We first see the Zone system in Art. 505, which provides this alternative system for Class I locations (the combustibles are gases). The Zones are 0, 1, and 2. But if the combustibles are dust or ...
If the power source is a listed Class 2 transformer or listed Class 2 power supply — or it’s in listed equipment marked to identify the Class 2 power source — you’ve got a Class 2 circuit between the ...