Water Supply No. 5 Questions taken from Jones & Bartlett Fundamentals of Fire Fighter Skills (3rd Edition) Progress Indicator: Question 3 of 20 3.  When 1 percent or more methane is present in a working place or return air course, except for intrinsically safe atmospheric monitoring system (AMS), electrically powered equipment in the affected area shall be deenergized, other mechanized equipment shall be shut off. Choices: True False