Manhole and Chamber Entry Safety
Confined Spaces › Equipment › Manhole and Chamber Entry Safety
Manhole and Chamber Entry Safety
Manholes and below-ground chambers on construction sites and operational infrastructure must be treated as confined spaces. They may contain toxic gases including hydrogen sulphide and methane, have oxygen-depleted atmospheres, and present drowning risks from water accumulation. Entry requires a confined space entry permit, atmospheric monitoring, a trained top man, and rescue equipment. Many fatalities have occurred in manholes that were assumed to be safe because they had been entered before without problems.
- Treat every manhole and below-ground chamber as a confined space requiring a permit for entry.
- Test the atmosphere using a calibrated multi-gas detector before opening the cover and before entry.
- Obtain a signed confined space entry permit before any person descends into the manhole.
- Ensure a trained top man is stationed at the manhole opening throughout the entire entry duration.
- Position rescue equipment including a tripod and winch at the entry point before anyone enters.
- Provide forced ventilation to maintain safe atmospheric conditions during the work.
- Lower the gas detector into the manhole before entry and test at multiple depths.
- Wear a full body harness connected to the rescue winch for the entire duration of the entry.
- Monitor the atmosphere continuously during the entry and evacuate if any alarm activates.
If a person becomes unresponsive in a manhole, do not enter without breathing apparatus. Use the tripod and winch to extract them. Call 999. Attempting rescue without BA is the most common cause of multiple deaths in manhole incidents.
- Every manhole and below-ground chamber must be treated as a confined space without exception.
- Atmospheric testing must be carried out at multiple depths before anyone descends into the manhole.
- A confined space entry permit must be completed and signed before any person enters.
- The rescue tripod and winch must be assembled and ready at the opening before the first person enters.
- More people die trying to rescue colleagues from manholes than from the original gas exposure.
- Never assume a manhole is safe because it was entered without problems previously — conditions change.
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