Cable Sizing Calculator

Instrument Cable Sizing Calculator

Use this calculator to select the minimum safe instrument cable size as per IEC practices. It checks voltage drop, loop resistance, and intrinsic safety suitability.

Input Data

Loop Type 4–20 mA Analog Solenoid Valve Digital Signal Supply Voltage (VDC) Minimum Device Voltage (VDC) One-way Cable Length (meters) Loop Load Resistance (Ohms) Ambient Temperature (°C) Hazardous Area Safe Area Ex i Intrinsically Safe Design Safety Margin (%) 10 20

Standards Used

• IEC 60228 – Conductor resistance
• IEC 60079 – Hazardous areas
• ISA RP12.6 – Intrinsic safety
• IEEE 525 – Cable sizing fundamentals

Assumes copper conductor. Minimum practical field cable size enforced as 1.5 mm².