What do miners wear on their feet?

When performing a voltage drop test on a 12v blower motor circuitthe reading is 2.7 volts across the fan switch when closed. What is the maximum voltage available at the fan? What is the importance of the erth wire in electricity? What is a wildcard for more than one character? What strength concrete is 6 bag mix? Harmful effects of technology? What is meant by pitch measurement in lathe? How many 80lb bags of concrete are in a yard? What metal is a safety pin made from? How much weight can a LEGO bridge hold? When moving a toilet 8 feet how much of an angle does the soil pipe need to be to take the waste away without building up and blocking? Why necessity is the mother of all invention? What could people do to reduce the chances of a mudslide happening on a hill? Why ac is used in domestic and industrial purposes? Who administers Wash DC? You invented the first steam train and was the engineer of the first public railway? What is a type of metal block for securing a railway rail to sleeper? Is Thermocouples active or passive? Is human cloning possible from placenta cells? What is the difference between N50 and S50 concrete grade? How software testing differ from program testing?