Where angles occur in a line subjecting the supports to increased strain, guard irons must be placed at the outside ends of the crossarms. Guard wires must be placed wherever their presence would prevent fire alarm, telegraph, telephone or other wires from coming into accidental contact with electric light or power wires. The cost of such guard irons and wires shall be borne by the person making the last construction. (Code 1941, Art. 105-18)