These explosion proof grounding terminals, millions of which have already proved their worth in practical applications, are suitable for installations in apparatus, machinery and installation equipment of all types. They are used chiefly in applications requiring a locked screw connection. WECO terminals provide maximum operational reliability and meet the requirements of the corresponding VDE regulations. The upper section of a DF terminal comprises a grounding nut, a flat clamping member which is mounted so that it can rotate and a spiral spring (in case of 4 mm2 terminals a lock washer 3,5 DIN 7980 is used instead of a spring, these upper sections are called DR). The spring with extra-long spring travel is mounted captive on the inside of the upper section between the collar of the clamping member and the grounding nut. The lathe-turned journal above the plate-shaped collar is slightly longer than the block length of the spring so that it absorbs most of the pressure and the spring is thus not subject to fatigue. The fitted spiral spring produces a strong blocking effect (friction locking) and exerts a long-term, reliable pressure on the clamped conductors. The upper section encloses the lower section and thus prevents the legs from bending outwards.