Test adapters are pluggable devices that allow a test and measurement probe to be inserted into a terminal block both quickly and safely. Using the bridge shaft in the terminal block, the test plug, or adapter, makes reliable contact with the current bar. This allows users to quickly measure voltage or amperage that is carried through the block. The adapter permits safe measurement without coming in contact with a closed circuit. Adapters are available in a variety of styles, including removable or permanent connection depending on the application.