Type PK-2 test blocks are essentially 4-pole and 6-pole jacks, provided with molded Textolite covers that have internal plug contacts, which make a through connection when the cover is in place. The contacts in the blocks are of the line- pressure type and provide positive contact with minimum contact resistance. For all current circuits, auxiliary contacts are used which automatically short circuit the current transformer when the cover, or plug is removed. 

For mounting on switchboard panels for use in conjunction with proper test equipment to facilitate the testing of ac instruments, meters and relays.