During performance of an activity underground described in Table C-2 or when falling sparks or hot metal from work performed in a shaft, raise, or winze could pose a fire hazard —

(a) A multipurpose dry-chemical fire extinguisher shall be at the worksite to supplement the fire extinguishing equipment required by §57.4600; and

(b) At least one of the following actions shall be taken:   (1) Wet down the area before and after the operation, taking precaution against any hazard of electrical shock.   (2) Isolate any combustible material with noncombustible material.   (3) Shield the activity so that hot metal and sparks cannot cause a fire.   (4) Provide a second person to watch for and extinguish any fire. Table C-2 Activity Distance Fire hazard Welding or cutting with an electric arc or open flame Within 35 feet of — More than 1 gallon of combustible liquid, unless in a closed, metal container. Using an open flame to bend or heat materials More than 50 pounds of non-fire-retardant wood. Thawing pipes electrically, except with heat tape More than 10 pounds of combustible plastics. Soldering or thawing with an open flame Within 10 feet of — Materials in a shaft, raise, or winze that could be ignited by hot metal or sparks.   (5) Cover or bulkhead the opening immediately below and adjacent to the activity with noncombustible material to prevent sparks or hot metal from falling down the shaft, raise, or winze. This alternative applies only to activities involving a shaft, raise, or winze.

(c) The affected area shall be inspected during the first hour after the operation is completed. Additional inspections shall be made or other fire prevention measures shall be taken if a fire hazard continues to exist.