Notification Appliance Circuit Voltage Drop Calculator
Estimate segment-by-segment voltage drop and appliance terminal voltage for a supported two-wire DC notification circuit.
Enter circuit and device data
Use manufacturer resistance at expected conductor temperature.
Route segments
End-of-line appliance voltage
About this calculator
Model a radial DC notification circuit as a series of route segments. Enter each segment’s one-way length and the appliance current connected at its end to estimate voltage at each appliance location.
Use matching manufacturer data for appliance current and minimum terminal voltage, and enter conductor resistance for the expected conductor temperature.
Method and assumptions
For each segment, current equals the sum of appliance currents at that segment and every downstream segment. Segment drop is current multiplied by loop resistance; loop resistance uses twice the one-way length and entered one-conductor resistance.
This model assumes a two-wire radial circuit with steady DC load. It does not model branching topology, synchronized transient behavior, power-supply regulation, or multiple circuit paths.
FAQs
What current belongs at each segment?
Enter the appliance current connected at the end of that segment. The calculation adds that value to all downstream appliance currents to determine current in each segment.
Where do I get appliance current and minimum voltage?
Use the notification appliance manufacturer data for the selected operating mode and the power supply documentation. Do not substitute nominal current or voltage values without checking the product data.
Sources
Use the listed compatibility, current draw, and minimum operating voltage from the exact notification appliance and fire alarm power supply manufacturer documentation.