225 ILCS 705/18.06

The operator of every mine where motor generator sets or transformers are installed underground shall designate or cause to be designated on the map provided for in this Act, the location of transformer stations and motor generator stations and said stations shall be of fireproof construction. A sufficient amount of sand or rockdust shall be kept in a suitable place convenient to motor generator stations and transformer stations for the purpose of extinguishing any fire starting from short circuiting or otherwise. In addition thereto two suitable chemical fire extinguishers shall be kept in a convenient place.