There is a replica of the Electric Chair used at Sing Sing, now called the
Ossining Correctional Facility, at the Ossining, NY visitors center.  An
original construction blueprint for the chair is also in the same exhibit.
 The chair repro was built by inmates in the vocational shops at the
facility with great difficulty, shocking but true.  One of the original
chairs used at Sing Sing is now at the Greenhaven Correctional Center also
in NY.  It is fully wired and ready to go on an hours notice.  Having sat
in the original chair I can say it was not comfortable, then again the
user's never came back to complain.  Another chair exists at the New York
States Correctional Officers  training center "muesum"?  I do not know of
its exact location.

Best of Luck,
Lou Scrima
Exhibit Design Consultant