Wiring 29 — Intrinsically Safe 4–20 mA Loop

Intrinsically Safe 4–20 mA Loop

Build an intrinsically safe analog loop across the safe-area / hazardous-area boundary. The galvanic barrier limits the electrical energy that can reach the field transmitter. A loop calibrator on the safe side provides a controlled commissioning signal without entering the hazardous circuit.

Why it is wired this way

Intrinsic safety depends on the complete entity-parameter calculation, approved apparatus, cable capacitance/inductance and installation practice—not on a blue module alone. Barrier earth, segregation and terminal identity are safety-critical.

Commissioning standard

Before energising, prove protective earth and continuity, verify the drawing terminal-by-terminal, then energise through the protective device and measure the expected supply, signal and return values. Never use this training panel as a substitute for the machine manufacturer’s instructions, risk assessment, isolation procedure or applicable electrical standard.