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
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 |
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.