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Control / Instrumentation Cable Sizing

Capacitance-limited maximum cable length for 4-20mA/HART loops, minimum conductor size guidance, and general EMI separation-distance practice for routing instrument cable alongside power/VFD cable.

AAJappsEngineering Calculation Report

Control / Instrumentation Cable Sizing

HART/4-20mA cable capacitance limits; IEEE 518-style EMI guidance

Generated

For preliminary engineering use only — always verify results against project-specific standards and a qualified engineer's review before use in a real design.

Cable & loop

m
pF/m
nF
m

Capacitance check

Total cable capacitance120.0 nF
Within host capacitance limitYes ✓
Max length for this cable/host1333 m

Conductor size

#24 AWG (0.22 mm²) typically adequate for runs up to ~1500 m — confirm against the loop voltage budget.

EMI separation guidance (general practice)

Shielded twisted-pair instrument cable vs. VFD/motor power cable≥150 mm (6 in)
Unshielded instrument cable vs. VFD/motor power cable≥300 mm (12 in)
Low-level signal cable vs. high-voltage power cable (Level 1 vs Level 4 susceptibility)≥300–600 mm (12–24 in), increasing with power cable current/voltage