75.6 If a conductive surface other than metal is used for the enclosure or part of the enclosure, the
leakage current shall be measured using metal foil with an area of 3.9 by 7.8 inches (100 by 200 mm) in
contact with the surface. Where the surface is less than 3.9 by 7.8 inches, the metal foil shall be the same
size as the surface. The metal foil shall not remain in place long enough to affect the temperature of the
unit.