Loop Resistance Calculator

Calculate fire alarm SLC and IDC loop resistance to verify end-of-line supervision compliance.

Input Parameters

Results

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Wire Resistance
ohms
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Splice Resistance
ohms
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Total Loop Resistance
ohms
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Status
Note: Loop resistance is critical for proper end-of-line device supervision. Exceeding manufacturer maximum loop resistance causes trouble conditions or communication failures on SLC and IDC circuits. Always verify against panel installation manual.

Reference

Wire Resistance = 2 x Loop Length x R_per_1000ft / 1000 Splice Resistance = Number of Splices x R_per_splice Total Loop R = Wire R + Splice R Typical max SLC loop resistance: 20-50 ohms (varies by panel) Wire R (ohms/1000ft): 18=6.385, 16=4.016, 14=2.525, 12=1.588, 10=0.999