If smoke or flames are coming out of a manhole or vault, take the following precautions:
- Establish a safe perimeter, reroute traffic and notify utility personnel.
- Never park over storm drains or manholes or near potential gas-filled structures. Turn off the vehicle engine. An underground explosion can propel a manhole cover high into the air and cause extensive damage.
- If no one is inside, stay out and let the equipment burn. Unless there is a victim in danger or your incident commander instructs you otherwise, let it burn, and do not enter.
- Even a small fire in a vault can create an atmosphere immediately dangerous to life and health. Make sure to test the air for hazards, such as flammable and toxic gases. Assess the potential for gas migration, then isolate and evacuate affected areas, and eliminate spark hazards.
- Do NOT open vaults or remove manhole covers. Doing so may make an already flammable atmosphere become explosive by adding oxygen to it. And manhole covers can be charged with electrical voltage.
If a victim or downed responder is trapped in a manhole or vault and you must assist them, do not enter until the electric utility confirms that all underground equipment is de-energized. When you enter, wear full PPE and SCBA, and follow your department’s safety procedures for confined space entry and rescue.