An electrical connector block is provided having a housing with a pair of generally parallel sidewalls extending from a base member and separated by a trough open on the side opposite the base member, a groove on each sidewall opposite the trough and spaced from the open side of the trough, a cap member having depending arms adapted to slide along the sides of the parallel sidewalls over the open trough, said arms having inturned flanges engaged in the grooves of the sidewall, at least one screw member threadingly engaged in said cap member and carry a clamp member pivoted on the end thereof between the sidewalls for clamping a wire between the clamp member and base member.