Lock for a test station apparatus

A cathodic test station apparatus for coupling conductor leads extending from a pipe, a casing, an anode, the soil or the like to a device to measure, supply or respond to an electrical current or potential, said apparatus including the combination of a support member, a collar including a side wall to engage said support member for support thereby, said collar including an end wall having an opening to pass test leads through the collar, at least one thread segment on only a peripheral part of the side wall of said collar, terminal block means including terminals supported by said collar to traverse across the opening therein for supporting test leads when extending through the opening, cover means, including an internal support seat engageable with said collar, for enclosing said terminals, said cover means further including a rim portion having at least one circumferential thread bar spaced from said support seat for urging said seat into clamping engagement with said collar when said thread segment and said thread bar are in engagement and are rotated relative to each other whereby said clamping engagement increases by continued rotation of said cover means until further rotation is impossible, said rim portion having at least one discontinuous circumferential recess between terminal ends of said thread bar, said circumferential recess having a peripheral length at least equal to the length of said thread segment for passage of said thread segment into said rim portion, and a generally L-shaped lock carried by said end wall with a radially extending resilient leg overlying the outer surface of the side wall of said collar adjacent the leading end of said thread segment thereon, said cover means and the rim portion thereof enclosing said L-shaped lock when threadedly engaged with a thread segment on said collar and said L-shaped lock lockingly engages a trailing end of said thread bar thereby preventing counterrotation, the resilient leg of said lock projecting from the rim portion of said cover for allowing access thereto so the depressing said resilient leg toward the side wall of said collar moves said resilient leg into an unlocked position whereby said thread bar can counterrotate past said resilient leg.