Where must ERZ boundaries be signposted and which direction must they face for a boundary between a NERZ and an ERZ1?

• A. Signposted in each intake airway and machine access leading into the boundary between a NERZ and an ERZ1, facing into the ERZ1.
• B. Signposted in the boundary itself only, facing toward the NERZ.
• C. Signposted on the surface only, facing downward.
• D. Signposted in all roadways, facing toward both zones.

Answer: (A)

The important idea here is that boundaries between ventilation zones need clear signs at the points where people actually move into the new zone, with the sign oriented so that the workers entering the zone can read it before they are inside it.

For a boundary between a NERZ and an ERZ1, you place signs in each intake airway and in machine access ways that lead into that boundary. The signs face into the ERZ1 side, so they are visible to someone moving into ERZ1. This gives immediate, actionable notice of the zone change and any associated ventilation requirements before entry.

Other placements don’t provide the same effective warning: a sign only on the boundary itself doesn’t give advance notice, surface signs wouldn’t catch underground routes, and signs in all roadways facing both zones would be unnecessary and not give the correct directional cue.