| Retain record | Keep the worksheet when the circuit data will support submittal review, field troubleshooting, or power supply coordination. | Battery capacity, NAC spare capacity, voltage drop, and listed device data basis. |
Worksheet input matrix
Trace each required value to its source before running linked calculators.
| Group | Field | Source | Required | Used for |
|---|---|---|---|---|
| Battery load basis | Standby current | Panel schedule or device current summary | Required | Battery capacity |
| Battery load basis | Alarm current | Alarm load summary and notification appliance data | Required | Battery capacity and NAC load |
| Battery load basis | Standby and alarm duration | Project criteria and NFPA 72 design basis | Required | Required AH |
| Circuit basis | Appliance count | Notification appliance circuit schedule | Required | NAC load |
| Circuit basis | Wire size | Fire alarm drawings or conductor schedule | Required | Resistance and voltage drop |
| Circuit basis | One-way circuit length | Field route length or drawing takeoff | Required | Round-trip voltage drop |
Worksheet workflow
Run phases in order so the worksheet answers the full job intent, not only one formula.
| Phase | Objective | Actions | Linked tools | Acceptance gate |
|---|---|---|---|---|
| 1. Build load schedule | Collect standby current, alarm current, appliance count, and source voltage before sizing. | List standby loads, List alarm loads, Confirm source voltage and minimum device voltage | Current values come from listed equipment data or a device schedule. | |
| 2. Size standby battery | Calculate required AH with the intended duration and aging margin. | Enter standby current, Enter alarm current, Apply required margin, Review suggested battery size | Battery capacity is rounded to an available battery configuration and flagged for review if oversized. | |
| 3. Check NAC load and voltage | Review circuit loading, spare capacity, conductor resistance, and end-of-line voltage. | Calculate total NAC load, Lookup AWG resistance, Calculate voltage drop, Check end-of-line voltage | NAC spare capacity and end-of-line voltage meet the listed device operating basis. |
Worksheet QA gates
Use these gates before the worksheet result is used for design coordination or review.
| Gate | Check | Evidence |
|---|---|---|
| Device data | Current values are taken from current device listings, not generic assumptions. | Battery load basis input group |
| Circuit path | Length is one-way route length and voltage drop includes round-trip resistance. | Wire resistance and voltage drop outputs |
| Capacity margin | Battery and power supply margins are retained with pass or review state. | Battery and NAC calculator outputs |
Worksheet related tools
Checks that calculators, references, and standards are connected to the worksheet phases where they are used.
| Related item | Kind | Worksheet phase | Listed in worksheet | Back link |
|---|---|---|---|---|
| Fire Alarm Battery Capacity Calculator Fire Alarm Battery Capacity Calculator | calculator | 1. Build load schedule, 2. Size standby battery | Declared | Linked back |
| NAC Circuit Load Calculator NAC Circuit Load Calculator | calculator | 1. Build load schedule, 3. Check NAC load and voltage | Declared | Linked back |
| Fire Alarm NAC Voltage Drop Calculator Fire Alarm NAC Voltage Drop Calculator | calculator | 3. Check NAC load and voltage | Declared | Linked back |
| Wire Resistance Calculator Fire Alarm Wire Resistance Calculator | calculator | 3. Check NAC load and voltage | Declared | Linked back |
| NFPA 72 Fire Alarm Calculators NFPA 72 Fire Alarm Calculators | hub | Worksheet standard context | Declared | Linked back |
| AWG Wire Resistance Table for Fire Alarm Circuits AWG Wire Resistance Table for Fire Alarm Circuits | reference | 1. Build load schedule, 3. Check NAC load and voltage | Declared | Linked back |
Records to keep
1Battery capacity worksheet
2NAC load and spare capacity summary
3Voltage drop and EOL voltage record
4Wire resistance basis
Authority records
Document jurisdiction, AHJ, submittal, inspection, or edition-basis records before final project reliance.
Engineering disclaimer
NFPA in USA provides engineering workpapers, calculation checks, and reference tables for project screening and coordination. Final design decisions, code interpretations, submittals, and acceptance records must be completed by qualified professionals and verified against the adopted code, project criteria, listings, and Authority Having Jurisdiction requirements. This site does not issue signed or sealed engineering documents.FAQ
What is the fire alarm battery and NAC worksheet for?+
It organizes a complete preliminary engineering check across inputs, linked calculators, reference tables, QA gates, and retained deliverables.
Can this worksheet replace a sealed calculation package?+
No. It is a structured screening and coordination worksheet. Final design, code interpretation, and submittal documents must be reviewed by qualified professionals and the AHJ.
Why use a worksheet instead of a single calculator?+
A single calculator answers one formula. A worksheet follows the job workflow, keeps input sources visible, links the required tools, and records the review gates before project use.