Device for locating in buildings the exact position of hidden objects

A device for locating hidden objects such as electrical boxes, in buildings which objects are to be exposed by providing a hole in a covering unit, such as a plate like wall, over the object, said device comprising:

• a first annular magnetic body mounted at the object to be located on one side of said covering unit, said first body having a guide hole formed therein, and having a conically tapered recess formed around said guide hold, said recess having a diameter greater than the diameter of said guide hole;
• a second annular magnetic body which is movable along the other side of said covering unit for sensing the position of said first magnetic body, said second body having a guide hole formed therein, said guide holes being positioned on said bodies so as to be alignable on opposite sides of said covering unit for guiding a drill through said covering unit;
• means for releasably attaching said first magnetic body to said object whereby said first magnetic body can be removed from said object after said object is located and exposed;
• and
• wherein one of said magnetic bodies is a permanent magnet.