Abstract: A terminal block connecting apparatus includes first and second support members displaceable from a disengaged condition toward an engaged condition in which corresponding main terminal blocks are brought into electrical engagement, characterized by the provision of first and second test terminal blocks connected with the support members for electrical engagement when the first and second support members are in an intermediate condition between the disengaged and engaged conditions. One of the test terminal blocks is supported by a carrier member for movement relative to the associated support member, whereby the test terminal blocks will remain in electrical engagement during displacement of the support members between the test and connected conditions. A friction retaining arrangement serves to resist displacement of the carrier member relative to its associated support member.