I am trying to find the definition of cinder concrete/fill. I have used emt with compression fittings in the slab to avoid some sort of interference with computers. At least thats what microsoft says. We could not use smurf tube,except in the garages and on the roof. I see that EMT cannot be used in cinder concrete 358.12. What is this stuff? I cant find it in any electrical dictionary (dont have ieee dic.) Webster's says volcano rock. Are they refering to cinder pre-cast blocks?