RRB ALP Wireman Trade — Solved Practice Question Bank

Q: In a switch-controlled circuit, should the switch be connected in the phase (live) wire or the neutral wire? Sol: The phase (live) wire — this ensures the load is fully de-energized when the switch is off; switching the neutral alone would leave the load still connected to live potential even when "off." Q: Why is crimped jointing widely preferred over simple twisted joints in modern practice? Sol: Crimped joints, made with a proper crimping tool and connector/lug, give a consistent, low-resistance, mechanically strong connection without needing heat, and are faster/more reliable than a bare twisted joint. Q: What is the risk of using an undersized cable for a given load? Sol: The cable overheats under load current beyond its rated capacity, posing a fire hazard and accelerating insulation breakdown.

Q: What is the main safety purpose of earthing an appliance's metal body? Sol: To provide a low-resistance path for fault current, ensuring quick tripping of protective devices and limiting the touch voltage on the metal body to a safe level, preventing electric shock. Q: What does the Lockout-Tagout (LOTO) procedure prevent? Sol: Accidental re-energization of equipment while someone is performing maintenance on it — isolating the power source and tagging it identifies who has locked it out and why. Q: Why should both an MCB and an ELCB/RCCB be used together in an installation, rather than just one? Sol: An MCB protects against overload and short-circuit current, while an ELCB/RCCB specifically protects against earth leakage current (shock hazard) — each protects against a different fault type, so together they provide more complete protection.