Intrinsic safety barriers are used with which type of circuits?

• A. High-power circuits.
• B. Intrinsically safe circuits.
• C. DC circuits only.
• D. AC circuits only.

Answer: (B)

Intrinsic safety barriers are designed to keep the energy in a circuit within levels that cannot ignite a hazardous atmosphere. They sit at the boundary between safe (non-hazardous) and hazardous areas and work with intrinsically safe circuits—the circuits that are engineered to stay below ignition energy even if faults occur. By limiting voltage and current reaching a field device, the barrier ensures that only a tiny amount of energy capable of being non-igniting can appear at the device in the hazardous area. This is why intrinsic safety barriers are used with intrinsically safe circuits: the whole safety approach depends on maintaining those energy limits.

High-power circuits would exceed the safe energy levels intrinsic safety relies on, so they’re not what barriers are designed for. While intrinsic safety barriers can be used with both DC and AC circuits in practice, the essential idea is the circuit type being intrinsically safe, not the current type.