Wiska EN20 Earth Nut Pack of 6. Wiska is one of the leading producers of cabling accessories, known for their reliable and efficient products even in adverse conditions. The Wiska EN20 is a 20mm brass locking earth nut designed to expedite cable gland installation by replacing the earth tag and lock nut, ensuring a high-integrity earth connection. Each nut is equipped with grub screw and washer. The brass earthing nuts feature raised teeth on one side to securely fasten to the box. They can be used with lock rings for conduit connection, providing extra bite during tightening and eliminating the need for couplers and bushes.