The electrical connector block comprises an insulating body and a plurality of conductor terminals mounted in it of which at least one is a protective conductor terminal. It is provided with an additional contacting member which passes through the base of the insulating body facing a connector block support and has at least one exterior plug which can directly make contact in a socket in the connector block support. The protective conductor plug can be mounted in the connector block during manufacture of the connector block or also subsequently to making the connector block without having to dismantle it. The structure and positioning of the protective conductor plug or plugs allows an easy automatic connection to the protective conductor by plugging the conector block into the connector block support.