Patent ID: 7644508

Claim:
An installation space determination probe for retrofit recessed lighting fixtures comprising: (a) a handle adapted to be grasped for rotation by a user comprising a top end and bottom end defining a rotation axis, where a first section of a probe rod extends upward from the top end along the rotation axis and bearing along its length indicia of measurements of length and a second section of a probe rod extends perpendicular to the first section from its upper end; (b) an installation radius distance defined from the rotation axis to an end of the second section; (c) an installation space comprising a cylindrical space defined above an underside of a ceiling covering material whose height and diameter equal those of a housing of the retrofit recessed lighting fixture intended for installation therein, whereby the installation radius distance is one half of said installation space diameter; and (d) a normalization plate slidable along the length of the first section adapted to engage a top surface of the normalization plate with said underside of the ceiling covering material whereby the first section is maintained in a position parallel to said underside when a user impresses the first section through an installation hole in the ceiling covering material.