Fire Alarm Riser Wire Sizing Calculator

Calculate fire alarm riser diagram wire sizing for vertical and horizontal circuit runs.

Input Parameters

Results

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Riser Wire Gauge
AWG
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Floor Wire Gauge
AWG
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Total Voltage Drop
V
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Voltage Drop
%
Note: Fire alarm riser wire must be sized for cumulative current draw of all floors. NFPA 72 requires that voltage at end-of-line devices remains within manufacturer specifications. Larger gauge may be needed for high-rise installations.

Reference

Riser Vdrop = 2 x Height x I_total x R_per_ft Floor Vdrop = 2 x Run_length x I_floor x R_per_ft Total Vdrop = Riser Vdrop + Floor Vdrop Vdrop % = Total Vdrop / System Voltage x 100 Wire R (ohms/1000ft): 18=6.385, 16=4.016, 14=2.525, 12=1.588, 10=0.9989, 8=0.6282