US Patent 7178969 Mogul lamp holder

A lamp holder is disclosed lamp holder that will accept and make electrical contact with a lamp having a predetermined base and will accept, but not make electrical contact with lamps having other bases. A cavity (or central well) in the base (or floor) of the lamp socket is provided to accept a lamp configured with an extension extending from the base of the lamp and providing a vertically mounted electrical contact in the cavity that can only be contacted by a lamp contact that is placed at the end of the lamp base extension. A lamp lacking such an extension and a contact on such extension, cannot extend into and engage the contact in the cavity.