A method for manufacturing conductive plates, applicable for covering floors or walls, a conductive plate and an injecting machine is provided. The method comprises a) carrying out a polymer concrete mixture or mortar, b) introducing said mortar in a hollow mold with a shape of one of said plates to be obtained when said mortar solidifies, c) making at least one through hole through said mortar deposited in said mold, and d) injecting an electrically conductive ink in said hole, which is at least one in number. A second aspect of the invention relates to a conductive plate manufactured in accordance with the method. A third aspect of the invention relates to an ink injecting machine which can be used to carry out part of the method proposed by the first aspect of the invention.