WTA5-1Test Adaptor A test adaptor for the standard terminals up to 10 mm. The adaptor provides a means of testing circuits even when connection units are in use.,To wire the adaptor, the spring loaded test probe must be pulled out from the front. A test lead of 0.75 mm² may then be passed through the adaptor moulding and crimped to the probe. WTA5-1 fits WDU 2.5 to 10