Point-to-Point (PTP) Reports - User Guide

Anthony Conte

October 26, 2025 21:05

Overview

The Point-to-Point (PTP) Report feature generates detailed voltage drop calculations for fire alarm circuits, showing electrical characteristics from the power source through each device to the end of the line. These reports are essential for code compliance, demonstrating that all devices receive adequate voltage and current for proper operation.

What Do PTP Reports Calculate?

The PTP report determines:

Voltage at Each Device: Actual voltage available after accounting for wire resistance and distance
Voltage Drop: How much voltage is lost between devices due to wire resistance
Remaining Current: Available current at each point in the circuit
Wire Resistance: Electrical resistance based on wire gauge and distance
Code Compliance: Whether devices meet minimum voltage requirements

Key Concepts

Point-to-Point Analysis

Point-to-Point means the calculation proceeds sequentially from device to device along the circuit:

Starts at the power source (panel or control module)
Calculates voltage drop to the first device
Subtracts that drop from starting voltage
Uses the new voltage as the starting point for the next segment
Continues until reaching the end-of-line device

This provides accurate, real-world voltage values at every device location.

Voltage Drop

Voltage Drop is the reduction in electrical potential caused by:

Wire Resistance: Resistance per unit length (Ω per 1000 feet)
Distance: Physical wire run length between devices
Current Load: Electrical current flowing through the wire

Formula:

Resistance (Ω) = Wire Resistance (Ω/kFt) × 2 × Distance (Ft)
Voltage Drop (V) = Resistance (Ω) × Current (A)

The "×2" factor accounts for both conductors in the cable (positive and negative).

Remaining Current

Remaining Current represents the total load (current draw) from all devices downstream from the current point in the circuit. This value is used in voltage drop calculations to determine how much current is flowing through each wire segment.

NAC/Notification Circuits: Remaining current decreases as you move through the circuit (each horn/strobe reduces the downstream load)
SLC/Initiating Circuits: Remaining current remains nearly constant (detectors draw minimal current)

The remaining current at each device determines the voltage drop in the wire segment leading to that device, as voltage drop is calculated by: Voltage Drop = Resistance × Remaining Current.

Minimum Voltage Requirements

Fire alarm devices must receive adequate voltage to operate correctly:

Typical Minimum Voltage: 16V for most devices (some may require higher)
Nominal Voltage: Typically 20.4V DC at the panel (calculation starting voltage)
Code Requirement: All devices must receive at least their minimum rated voltage

The PTP report highlights devices that fall below minimum voltage requirements.

Report Types

1. Detailed Point-to-Point Report

Shows every device with full electrical characteristics.

When to use:

Engineering design and analysis
Troubleshooting voltage drop issues
Detailed code compliance submittals
Understanding exact voltage at specific devices

Content:

One row per device
Full voltage drop calculations
Distance and resistance values
Configurable columns (50+ available)

2. Summary Point-to-Point Report

Shows circuit-level and card-level totals without individual device details.

When to use:

Quick circuit capacity overview
Card utilization analysis
Management summaries
Identifying circuits approaching limits

Content:

One row per circuit
Current totals (max, used, spare)
Voltage summary (start, end, drop)
Card capacity aggregates

Default Column Structure

The detailed PTP report uses the following default columns (12 total):

Column	Header	Description
1	Device Label	Device address or label (e.g., "SD-1", "HS-2-3")
2	Part No	Manufacturer part number
3	Description	Device description/name
4	Alarm Current (A)	Current drawn during alarm condition
5	Candelas	Light output for visual devices (strobes)
6	Remaining Alarm Current (A)	Remaining load from downstream devices at this point in circuit
7	Distance From Previous	Wire run length to previous device (Ft or M)
8	Resistance From Previous (Ω)	Electrical resistance of wire segment
9	Voltage Drop From Previous	Voltage lost in this wire segment (V)
10	Voltage At Device	Actual voltage available at this device (V)
11	Total Voltage Drop	Cumulative voltage drop from circuit start (V)
12	Voltage Drop Percent	Percentage of starting voltage lost

Additional Available Columns (40+ more)

Users can customize reports by adding/removing columns:

Identification: Symbol, Drawing ID, Device ID, Entity Handle, Block Name, Circuit Device ID

Properties: Manufacturer, Model, Building, Floor, Location, Category, Product Line, CSFM, Approvals

Device Specs: Size, Mounting, Trim, Box, Standby Current, Watts, Decibels, Nominal Voltage, Minimum Voltage, List Price

Calculations: Remaining Standby Current, Remaining Watts

Addressing: Address Quantity, Branch No, Connection Sequence, Address (First/Last), Sub Address (First/Last)

Documentation: PDF Path, Detail Drawing Path, Custom Properties, Entity Properties

Existing Conditions: Is Existing (flag for existing vs. new devices)

User-Configurable Options

Report Settings

Access these settings in Options Editor under Report Settings.

1. Include Child Circuits

Default: Enabled

Includes devices from child circuits connected through passthrough/riser devices.

What it means: If you have a NAC riser feeding control modules on multiple floors, child devices (floor-level strobes/horns) are included in the parent circuit's report
When to disable: If you want to see only devices directly connected to the circuit, excluding distributed loads

Example:

With child circuits enabled:
  Main Panel → NAC Riser
    Control Module Floor 1
      → Strobe 1-1
      → Strobe 1-2
    Control Module Floor 2
      → Strobe 2-1
      → Strobe 2-2

With child circuits disabled:
  Main Panel → NAC Riser
    Control Module Floor 1
    Control Module Floor 2

2. Show Hierarchy Part Number

Default: Disabled

Displays parent device part number before child device labels.

Enabled: Child device labels show as "PARENT_PARTNO → DEVICE_LABEL"
Disabled: Child device labels show with just "→ DEVICE_LABEL" prefix
Purpose: Helps identify which parent/riser each child device connects to

Example:

Disabled: → Strobe 2-1
Enabled:  NAC-4 → Strobe 2-1

3. All Caps

Default: Enabled

Converts all text in report to uppercase.

Enabled: "STROBE, RED, WALL MOUNT"
Disabled: "Strobe, Red, Wall Mount"

4. Use Short Description

Default: Disabled

Uses abbreviated device descriptions to save space.

Example: "Smoke Detector, Photoelectric, 4-Wire" becomes "Smoke Det, Photo, 4W"

5. Set Precision

Default: Enabled

Applies number formatting to maintain consistent decimal places.

Current values: 6 decimal places (0.150000 A)
Voltage values: 2 decimal places (23.45 V)
Length values: 0 decimal places (150 Ft)

6. Include Card Totals

Default: Enabled

Shows card/module capacity utilization in summary section.

Enabled: Displays MAX CARD CURRENT, TOTAL CARD CURRENT, SPARE CARD CURRENT
Disabled: Only shows circuit-level totals

7. Remove Empty Columns

Default: Enabled

Hides columns that contain no data for the current circuit.

Example: If no devices have candela values, the "Candelas" column is removed
Purpose: Reduces report width and clutter

8. Report Columns (Customizable List)

Default: 12 columns (see Default Column Structure above)

Allows adding, removing, and reordering report columns.

50+ available columns to choose from
Drag-and-drop reordering in settings UI
Column width customization for each column
Sort options: Some columns can trigger data sorting

Project Settings

These global settings affect all reports:

9. Wire Overage Percent

Default: 15%

Additional wire length percentage to account for non-straight runs, vertical risers, and obstacles.

Formula: Actual Length = Straight-Line Distance × (1 + Overage%/100)
Example: 100 ft straight-line distance with 15% overage = 115 ft actual wire
Typical values: 10-20% for most installations, 25-30% for complex routing

10. Current Precision

Default: 6 decimal places

Number of decimal places for current values.

11. Voltage Precision

Default: 2 decimal places

Number of decimal places for voltage values.

12. Length Precision

Default: 0 decimal places

Number of decimal places for distance/length values.

Point-to-Point Calculation Method

Step-by-Step Process

The system calculates voltage drop sequentially through each device (9 steps total):

Step 1: Identify Circuit Starting Voltage

The calculation begins at the circuit origin (panel output or control module).

Starting Voltage = Nominal Panel Voltage (typically 20.4V)

For child circuits connected via passthrough devices, the starting voltage may be the actual voltage at the parent device location.

Step 2: Calculate Distance to Next Device

Distance is measured from the previous device to the current device.

Distance = Straight-Line Distance × (1 + Wire Overage Percent / 100)

Example (15% overage):

Straight-Line Distance: 80 ft
Wire Overage: 15%
Actual Distance: 80 × 1.15 = 92 ft

Step 3: Calculate Wire Resistance

Resistance is calculated based on wire gauge, distance, and the round-trip nature of electrical circuits.

Resistance (Ω) = Wire Resistance (Ω/kFt) × 2 × Distance (Ft) / 1000

Example (18 AWG wire, 92 ft run):

Wire Resistance: 6.385 Ω/kFt (18 AWG)
Distance: 92 ft
Resistance: 6.385 × 2 × 92 / 1000 = 1.175 Ω

The "×2" accounts for both conductors (positive and negative wires).

Step 4: Calculate Voltage Drop to Device

Voltage drop is determined by Ohm's Law: V = I × R

Voltage Drop (V) = Resistance (Ω) × Remaining Current (A)

Example:

Resistance: 1.175 Ω
Remaining Current: 2.5 A
Voltage Drop: 1.175 × 2.5 = 2.94 V

Step 5: Calculate Voltage at Device

Subtract the voltage drop from the previous device's voltage.

Voltage At Device = Previous Device Voltage - Voltage Drop From Previous

Example:

Previous Device Voltage: 20.40 V
Voltage Drop: 2.94 V
Voltage At Device: 20.40 - 2.94 = 17.46 V

Step 6: Update Remaining Current

As we pass each device, the remaining downstream load decreases by that device's current draw.

Remaining Current = Previous Remaining Current - Device Current Draw

This represents the total load still downstream from this point. The remaining current is what flows through the wire segment TO this device (used in the voltage drop calculation for this segment).

Example:

Previous Remaining Current: 2.5 A (total load downstream before this device)
Device Current Draw: 0.177 A (horn/strobe)
Remaining Current: 2.5 - 0.177 = 2.323 A (load remaining downstream after this device)

For initiating devices (smoke detectors, pull stations), current draw is negligible (< 0.001 A).

Step 7: Calculate Total Voltage Drop

Track cumulative voltage drop from circuit start.

Total Voltage Drop = Starting Voltage - Voltage At Device

Example:

Starting Voltage: 20.40 V
Voltage At Device: 17.46 V
Total Voltage Drop: 20.40 - 17.46 = 2.94 V

Step 8: Calculate Voltage Drop Percentage

Express total voltage drop as a percentage.

Voltage Drop % = (Total Voltage Drop / Starting Voltage) × 100%

Example:

Total Voltage Drop: 2.94 V
Starting Voltage: 20.40 V
Voltage Drop %: (2.94 / 20.40) × 100% = 14.41%

Step 9: Repeat for Next Device

Use the current device's voltage and remaining current as the starting values for the next device, repeating steps 2-8 until reaching the end-of-line.

Complete Calculation Example

Let's walk through a real-world NAC circuit with 3 horn/strobe devices.

Circuit Specifications

Circuit: L1.NAC-1
Wire Gauge: 18 AWG (6.385 Ω/kFt)
Wire Overage: 15%
Starting Voltage: 20.40 V
Starting Current: 3.0 A (circuit capacity)

Device Properties

Device	Type	Current Draw	Straight Distance
HS-1	Horn/Strobe	0.177 A	50 ft from panel
HS-2	Horn/Strobe	0.177 A	60 ft from HS-1
HS-3	Horn/Strobe	0.177 A	45 ft from HS-2
EOL	End-of-Line	0.000 A	30 ft from HS-3

Calculations

Device 1: HS-1

Remaining Current (at this segment):

Total load from all devices downstream = 3 × 0.177 = 0.531 A

Distance:

Actual Distance = 50 × 1.15 = 57.5 ft

Resistance:

Resistance = 6.385 × 2 × 57.5 / 1000 = 0.734 Ω

Voltage Drop:

Voltage Drop = 0.734 × 0.531 = 0.390 V

Voltage at Device:

Voltage = 20.40 - 0.390 = 20.01 V

Remaining Current (after this device):

Remaining = 0.531 - 0.177 = 0.354 A

Device 2: HS-2

Remaining Current (at this segment):

Load from devices downstream = 2 × 0.177 = 0.354 A

Distance:

Actual Distance = 60 × 1.15 = 69.0 ft

Resistance:

Resistance = 6.385 × 2 × 69.0 / 1000 = 0.881 Ω

Voltage Drop:

Voltage Drop = 0.881 × 0.354 = 0.312 V

Voltage at Device:

Voltage = 20.01 - 0.312 = 19.70 V

Remaining Current (after this device):

Remaining = 0.354 - 0.177 = 0.177 A

Device 3: HS-3

Remaining Current (at this segment):

Load from devices downstream = 1 × 0.177 = 0.177 A

Distance:

Actual Distance = 45 × 1.15 = 51.75 ft

Resistance:

Resistance = 6.385 × 2 × 51.75 / 1000 = 0.661 Ω

Voltage Drop:

Voltage Drop = 0.661 × 0.177 = 0.117 V

Voltage at Device:

Voltage = 19.70 - 0.117 = 19.58 V

Remaining Current (after this device):

Remaining = 0.177 - 0.177 = 0 A

Device 4: EOL (End-of-Line)

Remaining Current (at this segment):

Load from devices downstream = 0 A (no devices after EOL)

Distance:

Actual Distance = 30 × 1.15 = 34.5 ft

Resistance:

Resistance = 6.385 × 2 × 34.5 / 1000 = 0.441 Ω

Voltage Drop:

Voltage Drop = 0.441 × 0 = 0 V

Voltage at Device:

Voltage = 19.58 - 0 = 19.58 V

Total Voltage Drop:

Total Drop = 20.40 - 19.58 = 0.82 V
Drop % = (0.82 / 20.40) × 100% = 4.02%

Final Report Table

PANEL A • L1.NAC-1 POINT-TO-POINT REPORT
Wire: 18 AWG (6.385 Ω/kFt) | Wire Overage: 15%

Device  Part No   Description      Alarm    Remaining  Distance  Resistance  Voltage  Voltage    Total      Voltage
Label                          Current (A)  Current (A)    From      From      Drop From   At      Voltage     Drop
                                              Previous  Previous  Previous   Device    Drop      Percent
                                              (Ft)      (Ω)       (V)        (V)      (V)

HS-1    P2RL     Horn/Strobe       0.177      0.531       58      0.734      0.39     20.01      0.39      1.91%
HS-2    P2RL     Horn/Strobe       0.177      0.354       69      0.881      0.31     19.70      0.70      3.43%
HS-3    P2RL     Horn/Strobe       0.177      0.177       52      0.661      0.12     19.58      0.82      4.02%
EOL     EOL-R    End of Line       0.000      0.000       35      0.441      0.00     19.58      0.82      4.02%

CURRENT SUMMARY                             POWER SUMMARY
Max. Circuit Current:      3.0 A             Starting Calc. Voltage:    20.40 V
Total Circuit Current:     0.531 A           Max. Voltage Drop:         0.82 V
Spare Circuit Current:     2.469 A           End Of Line Voltage:       19.58 V
Spare Circuit Current %:   82.3%             Voltage Drop %:            4.02%

Calculation Methods:
  Resistance = Wire Resistance × 2 × Distance
  Voltage Drop = Resistance × Remaining Current

Note: Remaining Current represents the total load from all devices downstream from that point.

Understanding the Report Sections

Header Section

Shows circuit identification and wire properties:

PANEL A • L1.NAC-1 POINT-TO-POINT REPORT
Wire: 18 AWG (6.385 Ω/kFt) | Wire Overage: 15% | Starting Voltage: 20.40V

Panel/Circuit ID: Identifies the specific circuit
Wire Gauge: AWG designation and resistance per 1000 feet
Wire Overage: Percentage added to straight-line distances

Current Summary (Right Panel)

Shows circuit capacity and utilization:

Metric	Description
Max. Circuit Current	Circuit current limit from database
Total Circuit Current	Sum of all device current draws
Spare Circuit Current	Available unused capacity (Max - Total)
Spare Circuit Current %	Percentage of capacity still available

Color Coding:

Green: Spare > 20% (adequate capacity)
Yellow: Spare 10-20% (approaching limit)
Red: Spare < 10% (near or over capacity)

Power Summary (Right Panel)

Shows voltage characteristics:

Metric	Description
Starting Calc. Voltage	Voltage at circuit origin
Max. Voltage Drop	Total voltage lost from start to end
End Of Line Voltage	Voltage at the last device
Voltage Drop %	Percentage of voltage lost

Color Coding:

Green: EOL voltage ≥ minimum requirement
Red: EOL voltage < minimum requirement (code violation)

Child Circuit Hierarchy

How Child Circuits Work

When circuits use passthrough/riser connections, child circuit devices appear in the parent circuit's PTP report.

Scenario: NAC riser circuit feeding control modules on multiple floors, each with local strobes.

Parent Circuit: L1.NAC-RISER

Control Module Floor 1
Control Module Floor 2
Control Module Floor 3

Child Circuits:

L1F1.NAC-LOCAL (Floor 1 strobes)
L2F1.NAC-LOCAL (Floor 2 strobes)
L3F1.NAC-LOCAL (Floor 3 strobes)

Report Display

L1.NAC-RISER POINT-TO-POINT REPORT

Device Label    Part No     Description         Alarm Current (A)   Voltage At Device
CM-1            NAC-4       Control Module      0.050               23.20
→ HS-1-1        P2RL        Horn/Strobe        0.177               22.80
→ HS-1-2        P2RL        Horn/Strobe        0.177               22.10
CM-2            NAC-4       Control Module      0.050               21.50
→ HS-2-1        P2RL        Horn/Strobe        0.177               21.10
→ HS-2-2        P2RL        Horn/Strobe        0.177               20.40
CM-3            NAC-4       Control Module      0.050               19.80
→ HS-3-1        P2RL        Horn/Strobe        0.177               19.40
→ HS-3-2        P2RL        Horn/Strobe        0.177               18.70

→ Indicates devices from child circuits.

Key Points:

Parent devices (CM-1, CM-2, CM-3) are listed first
Child devices immediately follow with "→" prefix
Voltage calculations account for all devices
Summary totals include both parent and child device currents

Troubleshooting

Issue: End-of-line voltage shows in red (below minimum)

Cause: Voltage drop is too high - devices at the end of the circuit receive insufficient voltage.

Solutions:

Increase wire gauge: Use larger wire (lower AWG number)
- 18 AWG → 16 AWG (reduces resistance ~37%)
- 16 AWG → 14 AWG (reduces resistance ~37%)
Reduce circuit length: Split into two shorter circuits
Reduce current load: Move some devices to another circuit
Increase starting voltage: Use 27.6V power supply (if panel supports)

Example Fix:

Problem: EOL voltage = 16.2V, minimum required = 16.8V
Solution: Change from 18 AWG to 16 AWG wire
Result: EOL voltage = 18.9V ✓ (meets requirement)

Issue: Spare circuit current shows red (negative or very low)

Cause: Total device current exceeds circuit capacity.

Solutions:

Remove devices: Redistribute devices to other circuits
Upgrade circuit card: Use higher-amperage card/module
Add circuit: Install additional circuit for some devices
Check device settings: Verify candela/watt settings aren't higher than needed

Issue: Child circuit devices not appearing in report

Cause 1: "Include Child Circuits" setting disabled

Solution: Enable in Report Settings

Cause 2: Passthrough device doesn't have "Enable Riser Connection Features" enabled

Solution: Enable this setting on the control module or passthrough device in Master Template Editor

Cause 3: Circuit type mismatch

Solution: Ensure parent and child circuits have compatible types (NAC-to-NAC, SLC-to-SLC)

Issue: Voltage calculations seem incorrect

Cause: Wire overage percentage not properly set.

Solution:

Verify wire overage matches your installation conditions
10-15% for simple horizontal runs
20-30% for complex routing with vertical risers
Check that actual field distances match drawing distances

Issue: Report shows no data or "empty" message

Cause 1: Circuit not marked for report generation

Solution: In circuit properties, enable "Generate Circuit Report"

Cause 2: Circuit has no devices

Solution: Add devices to circuit or verify circuit connections

Cause 3: All devices excluded from report

Solution: Check "Exclude From Report" flag on device properties

Issue: Report columns don't match expected layout

Cause: Custom column configuration active.

Solution:

Open Options Editor → Report Settings → Report Columns
Reset to default columns or customize as needed
Regenerate report

Best Practices

1. Verify Wire Gauge and Resistance Values

Before generating reports, confirm wire specifications in your circuit properties:

Wire gauge (AWG)
Wire resistance (Ω per 1000 ft)
Wire type (FPLR, FPLP, etc.)

Incorrect wire resistance dramatically affects calculations.

2. Set Realistic Wire Overage

Use appropriate overage percentages:

10-15%: Simple horizontal runs, open ceilings
15-20%: Standard commercial installations
20-30%: Complex routing, multiple floor penetrations, obstacles

Never use 0% overage - field installations always exceed straight-line distances.

3. Check Minimum Voltage Requirements

Verify device specifications before finalizing designs:

Most devices: 16V to 19V minimum
High-current devices (speakers, high-candela strobes): May require higher minimum
Check manufacturer cut sheets for exact requirements

4. Review Summary Before Detailed Report

Generate summary reports first to identify problem circuits:

Quickly spot circuits with low spare capacity
Identify high voltage drop circuits
Prioritize which circuits need detailed analysis

5. Document Child Circuit Relationships

For riser systems:

Clearly label parent and child circuits
Document which control modules feed which child circuits
Use consistent naming conventions (e.g., L1.NAC-RISER → L1F1.NAC-LOCAL)

6. Save Reports with Project Documentation

Export and archive PTP reports:

Include in design submittals
Provide to contractors for field verification
Keep for AHJ approval and inspections
Update after field changes or modifications

7. Use Custom Columns for Specific Needs

Customize report columns based on use case:

Installation: Add Building, Floor, Location columns
Commissioning: Add Address, Sequence columns
Maintenance: Add PDF Path, Detail Drawing columns

8. Regenerate After Design Changes

Always regenerate PTP reports when you:

Add or remove devices
Change wire gauge
Modify wire routing/distances
Adjust device current settings (candela, watts)
Change panel voltage or circuit capacity

Summary

The Point-to-Point (PTP) Report feature provides comprehensive voltage drop analysis for fire alarm circuits with:

Accurate voltage calculations at every device location
Customizable column selection from 50+ available fields
Hierarchical circuit support for riser and passthrough configurations
Summary and detailed views for different use cases
Color-coded warnings for code compliance issues
Professional Excel exports suitable for submittal documentation

The calculation method follows Ohm's Law and electrical engineering principles, accounting for:

Wire resistance based on gauge and material
Round-trip conductor paths (×2 factor)
Sequential voltage drops through the circuit
Current consumption by devices
Wire overage for realistic field conditions

By understanding the settings and calculation method, you can:

Design code-compliant fire alarm circuits
Troubleshoot voltage drop issues
Verify adequate capacity for all devices
Produce professional documentation for permitting and inspections
Ensure reliable operation of life safety systems

Point-to-point reports are essential for fire alarm system design, demonstrating compliance with NFPA 72 and local code requirements for voltage and current delivery to all devices.

FireCAD is the industry-leading AutoCAD add-in for fire alarm system design — from circuit layout to wire routing to code-compliant reports.
Learn more and get started at getfirecad.com →

Inspect Point Integration — Fire alarm system device lists and bill of materials can be pushed directly from FireCAD into Inspect Point, eliminating manual data entry and ensuring every device is ready for inspection scheduling and ongoing asset management.
Learn more here →